ML16314A994

Resumes

ML16314A994
Person / Time
Site:	Diablo Canyon
Issue date:	11/09/2016
From:	Pacific Gas & Electric Co
To:	Office of Nuclear Reactor Regulation
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Download: ML16314A994 (202)

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'TTACHMENTS A.'Resume-RichardB.Hubbard.B.C.D.E'.Biography

-EliSilver.Biography

-ClarenceA.Hall,~Jr.Resume-StephanAlanGraham.Curriculum Vitae-WilliamR.Dickinson.

G.H.K."TheSanGregorio-Hosgri FaultZone:AnOverview,"

-'liSilver."Evidence for115Kilometers ofRightSlipontheSan'Gregorio-HosgriFaultTrend,"S.A.GrahamandW.R.Dickinson.

"SanSimeon-Hosgri FaultSystem,CoastalCalifornia:

EconomicandEnvironmental implications,"

C.A.Hall,.Jr."OriginandDevelopment oftheLompoc-S'anta MariaPull-Apart BasinanditsRelationtothe'SanSimeon-Hosgri Strike-Slip Fault,WesternCalifornia,"

C.A.Hall,Jr."MarineGeologyandTectonicHistoryoftheCentralCalifornia Continental Margin,"E.A.Silver,D.S.McCulloch, andJ.R.Curry."Application ofLinearStatistical ModelsofEarthquake Magnitude VersusFaultLengthinEstimating MaximumExpectable Earthquakes,"

RobertK.Mark.L.USGSOpenFileReport77-614,"Regression AnalysisofEarthquake Magnitude andSurfaceFaultLengthUsingthe1970DataofBonillaandBuchanan,"

R.K.MarkandM.G.Bonilla.M.N.O.Biography

-JamesN.Brune.Curriculum Vitae-J.EnriqueLuco,Curriculum Vitae-MihailoD.Trifunac.

P.R."Reviewofthe'SeismicEvaluation forPostulated 7.5MHosgriEarthquake, Units1and2,DiabloCanyonSite,'"J.EnriqueLuco."Comments onSeismicDesignLevelsforDiabloCanyonSiteinCalifornia,"

M.D.Trifunac.

USGSOpenFileReport78-509,"Estimation ofGroundMotionParameters,"

D.M.Boore,A.A.Oliver,R.A.Page,andW.B.Joyner.

IgJ.T dqql~hq-~~ATTACHEZARichardB.Hubbard366California AvenueSuite7PaloAlto,CA94306(415)329-0474EXPERIENCE 9/76-PresentPartner-MHBTechnical Associates, PaloAlto,California.'ounder anmanagingpartnerotecnicaconsutingirm.Specialists, in:independent energyassessments forgovernment

agencies, particulary technical andeconomicevaluation ofnuclearpowerfacilities.

Con-sultantinthis.capacitytoIllinoisAttorneyGeneral;SuffolkCounty,NewYork;Schweinfurt, Germany;GovernorofColorado; andSwedishEnergyCommission.

Alsoprovidedstudiesandtestimony forvariouspublicinterestgroupsincluding CenterforLawInThePublicInterest, LosAngeles;PublicLawUtilityGroup,BatonRouge,Louisiana; andUnionofConcerned Scientists, Cambridge,"Massachusetts.

Providedtestimony toU.S.Senate/House JointCommittee onAtomicEnergy,U.S.HouseCommittee onInteriorandInsularAffairs,California

Assembly, LandUse,andEnergyCommittee, AdvisoryCommittee onReactorSafe-guards,andAtomicSafetyandLicensing Board.Performed comprehensive riskanalysisoftheaccidentprobabilities andconsequences attheBarseback NuclearPlantfortheSwedishEnergyCommission andedited,aswellascontributed to,theUnionofConcerned Scientist's technical reviewoftheNRC'sReactorSafetyStudy(WASH-1400).

2/76-9/76Consultant, Pro'ectSurvival, PaloAlto,California.

Volunteer workonNucearSareguarsInitiative campaigns xnCaiornia,Oregon,Washington, Arizona,andColorado.

Numerouspresentations-onnuclearpowerandalternative energyoptionstocivic,government, andcollegegroups.Alsoresourcepersonforpublicservicepresentations onradioandtelevision.

5/75-1/76%fanger-QualitAssurance SectionNuclearEnergyControlandnstrumentation Deoartment, GeneraEectrz.cComoanv,SanJose,axorna.a.eporttoteDepartment eneraManager.Deveopand~pqh'yyd,yd,hd,dq'ph'h thatproductsproducedbytheDepartment meetqualityrequirements asdefinedinNRCregulation 10CFR50,AppendixB,ASMEBoilerandPressureVesselCode,customercontracts, andGECorporate policiesandprocedures.

Productareasincluderadiation sensors,reactor ttvesselinternals, fuelhandlingandservicing tools,nuclearplantcontxolandprotection instrumentation systems,andnuclearsteamsupplyandBalanceofPlantcontxolroompanels.Responsibile forapproximately 45exemptpersonnel, 22non-exempt pexsonnel, and129hourlypersonnel withanexpensebudgetofnearly4milliondollarsandandequipment investment budgetofapproxi-mately1.2milliondollars.11/71-5/75/Manaer-ualitAssurance Subsection, Manufacturing SectionoftomicowerauzomentDeaxtment,eneraectrz.cComDan,'anJose,Caizoxnia.ReporttotheManagerorManuacturing.

Sameunctzonaanproduct-responsiblities asinEngagement

><1,exceptataloweroxganizational

=reportlevel.Developed aqualitysystemwhichreceivedNRCcertification in1975.Thesystemwasalsosuc-cessfully surveyedforASME"N"and"NPT"symbolauthorization in1972and1975,plusASME"U"and".S"symbolauthorizations in1975.Responsible forfrom23to39exemptpersonnel, 7to14non-exempt personnel, and53to97hourlypersonnel.

,3/70-11/71Manaer-Aplication EnineerinSubsection, NuclearInstrumentation eartment,enexar.ectrxcComoan,SanJose,Caiornia.Respon-seeortepostoraertecnnxcaznteracewxtarcdetectengineers andpowerplantownerstodefineandscheduletheinstrumentation andcontrolsystemsfortheNuclearSteamSupplyandBalance.ofPlantportionofnuclearpowergenerating stations.

Responsibilities includedpreparation oftheplantinstrument listwithapproximate

location, reviewofinterface drawingstodefinefunctional designrequirements, andreleaseoffunctional requirements fordetailedequipment designs.Personnel supervised included17engineers and5non-exempt personnel.

12/69-3/70Chairman-EuivmentRoomTaskForce,NuclearInstrumentation Depart-ment,GeneraEectrx,cComan,banose,axorna.a.esponsz.eoraspeciatasforcereporting totneDepartment GeneralManagertodefinemethodstoimprovethequalityandreducetheinstallation timeandcost"ofnuclearpowerplantcontrolrooms.Studyresultedintheconception ofafactory-fabricated contxolroomconsisting ofsignalconditioning andoperatoxcontrolpanelsmountedonmodularfloorsectionswhicharecompletely assembled inthefactoryandthoroughly testedforproperoperation ofinteracting devices.Personnel supervised include10exemptpersonne'l.

I'2/65-12/69Manaer-ProosalEnineerinSubsection, NuclearInstrumentation eaxtment,GeneraEectrxcComoany,SanJose,Cax.ornza.Respon-seeorteappicationoinstxumentatxon systemsornuclearpowerreactorsduringtheproposalandpxe-order"period.,

Respon-siblefortechnical reviewofbidspecifications, preparation of technical bidclarifications andexceptions, definition ofmateriallistforcostestimating, andthe"assold"reviewofcontxacts priortoturnovertoApplication Engineering.

Personnel supervised variedfrom2to9engineers.

8/64-12/65SalesEnineer,NuclearElectronics BusinessSectionofAtomicoweruivmentOeoartment, eneraEectrx.coman,anaose,Caiornia.Responsieforteireview,contractnegotiation, yd~C*1powerplants,testreactors, andradiation hotcells.Alsorespon-sibleforindustrial salesofradiation sensingsystemsformeasure-mentofchemicalproperties, level,anddensity.10/61-8/64AlicationEnineer,LowVoltaeSwitchearDepartment, GeneralEectricCpm@an,Piaexa,Pennsvania.Responsieortheapp>cationanddesignoadvanceiodeansiliconcontrolled rectifier constantvoltageDCpowersystemsandvariablevoltagedcpowersystemsforindustrial applications.

Designed, followedmanufacturing and"personallly testedinadvancedSCRpowersupplyforproductintroduction attheIronandSteelShow.ProjectEngineerforadcpowersystemforanaluminumpotlinesoldtoAnacondabeginning atthe161XVswitchyard andencompassing alltheequipment to.,convert thepowerto700voltsdcat160,000amperes.9/60-10/61GERotational TzaininP~totamFour3-monthassignments ontheGERotational TrainingProgramforcollegetechnical graduates asfollows:a.Installation andServiceEn.-Detroit,Michigan.

Installation anstartuptestingotteworsargestautomated hotstripsteelmill.b.Tester-IndustrControl-Roanoke,Virinia.Factory,testingocontropanesorcontroostee,paper,'ulp, andutilitymillsandpowerplants.c.Enineer-LihtMilitaElectronics

-JohnsonCit,NewYork.eszgnogrounsupportequipment ortestingteautopx,otsontheF-105.d.'alesEn~ineer-Morrison, Illinois.

Saleofappliance controlsincuxngrangetimersanrezrxgerator coldcontrols.

A3 EDUCATION BachelorofScienceElectrical Engineering, University ofArizona,1960.MasterofBusinessAdministration, University ofSantaClara,1969.PROFESSTONAL AFFILIATION Registered QualityEngineer, LicenseNo.QU805,StateofCalifornia.

MemberofSubcommittee 8oftheNuclear-PowerEngineering Committee oftheIEEEPowerEngineering Societyresponsible forthepreparation andxevisionofthefollowing 4nationalQ.A.Standards:

a~IEEE498(ANSI.N45.2.16),Supplementary Requirements fortheCalibration andControlofMeasuring andTestEquipment usedintheconstruction andmaintenance ofNuclearPowerGenerating Stations.

b.IEEE336(ANSIN45.2.4),

Installation, Inspection, andTestingRequirements forInstrumentation andElectricEquipment duringtheconstruction ofNuclearPowerGenerating Stations.

c.IEEEP467(ANSIN45.2.14),

QualityAssurance ProgramRequire-mentsfortheDesignandManufacture ofClassIEInstrumen-tationandElectricEquipment forNuclearPowerGenerating Stations.

d.IEEEDraft,Requirements fortheProcurement andStorageofClassIEEquipment Replacement Parts.PERSONALDATABirthDate:7/08/37Married;threechildrenHealth:Excellent "PUBLICATIONS ANDTESTIMONY 1.SwedishReactorSafeStud:Barseback RiskAssessment, 1KBTecnicalAssociates, January17PuishebySweshDepart-mentofIndustryasDocumentDSI1978:1).2.TheRisksofNuclearPowerReactors:

AReviewoftheNRCReactorSaetStuvMASH-w,Kena,eta,eateyR.B.Hubardan.C.ManoroxUnionofConcerned Scientists, August1977.A

~a~~3.Testimony ofR.B.HubbardtoAdvisoryCommittee onReactorgafeguards, August.12, 1977,Washington, DC,entitled, RiskUncertaint DuetoDeficiencies inDiabloCanonQualitssuranceProramanFar.uretomementCurrentNRCPractices.Testimony R.B.HubbardtoUnitedStatesHouseofRepresentatives, Subcommittee onEnergyandtheEnvironment, June30,1977,Washington, DC,entitled, Effectiveness ofNRCReulationsModifications toDiabloCanonNucearUnx.ts.5.Testimony ofK.B.HubbardandG.C.Minor,JudicialHearingsRegarding Grafenrheinfeld NuclearPlant,March16617,1977,Wurzburg, Germany.6.Testimony ofR.B.HubbardandG.C.MinorbeforeCalifornia StateSenateCommittee onPublicUtilities, Transit,andEnergy,Sacramento, California, March23,1976.~7.Testimony ofR.B.Hubbard,D.G.Bridenbaugh, andG.C.MinortotheCalifornia StateAssemblyCommittee onResources, LandUse,andEnergy,Sacramento, California, March8,1976.8.Testimony ofR.B.Hubbard,D.G.Bridenbaugh, andG.C.Minor.beforetheUnitedStatesCongress, JointCommittee onAtomicEnergy,February18;1976,Washington, DC.(Published byUnionofConcerned Scientists, Cambridge, Massachusetts.)

Excerptsfromtestimony published inuoteWithoutComment,Chemtech, May,1976.9.ualitvAssurance:

ProvidinIt,ProvinIt,R.B.Hubbard,Power,Hay,19710.In-CoreSstemProvidesContinuous FluxMapofReactorCores,R.B.HubardanC.E.Foreman,Power,iVovemer,17.A5.

I~0~'IIIc AUG1B$78ATTACHMENT BBiographical Data,EliSilverAssociate Professor, EarthSciencesUniversity ofCalifornia, SantaCruzBorn-June3,1942B.A.-Geology,University ofCalifornia,

Berkeley, 1964Ph.D.-Oceanography, ScrippsInstitution ofOceanography, 1969Post-Graduate ResearchOceanographer, ScrippsInstitution of'Oceanography, 1969-1970 Geologist, U.S.Geological Survey,1970-1974 Assistant Professor, EarthSciences, University ofCalifornia, SantaCruz,1974-75Associate Professor, EarthSciences, University ofCalifornia, SantaCruz,1975-present Chiefscientist and/orcruiseleaderonnumerouscruisesofScrippsInstitution ofOceanography andtheU.S.Geological SurveyFellow:Geological SocietyofAmericaMember:AmericanGeophysical Union,SocietyofExploration Geophysicists, Seismological SocietyofAmerica,AAASSelectedPublications Moore,G.W.,andSilver,E.A.,1968,Geologyoft:heKlamathRiverDelta,California:

U.S.Geol.SurveyProf.Paper600-C,p.C144-C148.

Moore,G.N.,andSilver,E.A.,1968,Golddistribution ontheseafloorofftheKlamathMountains, California:

U.S.Geol.SurveyCirc.605,9p.Silver,E.A.,1969,LateCenozoicunderthrusting ofthecontinental marginofnorthernmost California:

'Science,-

v.166,p.1265-1266.

Silver,E.A.,1971,Transitional tectonics andLateCenozoicstructure ofthecontinental marginoffnorthernmost California:

Geol.Soc.AmericaBull.,v.82,no.1,p.1-22.

Silver,E.A.,1971,Tectonics oftheMendocino TripleJunction:

Geol.Soc.AmericaBull.,v.82,p.2965-2978.Silver,E.A.,Curray,J.R.,andCooper,A.K.,1971,Tectonicdevelopment ofthecontinental marginoffcentralCalif.:Geological'Society ofSacramento, AnnualFieldTripGuidebook, p.1-10.Silver,E.A.,1971,Smallplatetectonics ofthenorth-easternPacific:Geol.Soc.AmericaBull.,v.82,p.3491-3496.

Silver,E.A.,andothers,1972,USGS-IDOE Leg4,Venezuelan.

borderland:

Geotimes,v.17,p.19-21.Silver,E.A.,1972,Subduction zones:Noterelevanttopresent-day problemsofwastedisposal:

Letter,Nature,v.239,p.330-331.Silver,E.A.,1972,Pleistocene tectonicaccretion ofthecontinental slopeoffNashington:

Mar.Geol.,v13Ip239249Jackson,E.D.,Silver,E.A.,andDalrymple, G.B.,1972,Hawaiian-Emporer chainanditsrelationtoCenozoicCircumpacific tectonics:

Geol.Soc.AmericaBull.,v.83,p.601-618.Dalrymple, G~B.,Silver,E.A.,andJackson,E.D.,1973,OriginoftheHawaiianIslands:AmericanScientist, v61Ino.3,p.294-308~Silver,E.A.,vonHeune,R.,Crouch,J.K.,1974,Tectonicsignificance oftheKodiak-Bowie

seamount, chain,Northeastern Pacific:Geology,v.2,p.147-150.Silver,E.A.,1974,Geometrical principles ofplatetec-tonics:inSanJoaquinGeological, Soc.ShortCourse,Geological Interpretations fromglobaltectonics withapplications forCalif.geologyandpetroleum exploration, N.R.Dickinson, ed.,p.1-1to1-3.Silver,E.A.,1974,Basindevelopment alongtranslational continental margins:inSanJoaquinGeological Soc.ShortCourse,Geological interpretations fromglobaltectonics withapplications forCalif.geologyandpetroleum exploration, N.R.Dickinson, ed.,p.6-1to6-5.B-2 Silver,E.A.,1974,Evolution oftheSanAndreasfaultsystem:inSanJoaquinGeological Soc.ShortCourse,Geological interpretations fromglobaltectonics withapplications forCalif.geologyandpetroleum exploration, W.R.Dickinson, ed.,p.12-1to12-5.Silver,E.A,1974,Detailednear-bottom geophysical profileacrossthecontinental slopeoffnorthernCalifornia:

U.S.Geol.SurveyJour.ofResearch, v.2,p.563-567.Silver,E.A.,Case,J.E.,andMacGillavry, H.J.,1975,Geophysical studyoftheVenezuelan borderland:

Geol.Soc.AmericaBull.,v.86,p.213-226.Silver,E.A.,1975,Collision eventsinorogenesis (abs):13thPacificScienceCongress, Vancouver, Canada.Silver,E.A.,1975,Collision eventsinorogenesis:

EOS,v.56,p.1066.Silver,E.A.andMoore,J.C.,1976,Ageophysical studyoftheMoluccaSeacollision zone,Indonesia (abstract):

EOS,Trans.AGU,v.57,p.1003.Silver,E.A.',1977.TheSulaspurenigma(abstract):

Geol.Soc.Amer.Abs.withPrograms, v.9,p.1175-1176.

Silver,E.A.,1977,AretheSanGregorioandHosgrifaultzonesasinglefaul'tsystem'P(Abstract):

Geol.Soc.Amer.Abs.withprograms, v.9,p.500.Silver,-E.

A.,1978,Geophysical studiesandtectonicdevelop-mentofthecontinental marginoffthewesternUnitedStates,34'o48N:inGeol.Soc.AmericaMemoir,Smith,R.B.andEaton,G.P.,eds.,(inpress).Silver,E.A.andMoore,J.C.,1978,TheMoluccaSeacollision zone,Indonesia:

Jour.Geophys.Res.,v.83.Blake,M.C.,Campbell, R.H.,Dibblee,T.H.,Howell,D.G.,Nilsen,T.H.,Normark,N.R.,Vedder,J.G.,andSilver,E.A.,1978,Neogenebasinformation andhydro-carbonaccumulation inrelationtotheplatetectonicevolution oftheSanAndreasfaultsystem,California-Amer.Assoc.Petroleum Geol.Bull.,March1978.Silver,E.A.,1978,TheSanGregorio-Hosgri faultzone:Anoverview:

Calif.Div.MinesandGeol.SpecialPub.137.Silver,E.A.,McCulloch, D.S.,andCurray,J.R.,1978,MarinegeologyandtectonichistoryofthecentralCalifornia continental margin:Submitted toAAPG.Bull.

0~'4~"Y,+E%

ATTACHMENT CBZOGRAPBY CLARENCEA.EKLJR.SocialSecurityNumber:569-34-9229 Address:2427S.ArmacostAvenue820LosAngeles,CaZifoznia90025Home2'elephone:

(223)473-3061Bvainess2'eZephone:(223)825-2020DateofBirth:Born:,xi~Le:Eaum~tzm:January5,1930-CitizenoftheUnitedStatesLosAngeZes,CaHfornia Propessoz'fGeologpB.S.,StanfordUniversity, 2952lAS.,Sta.fordUniversity, 2953Pn.D.,S~-"ordUniversity, 2956Pa"tciployment:

RomdValleyPmgstenNine,Bishop,CaHfornia, Geologist, 2952U.S.C~ological Suey(Orgon),Geologist, 1953UnivesityofOregon,1'nstrvtorinGeology,2954-55Z~ZeOil~nRefiningCcnvany,Geologist, 2955StanfordUniversity, lnst~mtor inGeoZogp,2956Suv..er~.,pKoyment, V.S.Geological Survey,Geologist, 2972-78Vniversi='w ofCalifornia, LosAngeles,Assistant Pz'ofessoz toProfessor, 2966toPresent;Chairman, Depa~~.ent ofGeology,9-2-74to22-31-76, ActingChairman, Department ofGeophysics andSpacePhysics8-2-76to12-31-76,

Chairman, Depaztment ofEazthandSpaceSciences1-2-77to8-32-78Scholarly Societies:

ZeZZ~GeologicaZ SocietyofAmericaPaleontological SocietyofAmerica-EditorJournalofPaZeontology, 1971-72NalacoZogicaZ SocietyofCaZifozniaZonorsandAwards:Zulbright ResearchScholaz;2taly,2963-64and2970-72invitedLectvwer, PoHshAcademyofScience,2964 C.A.Halls~~~sogi.,~,s2~3e6.7e8.9.195819581959-1959195919591960I'Geologyandpaleontology ofthePleasanton area,AlamedaandcontraCostaCounties, Calif.:Univ.Calif.Pub-Geol.Sci.,v.Q4,no.1,p.1-90,pls.l-l2,2.figs;5maps.Gastropod GenusCeratostoma Geol.Soc.Asser.Bull.,69,.12,I.RR~.S7.(ABII'IIICI'I TheGastopod,Genus'Ceratostoma:

Jour.Paleontolo~,

v.33,no.3,p.428-430,3pls.1959.PigeonpointFormation ofLateCretaceous age,SanElateoCo.Caliz.:Amer.Assoc.Patrol.Geologists Bull.,v.5,no.12,p.2855-2859, 1959.EDisplaced IO.oceneVG3.luscan Provinces alongthe'anAndreasault.PacificPetroleum Geologist Newsletter, Amer.Assoc.Petro3..Geol.,v.13,no.-3,p.4.(ABSTRACT)

Displaced 1ioceneMolluscan Provinces alongtheSanAndreasF"ult,Calif.,Geological SocietyofAmericar--s+(+.srtnsgt,ssss.>nssssssym.x.,v.jO,no.12,pt.,p.Displaceh

'.!iocene Molluscan Provinces AlongtheSan9deasFault,,Calif.:Univ.Cali.Pub.Geol.Soc.~v.3LI,no;6,p.-281-308.CeratosiG.aHerrmannsen, 1%6(ClassGastropoda);

propose"'dition totheOfficiallistofGenericHams.A.Fi.(S)1088:Bull,.Zoo3..Homencl.,

v.18,pt.5,p.336,1961.GeologcYapofCalifornia, SanFrancisco Sheet,Calif.Div.ofI4ines,1961(Contributor).

3.0.196212.1962196411.1962Displaced MioceneYiolluscan Provinces alongtheSanAndreasFaultinGuidebook, Geologyof'arrizo plainsandSanAndreasFault,1962:pac.Sec.Amer.Assoc.Petro3..Geol.,p.20,1962.-'IDisplaced Viocenemolluscan provinces alongtheSanAndreasFault,Calif'.:Amer.Assoc.Petro3..Geol.,v.06,no.10,p.1952-3.960, 1962.Evolution oftheechinoidgenusAstrodapsis:

Univ.Calif.Pub.Geol.Sci.,v.40,no.2,p.$7-180,1962.AreaArc"lepton;ramnica, anewlateTertiary'e ecypoErom.zeSanLuisObi"poPegion,Calif'.:Jour.paleo.,v.3U,no.3.,p.87-88,3.96>i.C-2

'5.ag.I'yusca~,g~0gcI6<~~cg+51I23>pe3-4'lag5'n'as4x~jescaggQ3sv'Chas~e~yaSo~e~~9y964.gQXQAConsxt~ol~gyn.o~ene~><>>1<pe(XS>~~gn~t'64~go<a~.Zo+~g64g~gh~.3~~ana>~g~,d.at'e$46~.es~gute+.~annGeney3-9o'apto~aSg>s<y96-MeT~.Qfas'ej.ttos.fr~a>t,.3>>sggo6e~~~CtheOf2>>~.enusneue@SICy6.~togoyips.enc~'hknopefeTgQGof~'"Sc~.>~gG-'g~on~~u~+g.Geo'oi<eT,ox+s,Cafoss>ftheCoasy,opu>-.gch>no0~~sgo~an~es~a+ye'gageO~ho'gn+ha~)ongSo(~qgQQns5Sgss~-.b>ngg3->",'e's~ocengcI$6~oceg>9egaV>~you>~(>>~paanegea-haeoon~he-23-peShepdacha,.

fzo>Z2Bo:x9~othe0>o~fgh.eGof.Soc-20-"-..-at,>onGo>-Sec~an<~ggz~a><anzojccZeo3-.fomang'gegesoSQ82eeCga>9~of.~of.tuSethemp,~~51a9oquadeT~t,o4~~St~aC5qo~g~yea+y967~OCM>GeohhC~Y~og5-9622-5.a.<x>>th.0>isQ63>.owng6't<guhsgee~'ot~cga$>.eSanSoc~yQ,e~',~.sghGeolQe>~geboooCo'g..2'Pa~Gu0~~so.Sect>.~yesops~'-9Qu>.gyeyan.jgj.ncgC+4~Co~~'usfo'e>S.~ct,use(ir>th-0>>sgpuca'yg6'722'9',Sag,rfense.Guthe.a.T)eCa-~fGoyo~.fga>tozy.shoct~onog>3-9Co-Geo>.t,h~Qe"25-Copseofag<<'ona~ont,>on>>Q.3.t,g3~0Qo~pe<an,SuQuQyQaCSec0'026~.tih<a~s>~yo6<o.2>n 27-197028..197329.19733O-1973-~~~e1~TheObis~Formation andasociat~volcanic rockin.theGentle.California CoastRange~-K-Ar'ages andbiochronologic signif'icance.

Geol.Soc.Americaab'stracts withprograms, Cordilleran Section,66thAnnualmeeting,v-2,no.2,(srithD.L.Turnerand,R.C.Surdam).GeologyoftheArroyoGrandequadrangle, SanLuisObispoCo.,Californa:C"lif-Div.ofNinesand.GeologyNapSheet24.~~GeologicmapoftheMorroBaySouthandportSanLuisquadrangles, SanLuisObispoCo.,California.

U.S.'eological.

Survey1G'11MapSeries.POligocene andMioceneFelsicVolcanism, NestCentra3.California CoastRanges,Amer,.Geophys.UnionIieeting, Fall,1973(abstract}

(~rith8.G.Ernst).197'974197032.33197<3)+.35-'975Shellgro;i-~hinTivelastultorum (Mawr,1823)andca11mechioneTL'nnaeue, 1(55Iaiva1via):

Annua1perxoc'city, latitudinal differences anddiminution

~withage,(rrith>T.A.DollaseandC.E.Corbato).

'Palaeo~eography, Palaeoclimatalogy..

Paleoecology.

v3.5>p.33>>61.GologyandPetrology ofheCambriaFelsiteaHetr03.i=ocen Formation

'tTestCentralCalif.CoastRanges.Geol.Soc.Amer.Bu13,v.U5>p523532'Nith7T.G.Ernst).Geo"og'I:aooftheCambriaRegion,.SanLu-sODispoCounty,California.

U.S.,Geological Survey,Miscellaneous F'eldStudiesMap599in1974.\Latiud,nalvariation inshellgrosrthpatternsofbivalve'mo3~uscs:

implications andproblems:

He@castle

.Symposium, Vol.;1974.Latitudinal variation inshellgrowthpatternsofbivalvemoI3.uses:

implications andproblems.

p.163-173InGrowthRhythmsandthehistoryoftheEarth'rotation, G.D.Rosenberg and.S.K.Runcorneds.John3/ileyandSons.36.1975Feldspathic GeodesHearBlackMountain, WesternSanLuisObispoCounty,California, Geol.Soc.Amer.,abstracts

~"ithprograms, Cordilleran Section,73.stAnnualI,"ecting, March,1975.(WithlT.G.Ernst)(ABSRACTe)~37-1975GeologicmapoftheCayucos-San Lui"Obisporepion.U.S-Geol.Surv.Misc.FieldStudiesMap,M;686C-4~~

i38.197539.197540.197541.197642.1976INPRESSINPRE-PARATIONFeIdsphicgeodesnearBlackMo&tain,westernLuisObispoCounty,California:

Amer.Min.,V.60,'.1105-1112.

(withM.G.Ernst)SanSimeon-Hosgri faultsystem,coastalCalifornia:economicand,environmentaIimpIications.U.S.Geological SurveyOpenFileRept.,75-533,12manuscript pages.SanSimeon-Hosgri faultsystem,'oastal California:economicandenvironmentaIimpIications.Science,v.190,'p.1291-1293.

GeologicMapoftheSanSimeon-Piedras BlancasRegion,SanLuisObispoCounty,California:U.S.GeologicaISurveyMisc.FieIdStudiesMap,MF784,scaleofI:24,000.

Originanddevelopment oftheLompoc-Santa Hariapull-apart BasinanditsrelationtotheSanSimeon-HosgriFault,California:Geological SocietyofAmerica(ABSTRACT)

GeologicMapoftheSantaHariaValleyRegion,Santa"BarbaraCounty,California:U.S.Geological Survey.Misc.FieldStudiesMap,scaleofI:24,000.

Cerozoicbas'ins,CentraICaIifornia,(Probably'alifornia DivisionofHineswiII,publishGSASy-posium papers(seeabstract4'42forgeneraldi'scussion).

r~~{<~q~

~~p~ATTACHMENT DStephanAlanGraham2136Greenwood Dr.SanCarlos,CA94070GeneralBorn4/25/50,Evansville, Indianahhrried5/27/72,wife-Pmela, 1childU.S.citizen,militarystatus-lH, foreignlanguage-German Education A.B.IndianaUniversity

.1972M.S.StanfordUniversity 1974Eh.D.StanfordUnivesity1976Geology,withHonorsGeologyIGeologySpecialization:

Sedimentary geology,inparticular sedimentary tectonics Thesis:addleTertiarypaleogeography andstructural development oftheSalinianblock,California; Eh.D.committee:

W.R.Dickinson (advisor),

J.C.Ingle,Jr.,B.M.Page51973:7.1976:Professional Ecperience l.1968,1970:Subsurface mapping,FritzOperating Co.,Ft.Branch,Ind.,(summers)2.1970:X-raydiffractometer technician, IndianaUniv.,Bloomington, Ind.,(part-time) 3.1971-1972:

Consulting geologist forPeninsula Exploration Co.,CorpusChristi,Texas,(part-time

)4.1972:Associate Instructor, IndianaUniversity GeologicFieldStation,Cardwell, hantana,(summer)Researchassistant, StanfordUniversity,

Stanford, Ca.,(summer'6.1973:Instructor, Stanf'ord Geological Survey,Bridgeport, Ca.,(summer)ResearchGeologist, ExxonProduction ResearchCo.,Houston,Texas8.1,976-Exploration Geologist, ChevronUSAInc.,SanFrancisco, CAAwards,1.2~3~5~6.7~8.Assistantships, andFellowships EarthSciencesFreshmanScholarship, IndianaUniversity, 1968ArthurR.hertzDistinguished Scholarship, IndianaUniversity, 1968-1972 IndianaUniversity GeologicFieldStationtuitionaward,1969StandardOilof'exasundergraduate geologyaward,1969,1970Beststudentpaper,RockyMtn.Section,Geol.Soc.America,1971Seniorfacultyscholarship award,3adianaUniversity, 1972%hiBetaKappa,1972NationalScienceFoundation GraduateFellowship, 1972-1975

~~2Professional Societies Geologica1 SocietyofAmericaSigmaXiSocietyoZconomicPaleontologists andMineralogists Publications Graham,S.A.,1971,Occurrence ofmiddleCambrianislandsinsouthwest

&ntana:Geol.Soc,AmericaAbs.withPrograms, RockyMtn.Section,383-384.Graham,S.A.,andSuttner,L.J.,1974,Occurrence ofmiddleCambrianislandsinsouthwest leant~a:%hebhuntainGeologist, v.11,71-84.Graham,S.A.,1974,Remanantmagnetization ofmoderntidalflatsediments fromSanFrancisco Bay,California:

Geology,v.2,223-226.Graham,S.A.,Dickinson, W.R.,andIngersoll, R.V.>1975,Himalayan-Bengal modelforflyschdispersal intheAppalachian-Ouachita system:Geol.Soc.AmericaBu11.,v.86,43,273-286.Dickinson, W.R.,andGraham,S.A.,1975,Sedimentary environments, depositional systemsandstratigraphic cyclesincurrentconceptsofdepositicnal systemswithapplications forpetroleum geology;W.R.Dickinson, editor:SanJo~uinGeological SocietyShortCourse,Bakersfield, 1-10.Graham,S.A.,1975,Tertiarysedimentary tectonics ofthecentralSa1inianblockofCalifornia:

Geol.Soc.AmericaAbstracts withprograms>

v.7,no.7,1089.Graham,S.A.,1976,Tertiarysedimentary tectonics ofthecentralSalinianblockofCalifornia:

Eh.D.Dissertation, StanfordUniversity,

Stanford, California, 510p.Graham,S.A.,1976,Tertiarystratigraphy anddepositional environments nearIndiansRanch,1hntereyCounty,California:

TheNeogeneSymposium, Pac.Sect.,Soc,Econ.P01eontologists and5!ineralogists, 125-136.Grahmn,S.A.,1976,Tertiarystratigraphy anddepositional environments nearIndiansRanch,bbntereyCounty,Ca1ifornia:

Amer.Assoc.ofMtroleumGeologists Bull.(abs.),2181-2182.

Graham,S.A.,1976,SanGregorioFaultasamajorright-slip faultoftheSanAndreasFaultsystem:Geol.Soc.AmericaAbstracts withPrograms, v.8,no.6,890.Graham,S.A.,Ingersoll, R.V.,andDickinson, W.R.,1976,Commonprovenance forlithicgrainsinCarbon'erous fromOuachitat~ountains andBlackWarriorBasin:JournalofSedimentary Petrology, v.46,620-632Dickinson, W.R.,Graham,S.A.,andIngersoll, R.V.,andJordanT.Z.,1976pApplication ofplatetectonics topetroleum geologyalongthePacificmarginofNorthAmerica:Aner.Assoc.Petroleum Geologists Bull.(abs),2179.Graham,S.A.,and.Dickinson, W.R.,1977,Apparentoffsetsofonl'andgeologicfeaturesacrosstheSanGregorio-Hosgri faulttrend:Geol.Soc.AmericaAbstracts withPrograms, v.9,no.4,424.Graham,S.A.,andDickinson, W.R.,1978,Apparentoffsetsofon1andgeologicfeaturesacrosstheSanGregorio-Hosgri faulttrend:Science,v.199,179-181.=D-2 Graham,S.A.,andDickinson, V.R.,1978,ApparentoffsetsofonlandgeologicfeaturesacrosstheSanGregorio-Hosgri faulttrend:Calif.Div.YiinesandGeologySpecialReport(inpress).Graham,S.A.,1978,RoleoftheSalinianblockintheevolution oftheSanAndreasfaultsystem:Amer.Assoc.Petroleum Geologists Bull.,v.62,gll(inpress).bTelephone (415)894-0308(office8:00AM-4:00PM.)(415)595-2036(home)

~~

Curriculum Vitae-Wm.R.Dickinson Born:Nashville, Tennessee, Oct.26,l931Degrees(allStanfordUniversity):

B.S.,Pet.Engr.1952M.S.,Geology1956Ph.D.,Geology1958USAF,1952-1954 FacultyPositions (allStanfordUniv.):ActingAssistant Professor Assistant Professor Associate Professor Professor 1958-601960-631963-681968-Present Guggenheim Fellow1965ArticlesinScience,Nature,'eol.

Soc.AmericaBull.,Jour.Geophys.Research, Am.JourSci.,Am.Assoc.Petroleum Geologists Bull.,Jour.Sediment.

Petrology, Sediment.

Geology,Tectonophysics, EarthandPlanetary Sci.Lettrs.,Rev.Geophysics andSpacePhysics,Can.Jour.EarthSci.MemberofGeol.Soc.America(Fellow),

Am.Assoc.Petroleum Geologists, Am.Geophys.Union,Soc.Econ.Paleontologists andHineralogists, Nat.Assoc.GeologyTeachers, Am.Assoc.Adv.Sci.Chairman, Cordilleran Sec.,Geol.Soc.America(1974-1975);

President, Peninsula Geol.Soc.(1977-1978);

Councillor, Geol.Soc.America(1977-1980).

A.I.LevorsenMemorialAward,Pac.Sec.,Am.Assoc.Petroleum Geologists (1978-1979)

.MaorConference Particiation1966-speaker,Symposium onCircum-Pacific Orogenesis, PacificScienceCongress, Tokyo,Japan.1967-co-convener, JointUSGS-Stanford'Conference onGeologicProblemsofSanAndreasFaultSystem,StanfordUniversity.

1967-speaker,IUGG-IAVConference onAndesites, OregonInstitute forVolcanology.

1969-speaker,AndesiteSymposium, VolcanicStudiesGroup,Geological SocietyofLondon.1969-convener, GSAPenroseConference onPlateTectonics andOrogenicBelts,Asilomar, California.

1970-co-organizer, Symposium onCretaceous GeologyofCentralCalifornia, GSACordilleran SectionMeeting,Hayward,California,.

~(~~~~1971-co-organizer andspeaker,NASSymposium onPlateTectonics, Washington, D.C.1971-keynotespeaker,Symposium onPetrology andGeochemistry ofIslandArcsinRelationtoTectonicEnvironment, PacificScienceCongress,

Canberra, Australia.

1971-organizer andkeynotespeaker,Symposium onPlateTectonics inGeologicHistory,NationalGSAmeeting,Washington, D.C.1972-speaker,CarnegieInstitute Conference onPlateTectonics andthe'volution ofContinents, Airlie,Virginia.

1972-speaker,JointNSP-Wisconsin Conference onAncientandModernGeosynclinal Sedimentation, Madison,Wisconsin.

1973-convener, SEPMResearchSymposium onTectonics andSedimentation, AAPG-SEPM Nat.Mtg,,Anaheim,California.

1974-speaker,GACSymposium onVolcanicGeologyandMineralization intheCanadianCordillera, Vancouver, Canada.1974-convenorandspeaker,SanJoaquinGeological SocietyShortCourseonPlateTectonics andPetroleum Geology,Bakersfield, California.

1975-convenorandspeaker,SanJoaquinGeological SocietyShortCourseo'Depositional SystemsandPetroleum Geology,Bakersfield, California.

1975-Speaker,Symposium onCircum-Pacific Magmatism, Metamorphism, andSedimentation, PacificScienceCongress, Vancouver, Canada.1976-invitedspeaker,EwingSymposium ofLamont-Doherty Geological Observatory,

Harriman, NewYork.1976-convenorandspeaker,Symposium onPre-Tertiary ofBlueMountains

Province, GSACordilleran SectionMeeting,Pullman,Washington.

1976-instructor, AAPGShortCourseonPlateTectonics andHydrocarbon Accumulation, AAPGNationalMeeting,NewOrleans,Louisiana.

1976-speaker,SEGShortCourseonPlateTectonics andSedimentary Basins,SEGNationalMeeting,Houston,Texas.1977-speaker,Symposium onPaleozoic Paleogeography ofthePacificCoast,PacificSectionSEPMMeeting,Bakersfield, California 1977-speaker,AAPGShortCourseonContinental Margins,AAPGNationalMeeting,Washington, D.C.1978-keynotespeaker,International Geodynamics Conference ontheWesternPacific,Tokyo,Japan.E-2 Is1l1978-speaker,Symposium onMesozoicPaleogeography ofthePacificCoast,PacificSectionAAPGMeeting,Sacramento, California.

E-3 ListofPublications inGeoloicalSciencebWilliamR.Dickinson WRD,WRD,1958,Mesozoicmarineclasticrocksofvolcanicderivation insouthwestern GrantCounty,Oregon(abs}:Geol.Soc.AmericaBull.,v.69,p.1554.1959,Structural relationships ofChurchCreekandWillowCreekFaults,SantaLuciaRange,California (abs.):Geol.Soc.AmericaBull.,v.70,p.1715.1960,GeologyoftheIzeearea,GrantCounty,Oregon(abs):Dissert.Abs.,v.20,no.11(1958Ph.D).1960,Petrology ofJurassicmarinetuffs,centralOregon(abs)':Geol.Soc.AmericaBull.,v.71,p.2056.1961,Jurassicandesitic provincealongthePacificmarginofNorthAmerica(abs):Geol.Soc.AmericaAbs.for1961,p.19.1962,Brecciated serpentine extrusion onTableMountainincentralCalifornia CoastRanges(abs).:Geol.Soc.AmericaAbs.for1962,p.34.1962,Marinesedimentation ofclasticvolcanicstrata(abs):AmericanAssoc.Petroleum Geologists Bull.,v.46,p.263.1962,Hetasomatic quartzkeratophyre incentralOregon:Am.Jour.Sci.,v.260,p.249-266.1962,Petrology anddiagenesis ofJurassicandesitic strataincentralOregon:Am.Jour.Sci.,v.260,p.481-500.1962,Petrogenetic significance ofgeosynclinal andesitic volcanism alongthePacificmarginofNorthAmerica:Geol.Soc.AmericaBull.,v.73,p.1241-1256.

1963,Tertiarystratigraphic sequenceoftheHancockRancharea,MontereyandKingsCounties, California:

Pac.Sec.Am.Assoc.Petroleum Geologists-Soc.Econ.Paleontologists andHineralogists Ann.Field TripGuidebook toGeologyofSalinasValleyandSanAndreasFault,p.47-53.WRDandL.W.Vigrass,1964,Pre-Cenozoic historyofSuplee-Izee

district, Oregon:.implications forgeosynclinal theory:Geol.Soc.AmericaBull.v.75,p.1037-1044.

WRD,1965,FoldedthrustcontactbetweenFranciscan rocksandPanacheGroupintheDiabloRangeofcentralCalifornia (abs):Geol.Soc.AmericaSpecialPaper82,p.248-249.WRDandL.W.Vigrass,1965,MesozoichistoryofSuplee-Izee

district, centralOregon(abs):Geol.Soc.AmericaSpecialPaper82,p.325.WRDandJ.G.Smith,1965,Geological relations oftheKoroimavua Groupinnorthwest VitiLevu:FijiGeol..SurveyDept.Note121,4p.WRDandJ.G.Smith,1964,Geological roadlogfromNandiInternational AirporttotheNausoriHighlands:

FijiGeol.SurveyDept.Note122,6p.E-4

~~~Publications, WilliamR.Dickinson PagetwoSmith,J.G.andWRD,1965,Ageological reconnaissance ofthesouthernYa'sawaIslands:FijiGeol.SurveyDept.Note125,6p.WRDandL.W.Vigrass,1965,GeologyoftheSuplee-Xzee area,Crook,Grant,andHarneyCounties, Oregon:Ore.Dept.GeologyandMineralIndustries Bull.No.58,109p.WRD,1965,Tertiarystratigraphy oftheChurchCreekarea,'onterey County,California:

Calif.Div.MinesandGeologySpecialRpt.86,p.25-44.WRD,1966,Problemsofstratigraphic nomenclature inFiji(South-West PacificGeological SurveyConference Paper):FijiGeol.Survey'G.S.Note9/66,10p.WRD,1966,TableMountainserpentinite extrusion inCalifornia CoastRanges:Geol.Soc.AmericaBull.,v.77,p.451-472.WRD,1966,Structural relationships ofSanAndreasfaultsystem,CholameValleyandCastleMountainRange,California:

Geol.Soc.AmericaBull.,v.77,p.707-726.WRD,1966,Petrography ofspecimens fromtheMamanutha Group:FijiGeol.SurveyDept.G.S.Note20/66,5p.WRDandD.R.Lowe,1966,Stratigraphic relations ofphosphate-andgypsum-bearingupperMiocenestrata,upperSespeCreek,VenturaCounty,California:

Am.Assoc.Petroleum Geologists Bull.,v.50,p.2464-2470.

WRD,1967,Circum-Pacific andesitetypes(abs):Am.Geophys.Un.Trans.,v.48,p.253.WRDandTrevorHatherton, 1967,Andesitic volcanism andseismicity aroundthePacific:Science,v.157,p.801-803.WRD,1967,Tectonicdevelopment ofFiji:Tectonophysics, v.4,p.543-553.WRD,1967,ProblemsMstratigraphic nomenclature inFiji(abs):N.Z.Jour.GeologyandGeophysics, v.10,p.1181-1182.

WRD,1968,Circum-Pacific andesitetypes:Jour.Geophys.Res.,v.73,p.2261-2270.

WRDandArthurGrantz(eds),1968,Proceedings ofconference ongeologicproblemsofSanAndreasfaultsystem:StanfordUniv.Pub.Geol.Sci.,v.11,375p.WRD,1968,Sedimentation ofvolcaniclastic strataofthePlioceneKoroimavua Groupinnorthwest VitiLevu,Fiji:Am.Jour.Sci.v.266,p.440-453.IHatherton, TrevorandWRD,1968,Andesitic volcanism andseismicity inNewZealand:Jour.Geophys.Res.,v.?3,p.4615-4619.

WRD,M.J.Rickard,F.X.Coulson,J.G.Smith,andR.L.Lawrence, 1968,LateCaenozoic shoshonitic lavasinnorthwestern VitiLevu,Fiji:Nature,v.219,p.148.E-5 Publicons,WilliamR.Dicki~>>;on Paget)treeWRD,1968,Comparison ofCalifornia's Franciscan assemblage andGreatValleysequencetoNewZealand's axialandmarginalfacies(abs):Geol.Soc.AmericaSpecialPaper115,p.322.WRD,1968,Singatoka dunesands,VitiLevu,Fiji:Sed.Geology,v.2,p.115-124.WRD,1968,Blendofteachingandresearch(letter):

Science,v.162,p.1221.Noble,D.C.,WRD,andClark,M.M.,1969,CollapsecalderaintheLittleWalkerarea,MonoCounty,California (abs):Geol.Soc.AmericaSpecialPaper121,p.536-537.Rich,E.I.,R.W.Ojakangas, WRD,andWinSwe,1969,Sandstone petrology ofGreatValleysequence, Sacramento Valley,California (abs):Geol.Soc.AmericaSpecialPaper121,p.550.WRD,R.W.Ojakangas, andR.J.Stewart,1969,Burialmetamorphism ofthelateMesozoic'reat Valleysequence, CacheCreek,California:

Geol.Soc.AmericaBull.,v.80,p.519-525.WRD,1969,Evolution ofcalc-alkaline rocksinthegeosynclinal systemof.California andOregon,p.151-156inMcBirney, A.R.(ed),Proceedings ofandesit'e conference:

Ore.Dept.GeologyandMineralIndustries Bull.65,193p.InPac.Sec.Soc.Econ.Paleontologists andMineralogists, 1969,FieldTripGuidebook (WRD,ed):GeologicsettingofupperMiocenegypsumandphosphorite

deposits, upperSespeCreekandPineMountain, Ventura'ounty,California, 91p.:(a)(b)(c)(d)WRD(p.1-24),Geologicproblemsinthemountains betweenVenturaandCuyama.WRD(p.49-55),Miocenestratigraphic sequenceonupperSespeCreekandPineMountain.

WRD(p.63),quaternary terracegravelsandcolluvium onsouthsideofPineMountain.

WRD(p.68-77),Roadlog,Ojai.toOzena.Hatherton, TrevorandWRD,1969,Therelationship betweenandesitic volcanism andseismicity inIndonesia, theLesserAntilles, andother,i.sland arcs:Jour.Geophys.Res.,v.74,p.5301-5310.

Swe,WinandWRD,1970,Sedimentation andthrusting oflateMesozoicrocksintheCoastRangesnearClearLake,California:

Geol.'oc.

AmericaBull.,v.81,p.165-188.WRD,1970,Tectonicsettingandsedimentary petrology oftheGreatValleySequence(abs):Geol.Soc.AmericaAbs.withProgs.;v.2,p.86-87.Gilbert,W.G.andWRD,1970,Stratigraphic variations insandstone petrology, GreatValleySequence, centralCalifornia coast:Geol.Soc.AmericaBull.,v.81,p.949-954.E-6

~~Publi.ons,Wflliamk.Dickinson PagefourlWRDandPage,B.M.,1970,CentralCalifornia CoastRanges:GuidetoFieldTripNo.1,Cordilleran Sec.,Geol.Soc.AmericaAnn.Mtg.1970,25p.WRD,1970,Thenewglobaltectonics (report:2ndPenroseConference):

Geotimes, v.15,no.4,p.18-22.WRDl1970,Globaltectonics (report:2ndPenroseConference):

Science,v.168,p.1250-1259.

WRD,1970,Interpreting detritalmodesofgraywacke andarkose:Jour.Sed.Petrology, v.40,p.695-707.1970,Relations ofandesitic volcanicchainsandgraniticbatholith beltstothedeepstructures oforogenicarcs:Geol.Soc.LondonProc.,no.1662,p.27-30.1970,Geologyandgeologists inregionalplanning(abs):Geol.Soc.AmericaAbs.withProgs.,v.2,p.738-739.WRD,1970,GeologyfortheMasses:Jour.Geol.Education, v.18,p.194-197.1970970,Relations ofandesxtes,

granites, andderivative sandstones toarc-trench tectonics:

Rev.Geophys.andSpacePhys.,v.8,p.813-862;WRD,1971,DetritalmodesofNewZealand"graywackes:

Sed.Geology,v.5,p.37-56.1971,Platetectonics (developments during1970):Geotimes, v.16,p.21.1971,Platetectonicmodelsofgeosynclines:

EarthandPlanet.Sci.Lettrs.,v.10,p.,165-1?4.

1971,Clasticsedimentary sequences deposited inshelf,slope,andtroughsettingsbetweenmagmaticarcsandassociated trenches:

Pac.Geology,v.3,p.15-30.WRD19?9?1,Platetectonicmodelsfororogenyatcontinental margins:Nature,v.232,p.41-42.WRD,1971,Complementarity (letter):

Science,v.173,p.1191-1192.

WRD,1971,Ecological questionnaire (letter):

NaturalHistory,v.80,no.2,p.101.WRD1971R971,Reconstruct@on ofpastarc-trench systemsfrompetrotectonic assemblages inislandarcs(abs):12thPac.Sci.Congr.Proc.,v.1,p.445.WRD,1971,Platetectonics ingeologichistory:Science,v.174,p.107-113.WRD,1971,Evidenceforplatetectonicregimesinthepast:Geol.Soc.AmericaAbs.withProg.,v.3,p.544.WRDandW.C.Luth,1971,Amodelforplatetectonicevolution ofmantlelayers:Science,v.174,p.400-404.E-7 Publicana, WilliamR.Dickinr~nn PagefiveWRD,D.S.CowanandR.A.Schweickert, 1972,Testofnewglobaltectonics (discussion):-

Am.Assoc.Petroleum Geologists Bull.,v.56,p.375-384.WRD,1972,TheEarthSciences(secondedition),

A.N.Strahler(review):

Am.Geophys.Un.Trans.(EOS),v.53,p.258-260.Wright,R.M.andWRD,1972,Provenance ofEocenevolcanicsandstones ineasternJamaica;apreliminary note:Carib.Jour.Sci.,v.12,p.107-113.WRD,1972,Platetectonics symposium (preface):

Am.Jour.Sci.,v.272,p.549-550.WRD,1972,Evidenceforplate-tectonic regimesintherockrecord:Am.Jour.Sci.,v.272,p.551-576.WRD,1972,Dissected erosionsurfacesinnorthwest VitiLevu,Fiji:Zeitschr.

f.Geomorph.

N.F.,v;16,p.252-267.Hedge,C.E.,Samoa:WRDandE.I.Valleyv.83,Z.E.Peterman, andWRD,1972,Petrogenesis oflavasfromWesternGeol.Soc.AmericaBull.,v.83,p.2709-2714.

Rich,1972,Petrologic intervals andpetrofacies intheGreatsequence, Sacramento Valley,California:

Geol.Soc.AmericaBull.,p.3007-3024.

Mader,G.G.,E.A.Danehy,J.C.Cummings, andWRD,1972,Landuserestrictions alongtheSanAndreasfaultinPortolaValley,California, p.845-858inSherif,M.A.andR.C.Bostrom(eds),Proceedings oftheInternational Conference onMicrozonation foxSaferConstruction, Seattle,Wash.,987p.WRD,1973,Tettonica azolleecatenemontuose, art.10,p.190-'200inEnciclopedia dellascienzaedellatecnica73:Edizioniscientifiche etechniche, Mondadori, Milano,Italy.WRD,1973,Widthsofmodernarc-trench gapsproportional topastdurationofigneousactivityinassociated magmaticarcs:Jour.Geophys.Res.,v.78,p.3376-3389.

WRD,1973,Reconstruction ofpastarc-trench systemsfrompetrotectonic assemblages intheislandarcsofthewesternPacific,p.569-601inColeman,P.J.'ed),

ThewesternPacific;islandarcs,marginalseas,geochemistry:

Univ.WesternAustralia Pxess,Perth,601p.WRD,1974,Reviewofarcvolcanism (abs):Geol.Assoc.CanadaCordilleran Sec.Programme andAbstracts, p.9-10.InWRD(ed),1974,Geologicinterpretations fromglobaltectonics withapplica-tionsforCalifornia geologyandpetroleum exploration:

SanJoaquinGeological SocietyShortCourse,Bakersfield, 75p.(a)WRD(p.2-1to2-5),Geologicimplications ofplatetectonics.

(b)WRD(p.9-1to9-6),Platetectonics andsedimentary basins.(c)WRD(p.15-1to15-4),Platetectonics andmigration ofpetroleum.

E-8 Publicas,WilliamR.Dickinson PagesixNoble,D.C.,D.B.Slemmons, M.K.Korringa, WRD,YehyaAl-Rawi,andE.H.McKee,1974,EurekaValleyTuff,east-central California andadjacentNevada:Geology,v.2,p.139-142.WRD,1974,Sedimentation withinandbesideancientandmodernmagmaticarcs,p.230-239inDott,R.H.,Jr.,andR.H.Shaver(eds),Modernandancientgeosynclinal sedimentation:

Soc.Econ.Paleontologists andMineralogists SpecialPub.No.19,380p.Baldwin,.

Brewster, P.C.Coney,"andWRD,1974,DilemmaofaCretaceous timescaleandratesofsea-floor spreading:

Geology,v.2,p.267-270.WRD,1974,Subduction andoilmigration:

Geology,v.2,p.421-424.WRD,1974,Platetectonics andsedimentation, inDickinson, W.R.(ed),Tectonics andsedimentation:

Soc.Econ.Paleontologists andMineralogists SpecialPub.No.22,p.1-27.WRD,1974,Islandarcs;Japananditsenvirons(review):

Jour.Geologyv.82,p.529.WRD,1975,Potash-depth (K-h)relations incontinental marginandintraoceanic magmaticarcs:Geology,v.3,p.53-56.InWRD(ed),1975,Currentconceptsofdepositional systemswithapplications forpetroleum geology:SanJoaquinGeological SocietyShortCourse,Bakersfield, 105p.(a)(b)(c)(d)WRDandS.A.Graham(p.O-lto0-10),Sedimentary environments, depositional systems,andstratigraphic cycles.WRD(p.1-1,to1-16),Fluvialsediments ofstreamvalleysandalluvialfans.WRD(p.5-1to5-8),Deltaicdepositsandcyclothems.

WRD(p.12-1to12-4),Hydrocarbon occurrences inrelationtodepositional systems.Graham,S.A.,WRD,andIngersoll, R.V.,1975,Himalayan-Bengal modelforflyschdispersal inAppalachian-Ouachita system:Geol.Soc.AmericaBull.,v.86,p.273-286.WRD,1975,Problemsofpre-Tertiary tectoniccorrelations acrossthePacificNorthwest (abs):Geol.Soc.AmericaAbs.withProgs.,v.7,p.604.WRD,1975,Geologyandoil(review):

Science,v.189,p.133-134.WRD,1975,Time-transgressive tectoniccontactsbordering subduction complexes (abs):Geol.Soc.AmericaAbs.withProgs.,v.7,p.1052.Snyder,W.S.,WRD,andM.L.Silberman, 1975,Tectonicimplications ofspace-timepatternsofCenozoicmagmatism inthewesternUnitedStates(abs):Geol.Soc.AmericaAbs.withProgs.,v.7,p.1279.E-9 44~Publicns,WilliamR.Dickinson PagesevenWRD,1975,Sedimentary basinsdeveloped duringevolution ofMesozoic-Cenozoic arc-trench systeminwesternNorthAmerica(abs):-13thPacificSci.Congr.Abs.,p.397-398.NWRDandW.S.Snyder,1975,Geometryoftriplejunctions andsubducted litho-sphererelatedtoSanAndreastransform activity(abs):Am.Geophys.Un.Trans.(EOS),v.56,p.1066.WRD,K.P.Helmold,andJ.A.Stein,1976,Paleocurrent trendsandpetrologic variations inMesozoicstratanearSouthForkofJohnDayRiver,centralOregon(abs):Geol.Soc.AmericaAbs.withProgs.,v.8,p.368-369.WRD,1976,Sedimentary basinsdeveloped duringevolution ofMesozoic-Cenozoic arc-trench systeminwesternNorthAmerica:Can.Jour.EarthSci.,v.13,p.1268-1287.

Snyder,,W.S.,

WRD,andSilberman, M.L.,1976,Tectonicimplications ofspace-timepatterns.ofCenozoicmagmatism inthewesternUnitedStates:EarthPlanet.Sci.Lettrs.,v.32,p.91-106.Graham,S.A.,R.V.Ingersoll, andWRD,1976,Commonprovenance forlithicgrainsinCarboniferous sandstones fromOuachita-Mountains andBlackWarriorBasin:Jour.Sed.Petrology, v.46,p.620-632.WRD,1976,Platetectonics andhydrocarbon accumulation:

Am.Assoc.Petroleum Geologists Continuing Education CourseNoteSer.No.1,61p.Graham,S.A.andWRD,1976,SanGregoriofaultasamajorright-slip faultoftheSanAndreasfaultsystem(abs):Geol.Soc.AmericaAbs.withProgs.,v.8,p.890.Ingle,J.C.,Jr.,S.A.Graham,,andWRD,1976,Evidenceandimplications ofworld-wide latePaleogene climaticandeustaticevents(abs):Geol.Soc.AmericaAbs.withProgs.,v.8,p.934-935.WRD,1976,Thewaytheearthworks;anintroduction tothenewglobalgeologyanditsrevolutionary development (review):

Jour.Geology,v.84,p.502.Casey,T.A.L.andWRD,1976,Sedimentary serpentinite oftheMioceneBigBlue.Formation near,CantuaCreek,California (abs):Am.Assoc.Petroleum Geologists Bull.,v.60,p.2177.WRD,S.A.Graham,R.V.Ingersoll, andT.E.Jordan,1976,Applications ofplatetectonics topetroleum geologyalongthePacificmarginofNorthAmerica(abs):Am.Assoc.Petroleum Geologists Bull.,v.60,p.2179.Casey,T.A.L.andWRD,1976,Sedimentary serpentinite oftheMioceneBigBlueFormation nearCantuaCreek,California, inFritsche, A.E.H.TerBest,Jr.,andW.W.Wornardt(eds),.TheNeogeneSymposium:

Pac.Sec.Soc.Econ.Paleontologists andMineralogists Ann.Mtg.,p.65-74.WRD,1977,Fossilfuelsandcontinental drift:Basterfield Lec.Ser.No.19,Univ.Regina,Saskatchewan, 16p.

Publfcons,WilliamR.Dickinson Pagee5ghtGraham,S.A.andWRD,1977,Apparentoffsetsofon-landgeologicfeaturesacrosstheSanGregorio-Hosgri faulttrend(abs):Geol.Soc.AmericaAbs.withFrogs.,v.9,p.424.Ingersoll, R.V.,E.I.Rich,andWRD,1977,GreatValleySequence, Sacramento Valley:Cordilleran Sec.Geol.Soc.AmericaFieldTripGuide,73p.WRD,1977,Paleozoic platetectonics andtheevolution oftheCordilleran continental margin,inStewart,J.H.,C.H.Stevens,andA.E.Fritsche(eds),Paleozoic paleogeography ofthewesternUnitedStates:PacificSec.Soc.Econ.Paleontologists andMineralogists PacificCoastPaleo-geography Symp.1,p.137-156.WRDandD.R.Seely,1977,Forearcstratigraphy andstructure:

9thAnn.OffshoreTechnology Conf.Paper2889,Houston,Tex.,p.101-106.D.R.SeelyandWRD,1977,Structure andstratigraphy offorearcregions:Am.'Assoc.Petroleum Geologists Continuing Education CourseNoteSeriesNo.5,p.Cl-C23.WRDandD.R.Seely,1977,Stratigraphy andstructure ofcompressional continental margins(abs):Am.Assoc.Petroleum Geologists Bull.,v.61,p.781.WRD,1977,Tectono-stratigraphic evolution ofsubduction-controlled sedimentary assemblages, inTalwani,ManikandW.C.Pitman III(eds),Islandarcs,deepseatrenches, andback-arcbasins:Am.Geophys.Un.MauriceEwingSer.1,p.33-40.WRD,1977,Subduction zones:EarthScienceRev.,v.13,p.7071Packer,D.R.,>TRD,andK.M.Nichols, 1977,MemorialtoMarjorieK.Korringa, 1943-1974:

Geol,Soc.AmericaMemorials, 3p.WRD,1977,Subduction tectonics inJapan:Am.Geophys.Un.Trans.(EOS),v.58,p.948-952.WRD'ndW.S.Snyder,1977,InferredplatetectonicsettingofclassicLaramideorogeny(abs):Geol.Soc.AmericaAbs.withProgs.,v.9,p.950.Graham,S.A.andWRD,1978,Evidencefor115kilometers ofrightslipontheSanGregorio-Hosgri faulttrend:Science,v.199,p.179-181.Howard,A.D.andWRD,1978,Volcanicenvironments, chap.9inHoward,A.D.andIrwinRemson(eds.),Geologyinenvironmental planning:

McGraw-Hill, N.Y.,p.246-274.WRDandT.P.Thayer,1978,Paleogeographic andpaleotectonic implications ofMesozoicstratigraphy andstructure intheJohnDayinlierofcentralOregon,inHowell,D.G.andK.A.McDougall (eds),Mesozoicpaleogeography ofthewesternUnitedStates:PacificSec.Soc.Econ.Paleontologists andMineralogists PacificCoastPaleogeography Symposium 2,p.147-162.

4I'l 1~~Is'~Xnpress,tobeHosgriFaultZE.A.SilvereW.Mines&Geology,ublishedin"SanGregory-.io-California,"

editedbyNewmark,Calif.Div.ofSpecialReport137.TheSanGregorio-Hoser iFaultZone:AnQverviewEliA.SilverEarthSciencesBoardUniversity ofCalifornia SantaCruz,CA95064TheSanGregorio-Hosgri faultzoneispartofthelargerSanAndreasfaultsysteminCali.fornia.

thatformsthemajorlocusofshearduetomovementbetweenthePacificandNorth'American plates.Anenormousamountofefforthasbeenandispresently beingdevotedtostudyoftheSanAndreasfau1.titelf,andinrecentyearsoffsethistory,se'ismici',

increased dramatically (seedetailedquantitative knowledge ofandpresent-day'ovement hasforexampleKovachandNur,1973;Crowell,1975;Dickinson andGrntz,1968).Theextentofourknowledge ofotherfaultsoft:heSanAndreassystemismuchlesscomplete, dueinparttothelowerfrequency ofgreatearthquakes andsmalleroffsetonsubsidiary faults(andthrefore,perhap,lesserinterestinthesefaults)./'Anotl>er reasonmaybethelocationofsomeofthesubsidiary faults.TheSanGregorio-Hoseri faultzoneislocatedalongthecoastline southofSanFrancisco foralengthofnearly400km,andmuchofitliesjustoffshorewhereitisdifficult tostudy.Majoroutstandin.,

problemsofthisfaultzoneincludethedet:ailsoffaultlocation, continuity betweentheSanGregorioandHosgrif'auldsegments, offsethistoryoneachsegment,evidenceforHo1ocenemovement:s, andsei.i'oicity, These 1~~~e4Iproblemshave'mportance bothfortheirtectonicimplications andtheirbearingonanalysisofseismichazard.forcoastaldeveLopment andpower-plant siting.Thepapersinthisvolumewerepresented aspartofasymposium ontheSanGregorio-Hnsgri faultzoneattheCordilleran sectionmeetingoftheGeological SocietyofAmrica,inSacramento inApril,1977.Notallofthosepapers.are'eproduced herebutthosewhichfollowgiveagoodoverviewofthepresentstateofknowledge ofthisfaultzone.ClarkandBrabbdiscussthedetailedstratigraphy oneitherrsideoftheSanGregoriofaultinitstypearea.Theircarefulobservations offundamental stratigraphic differences, implysignificant differences insedimentation andtectonichistoryoneithersideofthefault.GrahamandDickinson usethis'Iandotherregionaldatatoinferupto115kmofrightlateraloffset.on,thefaultsinceMiocenetime.Thisfigureislargerthananearliersuggestion ofSOto90km(Siver,1974)basedonoffsetbasementterranesusingoffshoregeophysical control.~~Anestimateof80to100lanofpostMiocenerightLateralAoffsetontheHosgrifault(Hall,1975)tiesrathernicelywiththeaboveestimates fortheSanGregoriose~ent,buttheHosgriestimatehasbeenquestioned (Hamilton andVillingham, 1977).Hall(thisvolume)brieflyaddresesthesequestions andproposesapull-apart originfox'heSantaMariabasinonshore.Thequestionofcontinuity oftheSanGrcgorio-IIosgri faultzonefocusesonfourproblemareas:PointSur,CapeSanF-2

~~Martin,.SanSimeon,andsouthofPointSal(Fig.1).ThePointSurregionisdiscussed indetailbyGrahamandDickinson.

Theirinterpretation thattheSanGregorioprobablyconnectswiththeSurfaultissupported bydetailedgravitystudies(Woodson, 1973)andarguesagainstaprevioussuggestion thatthemainSanGregoriofaulttraceturnsinlandsouthofMontereytojointhePaloC'olorado fault(Greeneandothers,1973}.Hall(1975)firstsuggested thattheSanSimeonfaultispartoftheHosgrifaultzone(Fig.2).Thedetailedconnection betweentheHosgriandSanSimeonfaultshasnotbeenestablished andsomemapsshowan'en-echelon offsetbetweenthesefaults(Hall,1975;McCulloch andothers,1977).TheSanSimeon(Hosgri)segmenttrendsoffshoretothenorthtowardCapeSanMartin(Fig.2}.Recentlyflownaexomagnetic data(USGS-Calif.

DivisionofHinesandGeologyunpublished data)revealahighamplitude anomalytrendingnorthwest acrossCapeSanMartinandseemtorequiretheHosgri-San Simeonfaulteithertobendaroundtheanomaly(Fig.2)ortostep0hninlandtoafaultboundingtheeastsideoftheanomaly.IfthefaultbendsaroundthisanomalyitcouldjoinamajoroffhorefaultnorthofCapeSanMartin(McCulloch andothers,1977}thattrendstowardthe'Surfault(Fig.2).HcCulloch andothers(1977)(theirFig.2)showanorthwest trendingfaultwestofPointSur(Fig.1)whichtheyextendsoutheastward tothecoast;cuttingacrossandseparating theflosgriandSurfaults.Thisinterpretation wouldimplyadefinitelackofcontinuity between

't'eSanGregorioand.Hosgri faultsinthisarea.However,theirnorthwest trendingfaultmustcrossahighamplitude magneticanomalythatliesparalleltothecoast(anomalyMboundedby-1.5nTcontourinFig.2)andthisanomalyshowsnoevidenceofacrosscutting structure.

TheanomalyalsotrendsparalleltotheSurandHosgrifaultsandmaybecausedbyserpentine intrusions alongthefault.Structural relations inthisnearshore areaareobscuredbysurfaceslumping(NcCulloch andothers.-theirFig.2),andT.concludethatthebulkofevidenceatpresentfavorsoratleastallowscontinuity betweentheSurandHosgrifaults.Thesouthernextension oftheHosgriisalsoindispute.YicCulloch andothers(1977)mapthefaultsouthofPt.Argukllo, butHamiltonandHillingham (1977),usingmuchthesamedata,mapitnofarthersouththanoffshorePointSal.Eitherversionraisesgeometrical problemsofendingafaultwithapproximately 100kmoflateCenozoic.c

'lateraloffset.Uarioussolutions tothisproblemhavebeenproposedinoralcommuni-'cations, including abendofthefaultintotheTransverse rangeswherethemotionwouldbetakenupincompression (D.NcCulloch, oralcommun.,1977;llamilton andHillingham, 1977)oranoffs'etofthefaultbyeast-trending faultsinthoSantaBarbararegion(J.Crouch,oralcommun.,1976).Satisfactory fielddocumntation,howe.vcr, hasnotbeenreportedandthisremainsanouttandingstructural problem.Holocenemovemcnt.,

arewelldocumcntcd fortheSanGrcgoriofault(HeberandIajoie,1977;Coppersmitl>andGriggs,this 1~IL~~volume),andstudiesofseismicity confirmthepresent-day activityonboththeHosgriandSanGxegoriosegments(Gawthrop, 3.975andthisvolume).Thisinformation iscriticaltoanyplanneddevelopment alongthecentralCalifornia coastbecausetheSanGregorio-Hosgri isverynearlyacoastline faultovermostofitslength..TheSanGregorio-Hosgri appearstobthe'argest ofthe4subsidiary

'faultswithintheSanAndreassystem,bothinlength~andoffset.Otherfaults,suchastheHayward-Calaveras andRinconada havelesserdocumented offsetbutalsoplayan/important roleinthetectonicdevelopment oftheCalifornia coastrangesandaredeserving ofintensive study.F-5 References CitedCrowell,J.C.(Ed.),1975,SanAndreasfauLt.insouthernCalifornia:

California DivisionofHinesandGeologySpecialReport118,272p.Dickinson, W.R.,andGrantz,,A.(Eds.),1968,Proceedings

.oftheconference ongeologicproblemsofSanAndreasfaultsystem'Stanford Univ.Pubs.Geol.Sci.,v.11,374p.Gatothrop, William,'975, Seismicity ofthecentralCalifornia coastal'region:

U.S.Geol.SurveyOpen-file Report75-134,87p.\Greene,H.G.,Lee,V.H.K.,McCulloch, D.S.,andBrabb,E.E.,1973,.Faultsandearthquakes intheMontereyBayregion,California:

U.S.Geol.SurveyMisc.FieldStudyM.F.-518,14p.Hall,C.A.,Jr.,1975,SanSimeon-Hosgri faultsystem,coastalCalifornia:

economicandenvironmental implications:

Science,v.190,p.1291-1294.

Hamilton, D.H.,andWillingham, C.R.,1977,Hosgrifaultzone',structure,.

amountofdisplacement, andrelationship tostructures ofthewesternTranverse ranges:Geol:Soc.AmericaAbs.withprograms, v.9,no.4,p.429.Kovach,R.L.,andNur;Amos(Eds.),1973,Proceedings oftheconference onteet.onicproblemsoftheSanAndreasfaultsystem:StanfordUniv.Pub"-Geo'L.Sci.,v.11,494p.HcCulloch, D.S.,Clarke,'.

H.,Jr,Fic.ld,H.E.,Scott,E.W.,F-6

'l~~l~~~'7WandUtter,P.H.,1977,Asummaryreportontheregionalgeology,petroleum potential, andenvironmental geologyintheareaofproposed'ease sale'53-A,centralandnorthernCalifornia outercontinental shelf,partA,39p.Silver,E.A.,1974,Structural interpretation fromfree-airgravityontheCalifornia continental margin,35to40N:Geol.Soc.AmericaAbs.withprograms, v.6,no.3,p.253.Weber,G.E.,andLajoie,K.R.,1977,Late'Pleistocene andHolocenetectonics oftheSanGregoriofaultzonebetweeneMossBeachandPointAnoNuevo,SanMateoCounty,Cali,-fornia:Geol.Soc.AmericaAbs.withprograms, v.9,no.,4,p.524.~Hoodson,N.B.,III,1973,Abottomgravitysurvey-ofthecontinental shelfbetweenPointLobosandPointSur,California:

Thesis,NavalPostgraduate School,112p. 1~FigureCaptionsFigure1.HapofcentralCalifornia coastshowinggeographic locations andfaultscitedintextandlocationofFigure'2.Figure2.Detailedaeromagnetic mapofcentralCalifornia coastbetweenPointSurandSanSimeon.Flightlines4had1milespacing,flownnormaltothecoast.F-8

~~~~125I21!200Cg+l'..."".0~'00",~:..

~0SonFrancisco' 80~pCaMonterey..

"~Pt.SurX,.o~0OC.00CapeSonMartin~"'.:.:,

SanSimeon'-:.~q~~~O-"~:Oy~P)Figure2,:,SantaPfSot"MarIa:Basin:;:.'.TransverseRongesPl.Argualla"'::.:,~""::.:,,Santa,:,

F-9Pij' 35'30'6uMorihloConlourtnltrvol50nT-2means200nTC'o,'.t>C'g'*H,~r'u)~moo<o1SOgI~Kosorifc"lt020Xmp~IoI~(>wrcun~5QSerrcE>>cccCpc<gyes'0 TheSanGrcgorio-Hns rifaultt(cndparallels thecentralCalifornia coastfromitsinter'ection sviththcSanAn-dreasfaultnorthsvcstofS;mFrancisco tosouthofPointSal(Fig.I).Inthisrcportweprcscnton-landgco!OgiccviJcnccforaboutIISkmofriht-lateral strikesliponthiscomplexfaultzone.On-landandoffsliore segmentsofthefaulttrendarcwelldefinedbygeologicmappingandmarinesurveys(I-I).Conn'ecting linksremaincontroversial, however.whereinferredthroughshallowwaterincoastalzoneswhereacousticprotiling dataarcabsentorambiguous (5-7).Ncverthc-80GUAI.ALABASINKM0BOOEGANEAOPT.REYESless.chancealignment of>>cveralwcll-dclincdni;Ijorfalilts>>cern>>

Iinlikcly.

Fur>>'hcrmore, ifourevidencef'rrightsliponthcfaulttrendisvalid,throughgoing continuity ofthc,faultzoneisrequired.

Thcevidenceforrightslipconsistsofscvcnpairsol'tl'>>et geologicfcl(turcs (Fig>>.Iand2).Yoncofthc>>careindi-viduallyunequivocal.

hutt:(kentogctlier theypresentacompelling argument.

Lineargeologicandpalcogcographic fea-turesformingpiercingpointsont'liultplanesarethemosisensitive indicators ofstrikeslip(S).Certainoftheoil'sctpairslistedbc!oivarclinarfeatures.

butunfortun:itcly nuncaretightlycon-strained.

Conscqucntly, weshowprob-ablcoffsetranges.Thccommondenomi-natorofIISkm(Fig.2)isourestimateof~rightslipontheSanGregorio-Hosgri faulttrend.Detailsot'heoffsetgeologicfeaturesareprescntcd clscsvhcrc (5,6),butinsuminarytheyincludethcI'ollowing.

I)7%e8udega-Gaalala f(n(l(-Pilar-ci(osf(n(l(oJJse(pair(asterisks inFig.I).Ga7(7~10-J t(7.'<II';tttl('l'Itd ATTACRIENT GAbstract.

7%<<Sea(Circ@or(O-II(>.'ll!ri f(nil((r<<n(lIsa('n(po(i('n(

offl(('anvIM(If<<as fa((I(sys(e(nun>a%i<%(l(erenn(l'n(v('>een

<<lnn((ILSIilun(((mrs ofpos(-I'arlv

.hlioeenerigla-la((

r<<ls(rileslip.Ifs<<.rig%(.clipon(I(eSanr'hodr<<as

<<n(lSanGre-gurio-Ilosgri fanl(s<<troan(sforn(os(of(l(eniui'ennva l>e(>veen (I((I'<((ific'ani I>,'or(II An(eric<<a pla(es.sincen(i(I-hliueene (in(<<.Irnr(I(ern(ore.

(IN'M(gnila(le ofrigl((sliponaP((leog('ne pro(a-$<<nAnclreasJin(l(i<<Jc'rrecl fr>nn(I(ipris('n(elis.(riha(ion ofgrani(i<<l>ase(nen(

isr((la('ed

('ansi(l(

ralllyu%enA><<ug(n<<-R<<e(n(

San'regoriu-II<<I g(irigl((.clipis(al'enin(o<<ceunn(.~III>>CIIV>>

liiilllIsiular>:Illuollc(I iulce>>tral>>tr;indoftheS:inAndrca>>faultg9).Althoughlyingsvc>>tofthcinodcrnSanAinlic:is fault.thcI'ilaicito>>

fiultthusi>>thclocal>>tructurd boundaryl>c-tsvccnIranciscan Complexonthenorth-east:indgraniticbasementonthcsouth-wc>>t.Thisprc-SlinGrcgoriof:uiltmaybcnn'scttothenortha>>';inint'err<<d>>truc-turalcontactscpar;iting thcnorth-ernmostgraniticbasementoutcropsatBodegaHeadfromthcFranciscan-floorcd(?)latestCretaceous and'e;irlyTertiaryGualalab;(sinivcstoftheSanAndrcasfault(/0).2)I'O'In(Revessec(ion-Den Lun(on(Ihloan(ain sec(iunoffs<<((x'sinFig.I).Distinctive Tertiarysections, including unconformity-bound p;lcl'ages otI'i(lco-cenc,middleMiocene,andupper5(io-ccnc-Pliocene age.aswellascom-parablegraniticbasement.

occuratPointRcycsandBcnLomondMountain(II-I3).3)PigeonPointFora(a(ion-San(a Lu-ciaCre(ac<<o((s uJlsetpair(A.sinFig.I).UpperCretaceous deep-scafandepositsofthcPigeonPointFormation

(!4,/5)andanassociated Cretaceous basinm;ir-gin(6)areprobablyofl'seifromsimilarfcaturcsintheSantaLuciaRange(6).Inaddition.

preliminary studiessucgestthatOligo-I>liocene shallow-todeep-ma-rinefaciesoverlying thePigeonPointFormation (l6)mayhaveoffsetequiva-.lentsinthcSantaLuciaRange(5).4)OJfse(ufogsl(oreravi(vridge(Fig.I).Silver(17)proposedthatalineargravityfeatureoffshorefromAnoNuevoSFBPlSANPEOROPESCAOERO PIGEONPT.$)FhiAN0NUEvoPT.qBENL'OMOMOATN.Ae(LARCITOS FAULTSALIMIAM/

CCFRANCISCAN~

S0CONTACT~SANSIMEON~Ii>>DDXc>>>>>>>f'(MBA>hr>>5+CL<<'JPT.SAgSt:II'.I(L'll, VOI..IVV.I.lJANUARY1>77>Il35l25IPOINTREYESIBENLOMOMOOFFSET05IIPIGEONPOINTISANTALUCIAOFFSETA>70MUEvo-SUROFFSETtsILVERI((7I-l(5tdcCoolo5ILI-95O115GUAI.*LAPILAACITOSOFFSETKMCOMMONPOI(ITSUR-CAMQRIAOFFsETPARTIALOFFSETOFBIGSURMiOCENEOFFSETSAMSIMEOM-POINTSALOFFSETINALLI80(7CGhIICnOIOOKM200KM300iiKMWI>8EACMI.ATERAIpos!TloNS or-oFFsETMlopolNTS ALONGSANGREGORIO-I.IOSGRIFAULTFig.Ittcf().SI:>(>ufBcutnuiefC:>lu(cs Ull'ic(inarighth>(crit>>CI>iCalongihcsh>nGrc('<>(h>-

II(>iI:(i Ihi>liI(CIKI.Scctealfa>'(liicuii>h>>I.

I(ig.2triuhlhO(l'sctrangeclni(tf>>rSI>KI'col<<l I>il'>>ctI>>.iisih>>>v(IinI>ig..lI>(I>Idi>>c<>c>I inIhctext.(Kl'l(>.t(U75(7KAI(

I1I>(795(>I).5(VII C>>Py>ighi CIV(KhhhBG-1

~~~4PRCSCNTNQRIWRNIIHTtYSALONdiSCNCNT>00KMP'PMIOCENEOLCENEpALEO.Ct(ETACEOuq PACIFICN.AMERICANPLATES(RTNATCRdNDLNRR>ISTS)nOrXOVlnAI)NCNTNCANL~DFSRVNMNQRSCNCNT, FSS>~.hGhLACNCSANAXSRCASleJVCNCNT L<N.SCTOOIw~GOOXw5009400C$~~~~~>~~ill+rPROTOSANANDREASotIMOVEMENTONJIill,SAttANOREASFAULTSANGREGORIOACT>VITYPROTO-SAN ANDREASMOVEMENTIM'X)CONSIDERING SANGREGORIOFA>f~T1000Co1000AGE(MYBP)OTHERFAULTSMOVEMENT(MAX)DISREGARDING POTEtitlAL CUMULATIVE SANGREGCROIrINDISPLACEMENT SANANDNEASSANGREGORIOCONnIIh0>&CRNVwTDrSRLR><ANSRSCNCMTR(STCNSNCOXICSCNAhCRCASd$AN~~ltQVClcCNT

1T'/TTIPOLCTIN>0SANAICACASDTTSC'IILFRQQASLCLI>OT&SCITIANOASC+CNTFig.3(left).NorthernlimitOf'Salinian blockafterrestoration ofNcogcnerightslipontheSanAAdrcasfaultalone(A)oronthcSanAndrcasfaultplustheSanGrcgorio.HOsgri faulttrend(0).Theremaining o(Tsctofgnniticb:iscmcni noiaccoun(ed forbyNeogcaerightslipmaybe0measurenfrightslipon0pro>o-San Andreasf:iu(1.Fig.4(Tight).(CurveA)Time-Of)set curve((2)mndi(lcdtnShowthee(feetofSanCtcgorio-Hi>sgi rightslip.(Curve0)RelativemotionofthePaci(icandNorthAmericanp(ates(33).Seetextfordiscussion.

Pointistheoffsetexpression ofthccon-tactbetweenFranciscan rocksandgra-niticbasementofthe.SalinianblockintheSantaLuciaRange.5)PointSnr~Francisran-Carnhria PinesslabnfJsetpair(underlining inFig.I).TheFr~nciscan subduction complexofthecentralCalifornia coastisgeneral-lyapotassium feldspar-free mctascdi-mentarysequence(IS,-l9).Exceptions tothisgcneraliza(ion arcstructural blocksofpotassium feldspar-bearing graywacke-shale atPointSurandCam-bria(IS,/9).Thesetivoblocks:ipparcnt-IyhavebeenoffsetbySanGregorio-Hosgrirightslip.6)PointSarItliaeene sarttlstone-Frarteisettrt sttnreeterrrtne<>/setpair.hfiocencs:indstonc occupiesusn>nllfitful(sli<<civithintheSurfaultzoneseg-mentofthcSanGrcgorio-flosgri faulttrendne;irPointSur(5,2tI).Dcspi(ctheImn>cifliltc plox>A>ltyolI'.r;lni(ic b>I!icnlcntcxpi>hcdiAhliocct>c (talc(5).(hcs;>Add(one h:lh'tillcxcl>>SILL'ly I'rilllc>si:all provenance (5).Atlc;ih(60ktnofrightslipi>>requiredtoproviilcanadequateI'ranciscaii sourcetcrranc.'I'hcol)'sctcannotcxcccdl05kn>.hoivcvcr, bc-ci>u<cth>>silllds(ot>c I'l.ksvole>it>lc cli>s(stypic;ilofhtioc<<ncsi>>>>(Stot>cs near('>mbri:>

(I).TlicIi>L'killovLI'liip ofLII)hctbc('ivccli IhcIi'I>AtSul'i>oct!Ac

)inifs(L>nc anilotl>crotl'hLIp:iirs(I'ig.2)LILTCSt>O(LIL'lL"it (hcollhCIIll'i',lllni;AI, bcL;iilsc(hi;Miocct>ctai>llifh(oi>L'h lnaIilul(sliceincorporated inthef'aultzoneatanintermediate distance.

7)SanSinteonopltiolite-Point Srtloyltiolite offsetpair(doubleumlerlining inFig.I).Hill(22)reportedtheprobableoffsetofaihfesozoic ophiolitc andanoverlying "Per(fary sequencefromPointSaltothcSanSimeonareaalongtheHosgriscgmcntofthcfaulttrend.Displaccmcnt ofthePointSal-S;mSimeonophiolitc association alongtheHoscriscgmcntoccurred5tol3millionyearsago(22).Otherof)'sctindicators demonstrate post-carly Mioceneandprobablepost-middle Miocenerightslip.Holoccncmovcmcntisdocumented foronlandandoA'shorefaultscgmcnts(2~)Graniticb:iscmcnt of'hcS:ilinian blockwestof(lieSanAndre:isfaultisollsctby>IA>inii>>i>11>

of5lt)kn>.biiscdonnor(hcrnmost graniticcxposurc>>

atBo-deg:>Head(Itig.I).Ifgraniticbaden>cnt extendso(l'shore toI'ointAren:i(2I).thcmaximun>oil'scti>>600km(Itig.3).Rcs-toritionof'vcll.documcntcd post-Iiv-ccncSanAndre;isrightslipol'05kin(24-?6)bringsthc>>orthcrn litnitofS:ili-'i:in b;iscmcnt h:icktopositionAinIrig.3.Tl>cdill'Lrcncc bctivccnpositionA(Itig.3);iniltheno)tl>ivcstliit>itofSicr-rilnlu>Ken>cut h;Isbccnttlkcn;Is;I n>i'.,'I~)dircol'rc-Ioccnc"proto-8:>I>

Aii-ilrc:is".right slip(27.'8).()IlierrLI(ioi>al cviilcncc pk>cch(l>isilcl'orni:>(ion inI';I~lciiccnctitnc(5.29).Iloivcvcr.

thcILVA(o.G-2Irationfailstoconsidertheextension ofSalinianbasementby!15kmofSanGre-gorio-Elosgri rightslipnorthofitsinter-sectionwiththcSanAndreasI'ault(22.p.f293)rThcrestoration ofthisadditional II5kmof'Neogene toRecentrightsliptoposition8(Fig.3)reducesbyone-third orperhapstwo-thirds theapparentright-slipof)setofthenorthernlimitoftheSa-linianblockbythesupposedproto-San Andreasfault.Furthcrmorc.

inthcun-likelyeventthatthelimitofSicrranbase-mentactuallyliestothenotthinthesub-sud;Icc(30),AndifBodcgafleadisnearthenorthernlimitofSaliniangraniticbasement.

thenaproto-San Andreasfaultisprccludcd alongthemodernSanAndre:>spathwayincentralCalifornia.

Inanycvcnt,thcproto-San Andreasfaultapp;ircntly Lvasnotatransform f;iult:in:ilogous tothcmodernSanAn-dre:isI'aiiltsystem.Instc:>d.

proto-San Andre;isf:iulting mayhavebeenthcgeo-logicrcsohttion ofobliquesubduction alongthccentralCaliforni:i coastinciirlyTcr(iarytime((I).Righ(Slipof'hcS;mAndrcasfaultiscoaveAlen(lyiflhpkIycif;I',I;I Iln>L"ills placcn>cnt plotoncurveAinI'ig.0(.'.).Thcilottcdn>1>dili<<;i(ion nl'curveApriorto60Inillionyc:Ir>>agoshoivsthec(l'Lc(ofdisrcg:>riling S;inGreg>irio-I lohgririgl>tSlipinproto-S:>I)

Anilrc:ih f:Iultin-tcrprc(:itious.

CurvellinItig.Ishi>>L>IhcIeh>(lvi:lnovL'AIL'}lt lic(ivccn (lieI,iI'>IllilailHo>(hAnil,>'lean pkl(cs(I)SCII:.NEI:..

Vot..Iv) i~~~iSYithihtheiinccrt:<inty ofIhccurves,(AOStn<OLCIACnt lv<<tLVCCA tlicplatCSl)ASbccnloe:ilircd;ihuig (licS;<nAndic;i>>faultproperI'vrthclait6niillivnyears.Bctsvccnth;it(imc:uulthcc;irlycaIio-ccAc,A<As(oftilepl<it<<Ill<1(ioA wasillstriivu(<<<l bc(LLC<<nthcS;<nAmlrcas:uid SanG<'cgorio-Ilvigri f;iulttrends.Ti<usthcprcscntextcniion ofgraniticbi<ce-mentofthcS;ilinian bio;kinI:irgcpartisexpl'<incd byrightsliponf:iultsofthcNcogencSinAndre:is(nuitiyitem,assuggcstccl hyJohnsonandWorn<<:rk(34).S.A.QRAHA>ctFrplnscsfios<Drparlsnrn(,

11'csternRegion.ChevronU.<.e'L.Inc"a,SanFs'csssciscu.

Cc<1%rssics S)4I/9<<Y.I(..DICKIHso~

DCp<<fin<msOfGC'OIOJLV.

SICSS<fs)rcl Univcfsily, Sf<<<<ford.

California S)43053-d:iyperiodonhnlnsmilk.Never-(~8,pilp!iof<illclgcsLliiplcly fcililcc,'cl

%)%fit;1<NIILipLl<cvcloplncntLvllcli,nursedonI<<sin)milk.lnanattempttodc(ciminc thccaiiscofdc;ith.tissuesectionsfrom.thcaf-fcctcclpopswerccx:imincd histolvgi

~cally.Thinsectionsofskin.lung.liver.stomach.bone.andmusclewercpre-paredfron)((-d;<y-old pup>>nursedonIsnlnsmilk.Thesectionswerest;iinedwi(hhcmatvxylin andcvsinandexaminedundertliclightmicroscope.

Onlythcskinappc;ircd abnnrnial, displaying.

fvcal;iciltcclefill;ltltis, gcllc.'I",ll Ulldcfclcvclop ment.andI'olliclc atrophv.FL<r(hcrmvrc, thcstritumgfanulosum w'issignific;intly thickened andthenumberofhairsh;if(smarl'cdly reduced.Allotherorgansap-pearccfnor<nal.thoughundersized.

andnocvidcnceofinfection, allergy.orin-completedigestion ofmilkwasob-sc<'veil.

Histological observations iverealsomadeofmammaryglandsot'n)losd;imswhosepupswere'close todeath.Ingen-eral,thcscglandsappearedlessactiveandsmallerthan(hoseofnormal8/6mice.Moreover.

weobservedthatIs<<isodamsfrequently yieldlessmilk.Tal'entogether.

thesesymptomsaresimilartothosedescribed byl<IutchandHurley(3)inratpupsnursedondamire.ceivingapostgestational zinc-free dict.Thi>>dictleadstoasopercentdecreaseinthezinccontentofthemilkbydayISoflactation, withonlyminimalctfectsontheotherconstituents.

Asaresult.nurs-ingpupsa'eseverelydepletedofplasmazinc.1Lvo-thirds ofsuchanimalsdiea<Hiallexhibitretardedgrow(han'dseveredermatitis.

Nloreovcr.

totalmilkproduc-tionwasreducedhy50pcrccntinthczinc-dcficicnt dams.Bcc;<L<se ofthesimilarity ofsymptomsbetweenthcdietary-induced zincdcfi-cicncyandthelrflusl<<sill'yndrome, wecomparedthcconcentrations ofzincinthemilkofInihnandnormalmice.AsshowninTableI,thezinccontentofthcmill'l'utant miceisreduced34per-centfromthatofnormalB/6mi<<c.Thisdill'crcncc isscenthrvugliout lactation andisrc(lcctcd inthcwholebodyzincCOnC<<ntratiunS OfS-clay-VI<I SOCklingani-mals.Ilowcver, Lvcfvunilnvsuchdeti-cicncyineitherthephiiniaol'lactating Is<ills<LI,'lillsi Llflntlicc;ifc,'<sacs ot:<<lilt(

Is<siss<fcn<1<lcs.

Sill<.'C><chil(is<siss<Ic:A1<<lci exhibitnorm;ilconccntr;i(iong OI'ot;ilhvdyzinc.it:ippc:<rs (hatthemut:iticiii involvesre<inc<<LI trini(ort o('zincfrompi'<in<<:I<1<liilk.IhcIt.'6d:in<8niaint:ii<1;I 2<ii<<co<ieciitfatlon iuthc<<iilktliatiitcntliilcsh<1',tie<'tlilil thiltislIll<<plilii:li<

right0197>8AAAS1stJ,C.Clack.disc<<<<a<ion.

Stanfoidt<nivccvi<y (1966).I),C.Rove.U.S.Grul.Sun..I'rc>f.I'cip.698(1972).I,C,Cro>>c)l.Grul.Sac;Am,Bull.68,993(1957)~U.R,Lowe,Ivoc.24<hIns.Crnl.Caner.6.7S(1972).J.C.C)acka<adF..E.Rcahh,C<rlif.Div..<(Ines Grcil.Sprr.I'cp.,inprese.E.A.Silver.(irc>I.Sc>e.Ani.Ahssr.P<c>gsccrn c6,253(1974).W,Giihcc<.Ca'<il.Sor.An<.Bull.84,33)7I)973)..J.)(su,C<r!i%Dias.LtfnrsCrul.Sprr.Rcp.JS(1969).P.D.Track.Bus(.Drp.Groi.Uni'.Culif.)3.)33(1926)C,A.Hall.Jr..U.S.<7ruf.Srrcv..<fisc.

FieldSr<cd.,<fup

.LII'L'9((974).,Srirnc'r198.)29(()975).F.A,Silver.J.R.Cue<ay.A.K.Ca>per.inG(,girGuiIrs<IIvnrshrnCora<Rarer..PainsRrycsRrgsi>n.Crrir)i>micr.

J.Il.I.ipps;ind F,.h(.h)oores.Fdc.(Geological Sa>eic<)i Savca-men<o.Calif,.19~I),vo(.I.pp.IIi<.W.R.Uickincon.

D.S.Cowan,R.A.S<<h>>cick-cc<.Anr.Ass<>'.Pc's.(ri.Bn<S.So.3c(l91kV.h(a<<hews.

I(t.i)ii,f.60.2128(1916).T.H.Hi)scnandh(.)I.Link.inI'ir<c<ieriir Svuipusiun<.

D.W.Lvcaver.G.)In<no>lay.

• .Ti(><a>n, Eds.(Soie<yofEconomicPa<<<on<o)-

ogas<sandhtincca)aig<c<s.

Tulsa.)9151.p.367.J.Suppe.Crul.S<>aiAcn.Bull.Sl,3253(I'9<0).R.W.Kic<)cr.Z.F..pe<<<<man, D.C.Ro>>.D.Go<<fcicd,SsanfurdUma.Pabl.Grot.Sci.S.339((973).Forcsamp(e.sccS.A.Graham.Iv'ra<<mrSvrn-posiuni.*.

E.Fri<vche.

H.TccBes<.Jr..W.LV.Wocn:<cd<

~Eds.<So<<ia<yofEconomicPal<<un-co)ogii<s and~1(nccatogis<s.

Tu)sa.1976).p.125.Secihcdu<<cdlincinFig.3.P.J.Coney.Grus.Sor.Am.Sprr.Pup..incecce,IodificdfromchccucvesofDiekinconrc al.124)andHclvenandLink<26)inac<<ocd.ance wi<)iahtiocencPliocneboundarynear5millionye.icvago.(rocade<ail<<ddiv<<ussion sccGraham<5<.T.A<wa<crandP.81o<nar.Ss<<nlurdUniv.,Pub(.

Grus,Sri.13.136(1973).I,D.Johnsonan3LV.<Ho<mack.

Grolngy2.II((914).OurccveacehwassupponedinpartbytheEarthScienceSec<ion.NationalScienceFounda<ion (gian<UES1=01728).

htay1977;revised22Augusi19771617v021231516References and!Co<es

'>728I.A.K.Cooper.U.S.Crul.Su<v.OprnFilrRrp.I901((973).p.65.2.G.E.'Wchec.Geol.Soc.Am.Ahssr.Programs9.524(1977).3.H.G.Gccne.LV.H.Lee.D.S.8(cculioC.

E.E.Bmhb.U.S.GrnLSun..'<fisc.

FieldScud.hfnp<IF;<I811973)4.H.C.LVagncr.U.S.Grol.SrrniOpenFilrRrp.(1974).S:S.*.Ciiaham.diss<<<<a<ion.

S<anfocdUnivccsi<y (1976),'p.

5)0.6.andW.R.Dickincon.

CalifDiv..ifinrs Gros.Si>rr.Rrp.,inpccss.7.E.A.Silver.Gaul.Snc'.Ain.Ah<sr.Progranis 9,500(1917).8.J.C.Cro>>eil.Gros.Soc.An.Sprr.Pnp.ll(196).p.61.9.forecamp(e.secT.H:Ni(venandT.R.Simon(.Jr.,J.Rcs.U.S.Grnl.$<<n.l.439<)913).(0.C.ht.LVcm>>ocih.

Ssunfi>icl Univ.Pabs.Geol.Srf.I(.(30()968).1(.A.J.Galloway, Calif.Div..<finrs GroLBull.202((977).19303132333523ZincDeficiency ini<<furine IXIilkUndcrIics Expression oftheLeIIIal(7<1'ilI'IIII) iver((t:((ion Arcccssivc mutation.

designated le-(lailnsill'lns).

Lv:<8diicovcrcd a<nongniigcofthcCS"sIIL'6J (l)I6)striin(I).Pupsnuriedoni<<iliad:iin>>exhibitstunt-cLIgroi'vill,;<elite

<le<'ill;lli'Ils, alopcci;1

~andLlc:ithpriortoLvcanin.

SincenormalBI6pupi(I.nsl.ns) dicrvhcnnuricdonIn<losinilk,(lieclcfcctrciial<<iin(hcmilk.Ilvlcoic<',

linln<pi<psdcvclc'>p tlol'<ll;illy iffiiitCr-nuriC<l Vn;iAO<in:ilClam.(.>C-nctic'in:ilyici inalic;ite tliatlnsiiloc:i(cdVllL'hi'La<llviO<11<<

(<lidilll(si),6\:el<(inlol'I'ini lio>>1(lic;igooti hs)loci<i.IllccllcctsLa(lssslsssI<Ill(iclll1<a)who<ii pupspcriiitatAIIi(agesoflactation (2).a<Ye,h;<vcevnfircncd tlmtncvvborns fv>>-tcrcclonlnslnsdan<8'itmid-lact;itinn orI;i(chie(:<(ion;irc ais<<vc<'c'.IV

<itl'a.'cled iis(I<useAll<'i<<LI (fL'<1<1(liebeg<An<A<:

ofI;<c(illion,In;<clclition, Lvchavefoun<I;1Llif-fcfcACCilihusccp1<l'ail<tv tvthcc(lectsvflnslsn<<<ilkcvithrcip<<cttvthc<)'.cOI'i<pi.>i(owl<of<i pl<ps;<lc.'f<'cvcfillsly co<An<i(teil toif<<1<th:1('Icf 3d;<yionIn<losA<ilk.cvciiwh<<iisiihscquvntly tfani-(L<<cclI<<:iiio<<>>:il.I'cni.()hlerpiipi,ontli<<otlici li;iiul,Ii;iviiig niiric<loiiin<i<n;ilniill('r,uiccvd.iys,I'<irqucntly h<<rviVC:<0<)3(>g<<)ss7<LS) l)Juu<(s<>a<.5<L'0

(:opySCII!h<CIL YUI..IV'S,IJJA'St<A)tv

)><78Abstmct.Tlsrinahilisy c>fnursingpopsIosorvivransssiII'fnss'ccI<os<so-i'gosss forIherc'ccrrivr'nuslali<<n.

Icthilmilk(Im).isccsrrrlalrd i<<illsarrclocfian in-issclevelsofboll<ss<ilI'ncl popcarcass.rlcln<inislrasiou of-ini'spnpsssssrsing onImlm.cl<<nss rrdssccsIln'lisrrvc'cl snorsalily

<<nclssusrbsclilv.

IIissaggc'sfrcl lhnlIm<<l(crs-inclransporl freonnsafcrsusll>lci<icl scssssilI;<<nclslscssii.rssssclynusy proviclc'srfssl infarnsa-clionforunclrrssanding slsc'are'susnass disease,cscrridcrn<afisis rnlcropashic'<<.

G-3

~y~,

4~Roprinlcd from'6Docombor1975,Volumo190,pp.1l294SanSimeon-Hosgri FaultSyhten),CoastalCalifornia:

EconomicandEnvironmental Implications TheSanSimeonfaultterminates theArroyodclOsofault,whichcutsthroughthelowerpartofthc12-mterrace(l.4).ThcPl<<istocenc terracedepositswithintheregionarc130,000>30,000and140.000+20,000yearsotd(5);therefore thcAr-royodelOsofaultisyoungerthanapprox-imately130,000yearsand,atleastinpart,thcSanSimeonfaultmustbes(illyounger.Anepicenter (dateunrceordcd) islocatedontheArroyodclOsofaultandthcmag-nitudeoftheearthquake isreportedtohavebeenbctwcen4.0and4.4(6).Holden(7)reportsearthquakes of26Octoberor26November1852andIFebruary1853atSanSimeon,where"houseswereinjured.n However,theauthenticity ol'heseearlyAbstract.

Therehasbeen80l'ilomerrrs orntoreofrightslipalongthelateI7unIernary SanSimeon-llosgri faulIsysremofcaasralCalifornia during"thelast5Io13millionyears.Parrofanoil-richbasinisProbablyogser bythisfnulIsystem,andIht'sysrcm maybeapotential ha:ardIonearbyslrucrures.

Comparison ofstratigraphic sectionsex-posedonoppositesidesofthclateQuater-narySanSimeon-llosgri faultsystematPointSalandnearSanSimeon(Fig.1)stronglysuggestslarge-scale lateraldis-placement.

Thcnatureandagcol'trikc-slipdisplacement alongthefaultsystemhasimportant economicandenvironmen-talimplications, foritsuggeststhepossiblelocationofanofTshorcextension oftheoil-producing SantaMariabasinandindicates thatthcsystemposesupotential hazardtocngincered facilities.

ThcSanSimeonfaultincoastalcentral'alifornia, firstnamedin1974(I),canbetracedonlandforadistanceofapproxi-mately19km-thatis,'romRaggedPointtoSanSimeonPoint(Fig.2).lntheareaoffshorefromRaggedPoint,HoskinsandGriAiths(2)showa65-kmnorthwestward extension ofthcSanSimeonfault.Silver(3)reportsafaultwithasmuchas5kmofdipseparation intheolTshorebasinsouthofPointSur(thatis.80kmnorthofSanSimeon),whi<<hmaybcthcnorthernexten-sionofthcSanSimeonfault.TheSanSimeonfaultmayalsoextendfarthersouthfromSanSimeonPointtonearPointEstcro(Fig.I)inthcutTshore, aspostulated byothers(l).Suchasuggestion issupported bythefactthatthecoastline isstraightandrisesabruptlyfromthesea.NearSanSimeonPointthetraceofthcSanSim<<onfaultisconcealed bylatePleistoecnc orHoloceneslightlycementeddunesandd<<posits.

ltfaultsthe122-mPlcistoeenc terraceapproximately 5kmnortheast ofPointPi<<tlrasSlaneas,butdocsnoteutthe12-mterra<<<<near eitherSrcaker1'ointorRagged1'oint.TheArroyoLagunafault(Fig.2)isbe-lievedtobearelatively

>oungerandmorcrecentlyactivestrandol'heSanSimeonfaultzone.Thisfaultism:irk<<Jbyapro-noun<<edlin<<arvalleynorthofSanSim<<onPoint(4),hya75-mfaults<<arp,andbyfaultingofthe122-mPleistocene t<<rracc.Thefaultcrossess<<v<<ralwest-orsouth-west.draining canyons,including Arro>ollondu.ArroyodclusChinos.andthreeotherunnamedcanyonsbetweenArroyodclosChinosandArroyodclaCruz(4).Eachcanyonismarkedbyrightlateralde-viationof150to450m:however.thefaultdoesnotjuxtapose markedlydilTercnt rocksequences ortypes(Fig.2)asdocstheSanSimeonfault.'.~coCoooSooMofloIo+ROSSOOPtooVROCOOITZPl&44ooBloncooI>>B4II~~oo54ooooSooSnoOOIIPIPoloRootoo0eoCOolnooILov,poopoQPlfOI~IoChXoTIlOOvMonoBogrollaPlSooLIoooClY,tVrovoooCgoo/C)caXnOIOBroncoOrvhot;OIOI0lOoIIlooPonoonoPlLonoocPlAIOOOOOPtConcooloo>>>>

MooLOCOInoI1BioI'ig.I.Locationul'ihcSunSilo<<unIlutgrifaultsystem.I)usemupicfrnuiJenningsIII)unJseveraluthersources(I.Z.4.u.IO.13).inputsinJit~tchypuhyxsllplugsoftheblurlaItu<<k-IslayIlillturn.plex(I,IO,I7).

earthquake reportshasbeenqucsti(8).ThcSanSimeonfaulttcrminatcs thcO<<cani<<IVcst lluasna-Suey faultsystem(Fig.I).TheIVcstlluasnafaultmaytcr-.ntinatcthc)idnafault(9).whichinturndispla<<cs I'Icistoc<<nc antilateI'I<<istoccnc deposits(9).Thus,althoughmov<<mentbe-gancarlicr,probablybctvvccnthclateMioccn<<and latePlio<<cnc, th<<SanSim-eonIaultmustbePlcistoccnc oryounger.andstrandsorassocitt<<dfaultsmaybcevenyounger.ThcHosgrifault(l0),alsocalledthcEastBoumlaryfaultorfaultzone(I),ex-tendssoutheastward fromnearPointPiedrasBlancastonearPointSal,butsouthofPointSalthccontinuation isnotclear(II).Seismicreliection records(I,l0)showthattherehasbeendipsepara-tion,withthcwestsidemovingdownrcla-tivctothccastside.Di}Tercntial movcmcnt'hasoc<<urrcdintermittently alongthcHos-grifaultfromlateMiocenetoHolocenetime(I).Earthquake cpicenters alongthe~ssThcrocksinthcI'ointSalareahaveccnd<<scrih<<d ItyIVoodring andllram-'as h<<cnd<<scribed hyIlopson<<ral.(I5).Thcold<<strocksinthatar<<aarcthoseoftheJurassic(~l60milliony<<ars)ophiolit<<,

whichconsistsofalowerpartofs<<rp<<ntin-itc.layer<<dultramalic ro<<ks.andgabbro:andanupp<<rpartofdiorit<<.quartzdiorite,adikeandsillcomplex,andsubmarine pil-lowlavas.Greenish-gray tulTa<<<<ous radio-larianchert,overlainbyJurassicshaleandsandstone.

r<<stsonthcophiolitc complex(I5).Asimilarsequ<<n<<cofrocksoccursnorthol'S;mSimeon(I'ig.2)betweentheArroyodclOsoandSanSim<<onIaults,butthclowerpartofthccomplexprcscntnearPointSalisappar<<ntly ahs<<nt,asarcthcsubmarine lavas.inthcSanSimeonarea.AJurassicophiolitc castof'Ivlorro Bay(13.16).castoftheSanSimeonfault,andinrelatively closeproximity toSanSim-eon,isoverlainbyrcdradiolarian chert,notthcdistinctive greenish-gray tu(Taccous chertwestol'theSanSimeonfault.ThcFranciscan shale(Fig.2)intheSanfaultsuggesttllatltcouldhcsclsnllcall~

active(I,IO,l2).Arpuntcnts supportin~

amlrefutingth<<possiltility ofstrike-slip lcttc(/4)and.morcrc<<<<ntly, tileopltiniitc

'novcmcnt alongthcllosgriIaulthavebeencaret'ully r<<viewed(I);how<<vcr,newdatapresent<<d hercstronglysuggestthatthcSanSitnconand}losgrifaultsarcpartofthcsamesyst<<m,rightslipaccounting forthcdistribution ol'urassic toPlio<<<<ncrocks.RecentgeologicmappingnearSanSim-eon(4)andthcareab<<twccnSantaMariaandSnnSimeon(9.I3)(I'igts.Iand2)hasshownthatremarkable similarities existbctw<<enrockswestol'heSanSim<<onfaultzone,nc:trSanSimeon,.and castofthcIlosgrifaultnearPointSal(Fig.I).Ju-rassicophioliti:,

ovcrhtinsuccessively bytulTaccous radiolarian

<<h<<rtandJurassicshale:Oligoccnc nonmarine conglom<<rate, associated tutf,anddistinctive landslide deposits:

andlaterTertiarychertyshaleol'imilar composition andhistories ar<<oIT-sct(Fig.3).Thehorizontal slipcomponent maybcSOkmormore.SueS~NAIXPLA~rsELstoogeI.'lie'e"",QsLosOOtuuSesseeIosse~tsTII'e',eeoseeetssspe5OsTos',PeeeSolresOWsOovota~eo<sssosws TIONCQOseteROOee~ssLosoovoodoo>>so tooPISO>>OeRI~CIsesles~ss01~Oe>>RsolCOISso Cesssesee dodo+ee"oeoUeoLee~IwOeosettOtCaROO.loadsStsotI\Issl RseeelesItoCeesoetO~Sate.avl.t'eeee

/esseseeeoesese SooSeeeossPoeseISIISFig.2.Prc.Quaternary gcotocicmupshnwincdistribution undstratigraphic relations oftheJurassicophiulitc, chert,uralsbutcscqucnw.:

thcOligocene l.o>>pcI'ormatiorn undltluntcrcy ShalenearSanSimeon,California t4).ThismupshouldbccomparedwithgeologicmapsofthcPointSut-t.iouscudurea(/4,IS),wherethcLuspcFormation ovcrlicstheJurassicophiolitc uudshale.Theru<<ksinthcSunSimcun}tointureawouldhavebeenutleastl2kntotfshorcfromPointSulpriortomovc-mcntalongthcSunSimeon-}losgrifaultsystem.Simeonareaconsistsof'darkgreenish-gray andbrosvnweathering clayshale.Theunitislithologically similartothcl.londaFor-mationol'ibblec (IT)southofPointSal,butitisnotrecognized intheSantaMariaarea;itispresumedtolievvithinthefaultblocknortheast oftheSanSimeonfault.JurassicshaleintheSanSimeonareaislithologically similartotheKnoxville For-mation(14)intheSantaMariaareaandtheEspadaFormation ofDibbl<<e(/7)far-thersouth.InboththePointSalandSanSimeonareasthcJurassicshalecontainsbedsofconglomerate consisting ofwcll-rounded,smooth,small.blackchertpeb-bles.Stratigraphically abovetheJurassicophiolitc-chert-shale sequ<<nccinboththeSanSimeonandPointSalareasistheLospeFormation (Fi>>.2),anonmarine rockunitconsisting chiellyofreddishcon-glomerat<<and coarse-grained sandstone andtuIToverlainbygrc<<nishsandstone andtulT(l4).InthePointSalareatheLospcFormation (/4.I5)ofOligoccnc agcoverlapsJurassicshaleandr<<stsonthcophiolitc complex.InthcSanSimeonareasimilarstratigraphic relationships arecomplicat<<d byfaulting(Fig.2).Thcgreenishsaridstone isnotwelldeveloped nearSanSimeon.InboththePointSalandSanSitn<<onareasthc<<onglomerate isunsorted<<ndpoorlystratified. Clastsrangeinsizefromafcwinchestoseveralfeetindiatnctcr andconsistofrocksfromtheophiolitc <<ompl<<xandl<<sscramountsofJurassicchertandshale.NovvhcrcintheH-2 LospcI'ormation westofthcSanSin<<<onfault(Fig.2)arcth<<rcclastsol'da<<itc fclsitcfromthc22-million-to26-millio<I-year-oldMorroRock-Islay flillcomplex(9,13.18),thedacitcol'Ro<<kyButte(T1inFig.I),orthcCamhriaI'clsitc(9.le')).Da-citcandf<<!sit<<clasts arenotpr<<sentinthcLosp<<Formation inthcI'ointSalr<<gion.flowcvcr, clastsoftheserocksar<<pr<<sent intheLospeandOligocene andlowerMiocenerocksonlyafcwkilometers eastofSanSimeon(9)andnearCambria.Thus,theinference ismadethatLospc~stratawestofthcS:mSimeonfaultzonewercnotintheCambriaareaatthcti<neoftheirdeposition. Clastsol'dacitc andCam-briaFclsitearcpresentonlyinPleistocene andyoungerdepositsivestoftheSanSim-eonfault(4).TherearevolcanicashortuffdepositswithinthcLospeFormation atboththcPointSalandSanSiineonlocalities. AtPointSalthetulToccursnearthebaseofthcconglomerate andnearthemiddleofthcLospeFormation (14);northol'anSimeonitoccursaboveconglomcratc. SouthofPointSal,nearLionsHead.alandslide occurswithintheLospcForma-tionbcloivaprominent whitetutTb<.d(14).SouthofBreakerPoint(Fig.2)alargeOligocene hndslidcoralluvialfanalsoliesimmediately beloivtuffandothervolcanicrocksivithintheLospc'Formation. flereclastsintheLospclandslide aremorevari-ableinsizeandlithology thanthoseinthcLospelandslide southol'ointSal:how-cvcr,atbothlocalities theclastsarcpre-dominantly scrpcntinite, cabbro.diorite,andbasalticrocks.Thcoccurrence ofdis-tinctivelandslides orlandslide. likedepos-itsimmediately belowatull'edinthesameform'ation attwowidelyseparated localities onoppositesidesofthcSanSim-eon-Hoscri faultsystemstronglyarguesfortheirpreslipcontiguity. Inadditiontothcr<<markabl<<sim-ihriticsbetweenrocktypes,structural styles.andstratigraphic relationships ofthcdioriteanddikeandsillcomplexwithinthcophiolitc andtothcpresenceofthcLospcFormation nearPointSalandSanSimeon,ther<>anextraordinary resem-blanceb<<tiveenth<<lithologics ofthcmiddleorupperpartofthcMontereyShaleatthesetivoareas.Inbothr<<ionsandeastandwestoftheSanSimeonI'iiultthereisthin-h<<ddcd chertysliatc-achar-acteristic ofthciblontcfcy Slialc.Ilowcvcr,westofthcSanSimeonfault.approxi-matelykmnorthivcst ot'anSim<<onP(int(I'ig.2).0.3-toI-m-<hi'kII.ol'l:Ick<<h<<rtintcrh<<ild<<d ivithdiatonia<<coUs siltsto<ic <Ifc<<IsoI)resent. SI)U<hofI'$)intSal,n<<arI.ionsllcail,id<<ntical lithologics occur(14).III)wcvcf. Intl<$.'sever;II hi<nFig.3.Pfe.Quaternary com-positestratigraphic sectionsofrocksinthePointSal-Lions lleadarea,SantaBarbaraCounty(14.15).andtheSanSimeonPoint-Ragged Pointa<ca.SanLui>>ObispoCounty(4).PointSt)lLiondVCoo~t<og~uooosJsh~~a~c>>tC0dotaidIOducatOhdOosaeoIOiieoehotel'NII<lottet<Coetotdroeooteoh< <<4llleeti rteeeoiah deoOOStroche5$<<OeOIOOLoiot4hotohfeohrIIIOOtoilIJttoiietIlottJotaSIKihtelOthettdtSonSimeonPointRot)<<et<PointTm+'hoehJIVIden~J,oo.eie.,s' LQo0$C),lcJ<<6)CJ<'CeJsti~++JereC2datohdIurd<oeittahdulttaehaha eOCIIIfthcconclusion iscorrect.thenth<<rcareatleastthreesignilicant corollaries. I)Thcrateol'motion b<<tweenthePa<<if-icandNorthAmericanplates.between4.5andIOmillionyearsago.averaged4.5cm/yearaccordinc toAtivaterand%(ulnar(20).Therefore, 450kmofdisplac<<ment wouldhavetakenplacewithinthelastIOmilliony<<ars.Thiscal<<ulated amountex-ceedsrightslipm<<asurcdalongthcSanAndreasfaultby150km(21)duringthelastIOtol2millionyears.Sonicofth<<rel-ativemotion.80'kmin5millionto13mil-lionyears,mayhaveb<<cntakenupor;ib-sorbcdintheSaliniablockor-assuc-gcstedhere-olTshorealongthcSanSim-eon-Hosgri faultsystem.2)TheSantaMariabasincontainssev-eralproducing oilfields(/9).Athickness of300mto4kmofCenozoicsedimentary rocksispresentoffshoreI'romtheSanSimeonarea(1-3)andwouldbcpartoftheSantaIh1ariabasinthathasbeendisplIcednorthward alongtheSanSim<<on-Ilosgri faultsystem.Insteadofsimplew<<stwardprojection ol'thatpartoftheSantaMariabasin,ivhichiscurrently produ<<inc <<om-mcrcialquantities ol'hydrocarbons. Un80-kmnorthwest projection mightbcmorcvalid.3)ThclateQuaternary SanSim<<on-Hosgrifaultsystemcouldbcapot<<niial hiiz.irdtoany<<ngin<<cr<<d stru<<tur<< lo<<:i<cdalongthccoastI'romSanSimt.'l)n soUtlitt)thevi<<inityofPurisimaPoint(I'ig.I).C.A.H*t.<.JR.Drpartrr<cr<t ofCieoir)gy. University ofCalijirrnirr. I.osrlngel<st)N)24ttcfcitncch and.'hutch t.EarthSsicnicA$ioci:Itch <PaloA<to.<'Ii<i<'.h -(ic-olugyofIhc$In<harn(o,iiiitul<'c\Iiui<thc<lii-<itinlltg ii<iiililte inil'Ilini'n<.'Ii nl.lrrlnIii(.IIII~i<Ill.l,III<<I$ficctaIrile<cliceIiiIncI'I'it<it}'i In<Iic'IISIIII<Iof<heSant,uthRiinfcaniltii<ctotia$.-re<hit<IorPaci<i<<(eah antiI'<I~<tie('omp.in$ iiiciIahli.h ihi~<cnuaiSirhciintisacnini<ha<iouhia<fr<<t)iahl.i(.al$)'tillfdili'<intr toucrt'I.ill<<I'INI.Z.tt(i.<tuiLuihanilJ.It.<iri<<iihq e<ett.C<iioi.l'rr.(Irol.htrett.<S.3<$tte)11)dredsquarekilometers thathavebeenmappedcastoftheSanSimeonfaultandnorthwest ol'antaMafia(9,13)thickblackchertbedsarenotpresent.AsmalloutcropprobablyofPlioceneagchasbeenmappednearSanSimeon(Fig.2)withintheSanSimeonfaultzone.Thcoutcropcontainsmarinefossil>>:Den-drastcrspicbryozoa.Den<alias< spicSolensp..andNuculana1Saccella) tapi<ria(Dull.f897).Thefossilsdonotdatetherocksmoreprecisely thanearlyPliocenetoHolocene. Thelitholocy. hoivever. issim-ilartothatoftheGraciosaCoarsc-GrainedMemberoftheCureagaSand-stoneinthcSantalvlariaarea(14).Onthewhole,strongstratigraphic andlithologic similarities existbetweentwopackagesoffiveorsixlithologic unitsex-posedintheSanSimeonandPointSalareas.Thcdiameters ofthcscrelatively uniquelithologic packagt.s arcestimated atnotmorcthan20kmeach(4,9.13-15,19).Rocksequences withinaradiusof20toIOOkmtotheeastofSanSimeonareunlikethosewestol'theSanSimeonI'cult.Comparison ofthestratigraphic andlithologic histories oftheareasnearPointSalandSanSim<<on(Fig.I),ar<<asthatliconoppositesidesoftheSanSimeon-Hos-grifaultsystem,indicates stronccvidcnccforrightslipof80ormorckilomctcrs alongthcfaultsystemsincethclateMio-ccncorcaflyPlio<<<<f<c. Itisiissunlcd thats<<paration isequaltoornearly<<qualtothchorizontal slipcompon<<nt. Th>>un-<<ertainti<<s ofd<<termining th<<niinimum horizontal slipcompon<<nt ar<<equaltotheunccrtainti<<s. inoncdir<<<<tion. ol'h<<maxiniumsizeol'hcar<<aofthcstrati-graphicpackag<<s. Thus.tli<<liorizontal slipco<nponcnt is<<ailculatcd tohc80k<normorc(tliatis.Uior<<thanIOOkinh<<tween'I'ointSalandSanSin<<<onI'oint,minusthccstimat<<d maxiiuuin 20-LIIIdia<n<<t<<r ofthcareaol'h<<str;itigraphi<<p;Ickiigcs atS:inSiin<<on;ind I',ointSal).H-3 67IOl2.13E.A.Silver.Sa~uinGrrrl.Srrr.ShortCrnrrsr(l974)p.6IC.A.Ii;rllJr..GeologicmapofthcIricdtasElan<<as-San Simeonregion.Califutma. inptcpr~ration.II.II.VcebandJ.W.Valentine. Grul,Sur'.rlnt.Bull,78.547(l9/rg).CaN/.Drp.It'atrrKrruur.Bull.Iid2(1964).E.S.Iloldcn.Srrrithson. Jlisr.Cullrrt./087(I897).P.Squibb.personalcommunication. hlr.Squibhispataps+identufthcSanLuisObispoCountyi(is.totica(Society. C.A.IlailJr..Grul.Srrc.vlnr.Bull.7)L559(l967):CoNf.Div.,tllnrs Grrrl.,tfup Shrrt(l973);U..S;Grol.Surv.3/irr.FirldSturl..t/up.tlF.!II(I')73):US.Urrrl.Surv..tffrra FirldStrrd.Jlapt/F.!Ou(1974):D.L.Tutncr.Grrrl.Sr>c;Anr.Sprr.Pup.l24(l970).p.9I:D.L.Turner.R.C.Sutdam.C.A.Ilail.Grol.Sur.Am.rtbrtr.Curdillrrun Srrt.2.I!5(1970).II.C.tVagner.US.Grol.Surv.OprnFilrRrp.74-2!2(1974).C.W.Jennings. Col%Div.3/inrsGrul.Prrlirn.Rrp.IJ(I973).W.Gawthtop. U.S.Graf.Surv.OprnFilrKrp.7$-IJs(I975IC.A.IlailJr.."GcrrIoki<<map ofthcCayucos-SanLuivObisporegion,'Z.Grol.Surv..rtfisr.FirtdS/ud..tlap. inpress.l4.tV,P.Nrrrrrdt(ng and~Itwmlctte. U9.Grul.Surv.I'mf.Pup.222(~IS.C.*.Ilupvmr.C.J.I:ro,L'.A.I'es<<rgno. Jr..J.M.Matttnwn. -I'tcliminary rc/Nrrtandgerrirreic uidetothcJur;rvsic ophiolitc nearPoint.'(al.'outhctnCalifornia <<uast."Grul.Sar.:Iw.Car-dillrrunSrrt.Guldrb.Firld7ripPlu.!(MarchI975).l6.B,hl.Page.Grul.Sar.Anr.Bull.gl.957(I972).(7.T.W.DibhlccJr..Calif.Div..tfinrs Bull.I!0(I950).Ig,W.Cr.ErnstandC.A.IlailJr..Grul.Sor.Anr.Bull.8<.523(1974).l9,PacrficSectipn.AmericanAsso<<iation ofPetro-leumGcologivts, Currrlatinn ScanionacrossSanta.')/ariaBurinI:(l959k20.T.AtrratcrandP.hlolnar.StanfordUniv.Pub/.IJ(l973).p.I36.2I.O.F.Ilulfman. Geol.So>>.rtnr.Bull.83.29(3(I972).22.Public>>ation approvedbythedirector. U.S.Geolog-icalSurvey.IthankW.G.Iitnst.G.Octtcl.E.Pampeyan. andII.Wagnerfortherrcrrnstru<<tive comments. J.GucntherandV.Jonesdraftedthcfigures.Researchsupported bvthcU.S.Gcologi~calSurvey.the(qu<<learRcguLnury Commission. andth>>University ofCalifornia Rcscar<<hCom-mittee,29Augustl975:rcviscdl4Octoberl975Copyriyht831/J78 bptheAme)scanAssociation fortheAdvancement ofScienceH-4 J.iiLInpress,tobeublishedin"SanGregorio-HosgriFaultZ,California," editedbyE.A,.SilveroW.R.Hewmark,Calif.Div.ofMinescxGeology,SoecialRessort137.ORXGINANDDEVELOPMENT OFTHELOfPOC-SANTA lARIAPULL-APART BASXNANDITSRELATIONTOTElESANSIMEON-HOSGRX STRIKE-SLIP FAULT,WESTERNCALXFORNXA .Clarence A.Elall,Jr.Department ofEarthandSpaceSciencesUniversity ofCalifornia ~LosAngeles,California 90024ABSTRACTC~Amodelisproposedtoaccountforthedistribution ofCretaceous andEocene.sedimentary rocks,anddistinctive Tertiaryigneous,sedimentary, andvolcaniclasticrocks'that liewithintheWesternTransverse RangesandtheSantaMaria-Lompocregion,SantaBarbaraCounty,California. Comparisons oflithologies andstratigraphic sectionstendtosupportthehypothesis thattheTertiarySantdMaria-Lompoc basinisapull-apart structure thatbegantoformabout14m.y.ago.Following deposition ofthelateTertiarysediments, thewesternpartofthebasinwasdisplaced, sincethePliocene, nearly80to95kmtothenorthwest alongtheSanSimeon-Hosgri fault'one.. INTRODUCTION Aspeculative modelisproposedtoaccountforthedistribution ofTertiaryigneous,sedimentary, andvolcaniclastic rocksthatliewithintheSantaMaria-Lompocregion,SantaBarbaraCounty,California. Geologicmapping,analysesofcoreholes.andwelldata(Hall,1977),andpreliminary fieldinvestigations southeast ofSantaMaria,California suggestthepresenceoftheSantaMariaRiverfault(Fig.1)andthattheSantaMaria-River-Foxen Canyon-Little Pinefaultzone.(Fig.1)mayextendmorethan100kmtothesoutheast. Workonthifaultzonehasbroughttolightsomeprovoca-tivegeologicrelationships whichprovidesupportforseveralstructural models forthedevelopment ofTertiarymarinebasinsalongthecoastofCalifornia andrelatively recentmovementonamajorfaultsystemintheregion.Inaddition, thisworksuggest's thepresenceoftheinferredLompoc-Solvang fault,whichinlargemeasureappearstorepresent thenorthwestern structural marginoftheTransverse Ranges.STRATIGRAPHY Immediately northeast ofthe'antaMariaRiverfault(Hall,1977;andFig.1),i.e.,within3'to4kmofthefault,thefollowing MesozoicandTertiaryrockunitsarepresent:(1)Franciscan melange(thickness unknown), (2)UnnamedCretaceous rocks(morethan457.m),(3)Sespe-Lospe formations (152m),(4)Vaqueros-Rincon formations (304m),'5)ObispoFormation (335-.609 m),(6)PointSalorLowerMontereyFormation (304m),and(7)MontereyFormation (1066m)(Table1).TheSespe-Lospe formations arenotknowntobepresentwithin3to4imsouthwest oftheSantaMariaRiverfault.Southwest oftheSantaMariaR'verfault,i.e.,withinadistanceof9.7kmofthefault,orinthecaseoftheSespe-Lospe, morethan4kmfromthefault,thefollowing rockunitsarepresent:(1)Franciscan melange(thickness unknown), (2)Sespe-Lospe formations (609m),(3)PointSalFormation (228m),(4)MontereyFormation (629m),(5)SisquocFormation (498m),(6)FoxenMudstone(88m),.(7)CareagaSandstone (43m)(Woodring andBramlette, 1950;andFig.2).Althoughthestratigraphy northeast andsouthwest oftheSantaMariaRiverfaultismarkedlydifferent, i.e.,Cretaceous rocks,VaquerosSandstone, andiHnconShale,andinpartSespe-Lospe areabsentintheSantaMariaValleyarea,themostsignificant difference istheabsenceofbetween335mand610mofvolcanicrocks,including volcanicash(ObispoFormation) withinadistanceof35to40kmsouthwest ofthefault,butthepresenceoftheTranquillon volcaniclastic rocks,ofthesameageastheObispoFoxmation, onthesouthwest marginofthebasinmorethan35kmtothesouth(Fig.1).TERTIARY BASINHISTORYAtleastthreemodelscanbeproposedtoaccountfortheabsenceofrockunitswithdistinctive lithologies, namely,theVaqueros, Rincon,andObispoilformations southwest oftheSantaMariaRiverfault:(1)strike-slip movementoftensofkilometers alongthefaultbringingintojuxtaposition markedlydif-ferentstratigraphic sections; (2)theareabetweentheSantaYnezMountains andtheSantaMariaRiverwasatopographic highduringthetimewhentheVaquerosandRinconormations werebeingdeposited elsewhere intheregion,andtheObispo-Tranquillon volcan'crockshavebeenerodedfromthisregion;or(3)thedevelopment oza'ull-apart basin(the"formation ofpull-apart basinsisdis-cussedbyCrowell,1974)zollowing thedeposition oftheVaqueros, Rincon,andObispo-Tranquillon zormat'ons. Thefirsthypothesis, namelylargepost-Monterey Formation orObispo-Tranquillon volcanicrockstrike-slip alongtheSantaMariaRiverfault,isdifzicult totest.Ifright-slip alongthefaultdidoccur,'ttheObispovolcanicrocksformerlyneartheintersection oftheSantaMariaRiverandSantaMariaMesafaults(Fig.1)wouldhavebeenmovednorthwestward and'nowwouldbeburiedbeneaththePismosanddunesoxliebelowSanLuisBayinthePacificOcean'(Jennings, 1959;HallandCorbato,1967;Hall;1973)-Thesecondhypothesis, thatis,priortothedeposition oftheMontereyshalestheareabetweentheSantaYnezMountains andtheSantaMariaRiverfaultwasatopographic high,ortheVaqueros, RinconandObispoformations weredeposited andsubsequently erodedaway,canezplainthedistribution oftheTertiaryrocks.However,theabsenceofCretaceous rocksinthisarea,buttheirpresenceboundingt'earea(Fig.1)andthepresence.ofEocenerocksnorth ~~4iandsouthoftheLittlePinefault,'near theLornaAltafault'(Fig.1),buttheirabsenceinthesubsurface inthevicinityofSantaYnez,approximately 15kmtothewestoftheLornaAltafault,andelsewhere inthebasinbetweentheSantaHariaRiver-Foxen Canyonfault(Fig.1),isdifficult toexplainbythishypo-thesis,unlessoneassumesthattheCretaceous orEocenerockswerealsoerodedIcompletely offofaFranciscan topographic high.Also,subsurface datadonot,provideevidenceofunerodedremnantsoftheseunits.Furthermore, ifthewedge-shaped SantaHariabasinwasahighduringorfollowing, forexample,thetimeofdeposition oftheVaquerosand.Rinconinorsurrounding theregionandthedeposition oftheObispovolcanicashinamarineenvironment withinthebasin,itwouldrequireanunusualhistoryforthebasin.Theeventswouldhavebeen:(a)thedeposition ofthenon-marine Sespe-Lospe formations, (b)thedeposition oftheshallow-water marineVaquerosSandstone followedbythedeep-water deposited ~~conShaleeithersurrounding thebasinorwithinthebasin,(c)thedeposition oftheObispotuffwithinamarine,basin,(3)the'eep-water basinwouldhavebeenuplifted,'ith theVaqueros, Rincon,andObispoerodedaway,and(3)the"theareawouldhavebeendown-dropped almostsimul-taneously w'ththeerosionoftheObispoFormation sothatthedeep-water PointSalorLowerMontereyandMontereyFormations couldbedeposited inadeepening basin.NotethatthebaseoftheMontereyFormation isbetween10,000and15,000feet(3048to4572m),belowsealevel(Fig.1).Thusawedge-shaped highwould'IhavetopersistfromOligocene toMiocenewhiletheareasurrounding'he highwouldbesubsiding, andthenthehigh-standing landmasswouldhavetosubsiderapidlyintheHiocene andPliocenetoallowdeep-water PointSal,MontereyandPliocenesediments tocoverthesupposedhigh-standing landmass.Comparisons oflithologies andstratigraphic sections(Table1)tendtosupportthethirdmodelforthedevelopment ofa.SantaMaria-Lompoc pull-apart basin,althoughdetailedstratigraphic andlithologic studiesareyettobemade.InthewesternSantaYnezMountains thestratigraphic sectionisunlikethatnorthofSantaYnezValley(Lompoc,Buellton, SantaYnez,,Fig.1),.butit.agreesrelatively closelywiththestratigraphic sectionnorthoftheSantaMariaRiver-Little Pinefaultsystemnearly45kmto.thenorth(nearSantaMaria,Fig.1,Table1).Thestratigraphic sectioninthewesternSantaYnezMountains (eastofPointArguello, Fig.1)includes: (1)Franciscan melangeandHondaFormation (457m),(2)Cretaceous rocks(2743m),(3)Oligocene andEocenerocks(1981m),(4)Sespe-Lospe formation (91m),(5)Vaqueros-Rincon units(213m),(6)Tranquillon Volcanics (365m),and(7)MontereyFormation (914m).TneTranquillon Volcanics arethesameageastheObispoFormation (Tranquillon Volcanics: 17+1.2(basalt), 16.8+.5(tuff),16.1i..6(tuff)m.y.;ObispoFormation: 15.3+.9,16.3+.5,15.4+.5,15.3+.5,16.5+.8m.y.;Turner,1970).Thissequenceofrocksdoesnotcorrespond exactlywiththaonthenorths"deofthebasin,namelynorthoftheSantaMariaRiverfault,andareconstruction oftheTertiarygeologichistoryoftheregionpriortopullingapartofthebasinisrequiredtounderstand whyexactcorrelations cannotbemade.Ageneralized possibleTertiaryhistoryofthedevelopment oftheSantaMaria-Lompoc basincouldbeasfollows.Figure2ashowsageneralized paleo-geologicmapafterthedeposition oftheGaviotaFormation ofOligocene ageandolderrockunits(Cretaceous, K;Eocene,E).Beforedeposition ofthenon-marineSespeFormation therecouldhavebeenstrike-slip alongtheinferredfault,asshowninFigure2b(diamonds). Later,obliqueriftingalongthisfault(postObispo,postFig.2dtime)wouldaccountforthedevelopment ofthe.SantaMaria-Lompoc basin.Theinferredfault(diamonds) iscalledtheLompoc-Solvangfault(Fig.1).Itsinferredpresenceissupported bythefactthat northofitsapproximate locationthestratigraphy (knownfromexploratory oilwells)ismarkedlydifferent fromthatsouthoftheinferredfault.Figure2cdepictsagenerali.zed paleogeologic mapbeforethedeposition oftheMontereyFormation. Sespe-Alegria formations (inpartLospeFormation), VaquerosSand-stone,RinconShale,andObispo-Tranquillon volcanicrocksunconformably over-lietheFranciscan rocks(F),Cretaceous rocks(K),Eocenerocks(E),andOligocene (GaviotaFormation) rocks(0).(F,K,E,and0shownasdottedandburiedcontacts)- Thefault(diamond) waseitherburiedorwascontinuously orsporadically activeduringthedeposition oftheTertiaryrocksshowninFigure2c.'\Subsequently, aseriesofpull-apart basinsmayhavedeveloped alongthepresentcoastalpartofcentralCalifornia, onesuchbasinbeingtheSantaMaria-Lompoc 5hzbasin.TheSantaMaria-Lompoc basinwasprobablylatertransected bySanzoneSimeon-Hosgri faultv(Eall, 1975a).Afterdeposi.tion oftheObispo-Tranquillon volcanicrocks,theformation oftheSantaMaria-Lompoc basin(Fig.2d)began.withthedevelopment alongtheright-slip transform Lompoc-Solvang-Santa MariaRiver-Foxen Canyon-Little Pinefaultsystem,ortherewasrenewedmovementalongthisalreadyextantfaultsystem,'possibly duringtheLuisianAe(14m.y.b.p.). Themarginsofthebasinwereformedbythe.Lompoc-Solvang fault(diamonds) (orpull-apart shoulder) andtheSantaMariaRiver-Little Pinefault(triangles) (or.pull-apart shoulder). Right-slip alongthefaultprobablyaccompanied dip-slipandthelateMioceneandPlioceneseasfloodedthedeepening basin;notethatnearLosAlamosthebaseoftheMontereyFormation isnearly4,572m(15,000feet)belowsealevel(Fig.1),thatthemaximumsubsurface thickness oftheMontereyFormation isprobablymorethan1,524m(5,000feet)thi.ck,andthemaximumout-cropthickness atthemarginsofthebasinisapproximately 655m.(2150feet).Itissuggested thattheSantaMariaRiverandLompoc-'Solvang faultsarepartofthesametransform-right lateralfaultsystemandbeforethelateMiocenepull-apart,toproduce*the SantaHaria-Lompoc basin,wereprobablyasinglefaultorfaultzone.Theformation ofthelateTertiarypull-apart basin,withmotiontvectorsofextension paralleltothestrike-slip faults,beganfollowing thedeposition oftheObispo(Tranquillon) Formation, probablyduring.themiddleMiocene(14m.y.b.p.). Hallsalongthefaultmarginsmayhavebeguntosagandpullapartasearly'astheearlyOligocene, orevenearlieriftherewasmorethanIoneepisodeofrifting.TheFranciscan rocksareweak,easilyfolded,faulted,andstretched orbecameevenmoretectonically brecciated. Whatoccurredtothedeepercrustallayersisunknown,buttherewasnotmassiveextrusion. Duringt¹openingofthebasinonlyminorvolcanicflowsorintrusions (e.g.,those.nearPointSal)occurredcontemporaneously, withthepull-apart and'thestretch-ingoftheF"ancscan.Rotational movement(Fig.2e)orbendingaccompanied formation ofthe.pull-apart basin.ThismovementresultedinachangeoftrendoftheLompoc-Solvang fault(Fig.2d)fromnorthwest toeast-west (Fig.2e).Therotationorbending~~ouldaccountforthedistribution fotheCretaceous (K),Eocene(E),andOligoce"e (0)rockssouthoftheinferredLompoc-Solvang faultandmayhaveplayedaroleinorduringthegeneraldevelopment oftheTransverse Ranges.Thamountofcounter-clockwise rotationisreducedifthe'Lompoc-Solvang faultinitially hadamorewesterlytrend.The'maximum pull-apart isbetween40and.50kilometers. Becauseofprobablestrike-slip alongtheLompoc-Solvang-SantaMariaRiver-Little Pinefaults,theCretaceous andEocenerocks,GaviotaFormation, VaquerosSandstone, RinconShale,andObispo-Tranquillon volcanic'IrocksnearPointArguelloprobablywereincloserjuxtaposition,.initially withrocksofthesamelithology andagesatthelatitudeofCamuesafault(Fig.1)ornearZacaLake.(Jennings, 1959).thanwithrocksneartheSantaMariaRiverfault.Thatis,therocks"south ofLompocandSolvang,intheTransverse Ranges,havemovedalongaright-slip transform Lompoc-Solvang-Santa'Haria River-Little 8Pinefault,thebasinopenedalongthisfault,rotationorbendingoccurred, andtheLompoc-Solvang faultandrockssouthofthefaultwerebroughtintotheirpresentposition. Left-slip occur'red atalatertimealongaSantaYnez-Pezzoni faultsystem(partially showninFig.1).Following thedeposition ofthe'lateTertiarysediments (Sisquoc,'oxen, Caxeagaformations), withinthedeepenedbasin,apartofitwasmovedmorezonethan80kmtothenorthalongtheSanSimeon-Hosgri fault(Hall,1975a).Itisunlikelythat.theslipislessthan80km.Evidenceforthisunlikelihood isprovidedbythefactthatthepackageofrocks,intheSantaMariaregion(i.fe.,Jurassicophiolite., chert,andshale,LospeFormation, MontereyFormation, andzone'liocenerocks),whichweremovednorthalongtheSanSimeon-Hosgri faulthasadistribution limitedtotheSantaMariabasin.Atitswidestthebasinisabout50kilometers (30miles).However,itwillbenotedthattheknowndis-tribution oftheJurassicophiolite, chert,shale,LospeFormation andassociated youngerrockstha-cropoutnearPointSalareknownfromthesubsurface inanareaoflessthan19km(12miles).ThedistancebetweenPointSalandtheSanSimeonarea(Fig.3)ismoethan100km(62miles),thediameteroftheuniquepackageofrocksintheSantaMariaareaislessthan20km,thustheoffsetwouldbeatleast80km,andmorelikely95km.Thereleasing halfbend,depictedatthesoutheast endofthepull-apart basininFigure2d,wouldhavehadamirrorimageatthenorthwest end,butthishasbeentruncated bythe'anSimeon-Hosgri faultandisnow100kmtothenorthatSanSimeon(Fig.3).ThePlioceneCareagaSandstone atSanSimeonsuggeststhatthe80to95kmof,right-slip alongtheSanSimeon-Hosgri faultoccurredduringthelast5m.y.Theearliest'strike-slip movementalongtheSanSimeon-Hosgri faultwouldprobablybe9to13m.y.'learlyallmovementtookplacealongthefaultIffollowing theformation ofthepull-apart structure. ~p~~~~Someinvestigators havesuggested thattheoffshoreexploratory well,Standard-Humble ffl(Fig.3),containsasectionofrocksthatismostlikethatonshoreatornearthesamelatitude(Santa'FeriaValley).Theoff-shorewellencountered thefollowing section:topoftheSisquocat3402ft(thickness 635mor2082ft);topMontereyat5484ft(thickness 358mor1176ft);topofvolcanicash (probably Obispo-Tranquillon volcanics) at6660ft(thickness 122m,or400ft);topof"volcanic rocks"(probably Lospe,personalcommunication DavidHowell,1977)at7060ft(bottomofwellat7797ft).Onshore,atornearthesamelatitude, welldata(Woodring andBramlette, 1950,crosssectionA-A')provideinformation toshowthattheMontereyFo~~~~tion lieseitherontheLospeordirectlyonFranciscan rocks;whereasthewellprobablycontainsvolcanicash,'oftheObispoorTranquillon volcanicrocks.Thesectionintheoffshorewellmightbestbecorrelated onlandwithrockseithersouthoftheLompoc-Solvang fault(i.e.,nearPointArguel"o;seeDibblee,1950,geologicmap)orpossiblywitntheStandardOil"Sh~-.-ers":"-1 southofPurisimaPoint(section 4T.7S.,R.35W.),/herc.morethan32km(20miles)southofthewellontheopposite-side ofthetheS~gv~roSanSimeon-Hosgri faultzone.ThepartiallogofwellshowninFigure1isprobablyincorrect andtheunitsencountered wereprobably'IMontereyoverlying Obispo-Tranquillon volcanics, whichinturnoverliestheLospeFormation. Thewellwasdrilledin1928and1929.Thus,theoffshorewellcouldeasilysupportbutdoesnotdetractfromthemodelofapull-apart basinandoffsetalongtheSanSimeon-Hosgri faultmeasuredintensofkilometers. Continuous orrenewedlateTertiaryorQuaternary movementmusthaveoccurredalongtheSanta>fariaRiverfault.Evidenceforthissuggestion isprovidedbythegeologyintheTwitchell Damquadrangle 01all,1977)andthegeomorphology andlateTertiaryandQuaternary geologyalong*the FoxenCanyonfault(Fig.1).IntheTwi.tchell Damquadrangle theRestHuasnafaultfaultsQuaternary depositsandisinturntruncated by,oristhesameageas,theSantaMariaRiverfault.OTHERNEARBYREGIONALBASINSTheMorroBaybasintothenorthofSantaMariabasin(50kmnorthofSantaHaria)showssimilarrelationships tothedevelopment oftheSantaMariabasin.Althoughthecorrelation ofrocksatthemarginsoftheHorroBayTertiaryoasinisnotasclearasthoseatthe,marginsoftheSantaMaria-Lompoc basin,theHorroBaybasinmightalsorepresent apull-apart structure. ThebasinmayhavebeguntoopenduringtheearlyOligocene andthedacite-felsite rocksofthatage,formingHorroRockand12to13othermajorint~sivemassesinthe'area(including theCambriaFelsite), mayreflectaperiodofvolcanism andintrusion atdepthduringbasinopening.Sucha.interpretation wouldhavetoaccountforthefactthattheriftedintrusive rocksweredaciticandnotbasalticrocks.Equallyasspeculative isthesuggestion thattheHorroRock-Islay Hillcomplex(ErnstandHall,1974)wasrotated10to15degreestothewestafteremplacement, andthattheCambriaFelsiteinCambriaandatRockyButte'Hall, 1973,1974,1975b;HallandCorbato,1967;HallandPrior,1975) ~.~werealignedwiththelforroRock-Islay Hillcomplexatthetimeofemplacement duringtheOligocene. Analternative explanation fortheHorroBaybasiniskthatitisanuplifted, tippedfaultwedgebasin(seeCrowell,1974)boundedbythePismoandHuasnainclinedsubsidence basins.Suchasuggestion doesnotprecludepre-midorlateMiocenecounterclockwise rotation. Ifthe'Horro Baybasinisanupliftedtippedbasin,itmusthavesubsidedduringlateliioceneorPliocenetimebecauseremnantsofrocksoftheseagesarepresentwithintheregionsboundedbytheEdna-LosOsosValleyandWestHuasnafaultsystems.ThesefaultsformthemarginsofthehlorroBaytippedfaultwedgebasin.Sb~MARYBasedonthegeology,stratigraphy, distribution ofsedimentary andvol-canicrocks,andlithologic similarities ofwidelyseparated rocktypes,thereisevidencetosupporttnehypothe'sis thattheSanta?4ria-Lompoc basinisapull-apart structure. Thefault-bounded basiniswedge-shaped withthemaximumpull-apart beingnearly50km.Thebasinmayhaveundergone recurrent periodsofr'ing,perhapsduringthedeposition oftheRinconShale,themostrecentofwhichtookplaceapproximately 14m.y.'b.p-Thepresentlocationandorienta-tionoftheCretaceous tomiddleMiocenerocksintheWesternTransverse RangesareduetorightslipalongtheLompoc-Solvang-Santa ?fariaRiver-Little Pinerightlateraltransform, subsequent counter-clocLmise rotationorbendingoftheregion,andlateTertiaryand'Quaternary leftslipalongtheSantaYnezfault.TOtherbasinsintheregion,e.g.PismoandHuasna,arepossiblytippedsub-sidencebasins(Crowell, 1974)andtheMorroBaybasinisatippedfaultwedgebasin(Crowell, 1974).Allstructural basinswereprobablyformedbetweenlargestrike-slip faultsduringlatemiddleorlateHioceneandwereinpartlateraffectedbymovementalongsuchfaultsastheSanSimeon-Hosgri faultaone 12andRinconda,Fault (Dibblee, 1976).Therehasapparently beenat.least80orQoaa95kmofrightslipalongthe~L~~i~>~-~~>~<< ~~Itsince thePliocene(duringthelast5m.y.)andfollowing theformation oftheSantaMaria-Lompoc pull-apartbasin.ACKNOWLEDGi1ENTS IwishtothankJ.C.Crowell,W.G.Ernst,W.R.Dickinson, andEliSilverfortheirhelpfulcommentsanddiscussions oftheconceptsexpressed inthispaper. .~REFERENCES 13Crowell,J.C.,1974,OriginoflateCenozoi'c basinsinsouthernCalifornia, inTectonics andSedimentation, editedbyW.R.Dickinson: Soc.Econ.Paleontologists andMineralogists Spec.Paperno.22,pp.190-204.Dibblee,T.W.,Jr.,1950,Geologyofsouthwestern SantaBarbara'ounty, California: Calif.Div.MinesBull.150,pp.1-84,maps~Dibblee,T.W.,Jr.1976,TheRinconada andrelatedfaultsintheSouthernCalifornia CoastRanges,California, andtheirtec-tonicsignificance: U.S.Geological SurveyProfessional Paper981,55p.Ernst,W.G.,andHall,C.A.,1974,Geologyandpetrology ofthekCambriaFelsite,anewOligocene formation, west-central Calif-orniaCoas"Ranges:Geol.Soc.AmericaBull.,v.85,pp.523-532.Hall,C.A.,Jr.,1975a,SanSimeon-Hosgri faultsystemcoastalCali-fornia:Economicandenvironmental implications: Science,v.190,pp.1291-1294. Hall,C.A.,Jr.1975b,GeologictfapoftheSanSimeon-Piedras Blancasregion,SanLuisObispoCounty,California: U.S.Geological SurveyMisc.FieldStudiesMapMF784,scale1:24,000. Hall,C.A.,Jr.,1977,GeologicMapoftheTw>>4~ii><~>>"P~">~~k>~=~"""gdTePuSqaef Puadringlc>> SantaBarbaraCounty,California: U.S.Geological SurveyMisc.FieldStudiesMap,scaleof1:24,000(inpress). 'IReferences continued Hall,C.A.,Jr.andCorbato,C.E.,1967,Stratigraphy'nd structure ofMesozoicandCenozoicrocks,NipomoQuadrangle, SouthernCoastRanges,California: Geol.Soc.AmericaBull.,v.78,p.559-582.Hall,C.A.,Jr.andPrior,S.W.,1975,GeologicMapoftheCayucos-SanLuisObisporegion,SanLuisObispoCounty,California: U.S.Geological SurveyMisc.FieldStudiesMapkfF686,scale1:24,000Jennings, C.V.,1959,GeologicMapofCalifornia, OlafP.JenkinsEdition,Santa~fariaSheet.IJennings, C.H.andStrand.,R.G.,1969,GeologicMapofCalifornia, OlafP.JenkinsEdition,LosAngelesSheet.Turner,D.L.,1970,Potassium-argon datingofPacificCoastMioceneforaminiferal stages:Geol.Soc.AmericaSpec.Paper124,pp.91-129.Voodring, H.P.,andBramlette, M.N.,1950,Geologyandpaleontology oftheSantaMariadistrict, California: U.S.Geological SurveyProf.Paper222,142pp.,maps. WesternSantaAeofrockunitsYnezMountains SantaMaria-LomocbasinCuyama-Santa Maria-SisuocRiversareaPliocenePlioceneMiocene-Fliocene MioceneMioceneMioceneOligocene-Miocene .Oligocene Oligocene -SisquocFm.MontereyPm.L.Mont.I'm.Tranquillon Volcanics RinconShaleVaquerosSs.Sespe/Alegria Pormations CareagaSandstone PoxenHudstoneSisquocI'in.MontereyI'm.Pt.SalPm.Sespe-Lospe Formations MontereyFm.Pt.SalPm.ObispoFm.RinconShaleVaquerosSs.SespePm.Oligocene EoceneCretaceous .JurassicCretaceous-Jurassic orJurassicGaviotaPm.EocenerocksCretaceous rocksHondaFm.Franciscan rocks'Knoxville" Fm.Pranciscan rocksorophiolite Cretaceous rocksJurassicshaleFranciscan rocksTable1Generalized pre-Pleistocene stratigraphic sectionsfromthemarginsoftheLompocSantaMariabasin,westernSantaYnez.Mountains (Dibblee, 1950),SantaMariaandLompocbasins(Woodring andBramlette, 1950),andtheareanorthoftheSantaMariaRiver(Hall,1977),SantaBarbaraCounty,California. "~FIGURECAPTIONS16LCIII'FIGUREl.Generalized paleogeologic map(pre-Monterey Formation andgeneralized structure contourmap.(baseofifonterey Formation), SanLuisObispoandSantaBarbaraCounties, California. Generalized distribution ofselectedstratigraphic unitsisfromJennings(1959),Hall(1977),.re- .donnaissance .geologicmappingintheSisquocandLompocareas,andfromcoreholedatasuppliedbytheCalifornia DivisionofOilandGas,fromwelllogsSantaHariaDistrictOffice.Incomplete welldataareshown:i~lon-tereyFormation, Tm;PointSalFormation, Tps;"Temblor" Formation,, Tt;RinconShale,Tr;VaquerosSandstone, Tv;LospeFormation, Tl;Franciscan rocks,KJf;Jurassicshale,Jsh;Jurassicophiolite, Jo.A.Sylvester (Univ.Calif.,SantaBarbara)reports(personal communi-cation,1977)thepresenceofafaultinthevicinityofSantaYnez4.andSolvangwithanorthwest trend.Ibelievethatthisfaultisacontinuation ozthePezzonifaultandpassesnearLosAlamos;-theexactlocation, however,isunknown;'IFIGURES2a-2e.Hypotheticalpaleogeologic maps.UFigure2a.-Hypothetical paleogeologic mapfollowing orduringthedeposition oftheGaviotaFormation ofOligocene age.CoastalpartofCalifornia. rFigure2b.-Hypothetical paleogeologic map,following strike-slip alongtheLompoc-Solvang-Little Pinefaultandbeforethedeposition ofthe7Sespe-Lospe formations. CoastalpartofCalifornia inthevicinityofwhatisnownorthwestern SantaBarbaraCounty.Theinitialtrendandamountofstrike-slip isnotknown. Figure2c.-Hypothetical paleogeologic mapfollowing deposition oftheObispo-Tranquillon volcanicrocks.Following deposition oftheGa'viotaFormation andstrike-slip ontheLompoc-Solvang fault,theSespe(andthemarineequivalent Alegria)(coarseswirleddots),Vaqueros(finerandomdots),RinconandObispo-Tranquillon rocks(finemixeddots)weresuccessively (northeast-southwest trend)andunconformably deposited upontheunderlying Franciscan (F)(vertically ruled),Cretaceous (K)(horizontally ruled),Eocene(E)(nopattern), andsomeOligocene (0)(diagonally ruled)rocks.Figure2d.-Hypothetical paleogeologic mapshowinggeologyofnorthwestern SantaBarbaraCountyapproximately 14m.y.b.p.Basinpull-apart begantodevelopalongtheLompoc-Solvang-Little Pinefaultcon-te-poraneously withthebirthoftheSantaMariaRiver-Foxen Canyon-LittlePinefaultzone.Vaqueros, Rincon,andvolcanicrocksareatthemarginsoftheopeningbasin,butareremoved,exceptforremnantsleftonthestretched andtectonically mixedFranciscan t;rocks,fromthecenterofthebasin.Cretaceous, Eocene,andOligo-cenerocksalongwiththeoverlying Sespe,Vaqueros, RinconandObispo-Tranquillon rocksaresouthwest oftheLompoc-Solvang-zoneLittlePinefault(diamonds); Franciscan andremnantsoftheSesperocksliebetweenthetwofaults,andCretaceous, Sespe,Vaqueros, Rincon,andObisporockslienortheast oftheSantahfariaRiver-FoxenCanyon-Little Pinefaultzone(triangles). Strike-slip probablyaccompanied thedevelopment ofthepull-apart basin. ~'~~18Figure2e.-Generalized pre-lateMiocene'paleogeologic map.Theproposedmodelsuggeststhecounterclockwise rotationoftheLompoc-Solvang-LittlePinefault,rotationthathasoccurredsometimesincethelatemiddlepliocene. TheinferredLompoc-Solvang faultintheproposedmodelisthenorthernboundaryofTransverse RangesinthewesternpartofSantaBarbaraCounty.FIGURE3..LocationoftheSanSimeon-Hosgri faultz'one,SantaMariaRiver,Lompoc-Solvang, andotherfaults.,Spots(Ti~Tertiaryintrusive) indicatesitesofOligocene hypabyssal volcanicrocks,including theiforroRock;Islay HillvolcanicrocksandsimilarrocksinthenorthnearRockyButte.LocationofStandard, OilCo.ofCalifornia-HumbleOilCo."Oceano81"isshownwestofSanSimeon-Hosgri faultsystem. PIIrisimo PoinlRjntArguelioGENERALIZED PALEOGEOLOGIC MAP'tPItEMOilTEREYI'ORMATIONl ANDGENERAI.IZED STRUCTURE CONTOURMAP(13ASEOFMONTEREYFORMATIONl SANLUISOBISPO-SAN'I'A 13AR13ARA

COUNTIES, CAI.IFOI~WIA On/EXPIANATIONOara~Oll'-":I;Wa:IHaaaaafaallQGUAoALupE Cretaceous rocksf="..]VaquerosSandstone-JtFranciscan melange-I-'-.:MRinconShoto.ophiolile complex4X<~P;)LB4/(lllPGETTERAVIA4Jo'I3OoooaIIEooi>>'oI."..'.-;:,';

.'espe-Lospe Formotion sSerpenlinile LimitofMontereyT~~EE~SantaMarioRiverfault0C~Oy0-505t0QORCUTT-.'0X~~ip/io~LimitofLospeFormotion ,p/~~4/oCASMALIAI--X'e,'iiX~~~.:-:--In<<-Structure contourline'EE0Cp,.4K=<iNeo'a~~fpu//--Fault~~~o-o->Lompoc-Solvang faults6~QLOSALAMOS~(oKJtIa*Tmsrn(4nlV~4Exploratory oilwellou//o~BOE+~ŽHaaaaIaa~+L,~~~OBUELLTOU OOOUTOTl,'EE+BBITBBEforllEp~Ex4ro/jr~EnE~Tao4f$onto)n-~~<u//-"-+4Q~(OIIO--~/GAVIOTAPASSfoulg50miles/15km.'aPoifltConeepifen PacificOcean =CRITACEQUS'OCENE FRANCISCAROCKS1'llOLIGOCENE lGAVIOTAl EOCENEOLIGOCENE xfGAVIOTAl 8/8/1zrgfllit'rer!ii:rrte'-'"::OBISPO-'.."': ".",ir-"lt.TR.4iQLILLO<<,, ',i'..',.-,*",.<<,,,;.'e',.";! "Y.;:-,.":,"::.; 't"~lljjtfCefe~e~,'e~IIK.:;,".':'OBISPO.:'.-'TRAhQUILLOtr -.rtfr[!tileSESl!~jm~~~e,jhT}PFrrt~ettreeejetetrlifjece~r'jtttSSEPijirf'::.',..'.:';,.":::e."!",,:;.'-',li, vAQUERQsgll iGic':,".e:,t'.::~..:.;![i t~$-l<!.~J!,RZ'.-CO'~ l,IIlCf.)tttOaIS>.igll,lijff!e.ll!i~ '!l,lljf,'-OBISPO--,THANQUILL'Oi -Rr~ro~",.'-',-" "',j!-;-SFRPEj i~"-;...VAQUEROSI-20 I~~36o35o0CapeSonMartin'.~~~~ee~~~~~~~~~~~~~~~OCte)MorroBoy(0~ePt.SonLuis~eeI:.(q~C~~~pVp~p00Gg04/C0CDeeeArroyo6rondeSp0IL0+oOq.Santo4@~MorioPG010kilometers SantoMorio-LompocBasin~~~~~~~~~~~RoggedPt.~e~~~~~~~~~lPockyTj(dpt.PiedrosBlancosSanSimeonSonSimeonPt.PosoRobicsDc'.+CambrioOilOGPt.Buch~~~ee~~~e~~p~ee~ee~~~~ee'ee~W~~~~~~~~~~Stondard-.Humble .+'-.OceanoNl'e0:.~Pt.SallQmilesHeod~~PurisimoPt.MapLocation~~~~~e~e~~~Lompoc~7~~PbAruello~eeee~ee~e~eeee~ee~e~ePt.Conception:, ~e2lo ~' II~~IATTAC11MENT J~~MARINEGEOLOGYANDTECTONICHISTORYOFTHECENTRALCALXFORNIA CONTINENTAL MARGINEliA.Silver2DavidS.McCulloch 3JosephR.Curray4SantaCruz,California MenloPark,CaliforniaLaJolla,California ABSTRACTThegeologyofthecentralCalifornia continental marginshowsahistoryofearlyTertiarysubduction oftheFarallonplatekandfollowedbyaMioceneandyoungerperiodofhighanglefaultingandbasinformation corresponding totransform movementbetweenthePacificandNorthAmericanplates.Seismicreflection profilesshowirregular structural surfacesontheoldersedi-mentaryrocks,whichareoverlain-by mildlywarpedyoungerstrata.'argeshelfbasins,including the.SantaMaria,Sur,OuterSantaCruz,Bodega,andPt.Arenabasins,areboundedbydown-to-basin faults.Thestructural styleofmost'fthesebasinsissimilar,althoughthePt.Arena,OuterSantaCruz,SantaMariaandSurbasinsprobablyrestonFranciscan basementandtheBodegaliesongraniticbasement. Drillingdatasuggest.anearlysynchronous originforthesebasinsin'middleMiocenetime(HoskinsandGriffiths,1971).Analysisofpi..esently available dataforthehistoryoffiniteplatemovements sincethemiddleCenozoicsuggestsawestwardshiftinthedirection ofmovementofthePacificplaterelativetotheNorthAmericanplateinthisregionabout10millionyearsago(m.y.a.). Suchachangeinplatemotioncouldhaveprovidedasufficient extensional component ofmovementtoresultinbasinformation, possiblyalongtheolderstructural grainofthemargin.SomeoftheQuaternary faultingishighanglereverseinsense,indicating acompressional component actingoverapproximately thelastmillionyears.ltispossiblethattheinstantaneous movementbetweenthePacificandNorthAmericanplateshasbeenchangingcontinually duringthepast30m.y.Thedistribution ofgraniticrocksoftheSalinianblockonthecontinental marginconstra'ins measurements ofoffsetalongtheSanAndreasandSanGregoriofaults.TheSanAndreassystemoffaultsshowsatleast550kmandamaximumof600kmoffset,basedonthenorthernextentofgraniticbasementunder-lyingFarallonridge.TheSanGregoriofaulthasanestimated offsetof100+15km,basedonoffsetofthesouthernendofFarallonridge.Theseobservations supporttheideaofslivering withintheSalinianblock(JohnsonandNormark,.'1974). However,earlyTertiarypaleogeographic reconstructions byNilsenandClarke(1975)requiresomeSalinianoffsetbyearlyPaleocene, incontrasttothemodelofJohnsonandNomark.Wefavorapproxi-mately100kmofoffsetduringlatestCretaceous toPaleocene timeand450to500kmoffsetafter22m.y.a.GraniticbouldersdredgedfromSantaLuciaBank,farwestoftheSalinianblock,raisethequestionofeitherthepresenceofgraniticfaultsliceswestofJ-2 ~~I~1theSalinianblockorextenivetransport ofthesebouldersfromSaliniansourceareas. Manuscript ReceivedAccepted2.University ofCalifornia, SantaCruz,California 950643.U.S.Geological Survey,MenloPark,CA940254.-ScrippsXnstitution ofOceanography, LaJolla,CA92093WethankW.R.NormarkandH.C.Wagnerforcarefulreviewsandsuggestions. D.G.Moore,R.vonHueneandH.G.Green'egenerously allowed,useofunpublished reflection

profiles, andtheNationalOceanSurveygenerously alloweduseofunpublished gravityandmagneticdata.WearegratefultoT;C.Worsleyforpaleonto-logicanalysis, toL.Silver,E.C.BeutnerandL.Leefoxpetrologic examination ofsomeoftherockscollected, andtoC.McHendrie andRobertBruneforagreatdealofeffortinproviding computeroutputofmuchofthedata.Wearegratefulfordiscussions withandideasfrom,C.G.Chase,T.Atwater,S.A.Graham,W.R.Dickinson, W.Gawthrop, C.H.Hall,D.Hamilton, J.Crouch,E.C.Bcutner,J.C.Crowell,T.Nilsen,andtoagreatJ'anypeople,toonumeroustomentionortoproperlyrecall,whocontributed tothi+workinverysignificant ways.Ourlackofcitationhereisnotthroughlackofgratitude orindebtedness.

Wefinallythankthecaptains, crewsandscientific partiesofmanyexpeditions totherollingseasoffcentralCalifor'nia fortheircooperation andsupport. INTRODUCTION Thecontinental marginoffCentralCalifornia, betweentheMendocino andMurrayfracturezones,hasundergone acomplextectonicdevelopment duringCenozoictime.Atwater(1970)hasinterpreted themagneticanomalypatterninthenortheast Pacifictoimplysubduction oftheFarallonplate(McI(enzie andMorgan,1969)beneaththemarginintheearlyTertiary. Approximately 30m.y.a.subduction begantoceasealongCentralCalifornia andstrikeslipfaultingsubsequently beganalongthemargin.IThesetectonicprocesses probablyplayedamajorroleindevelop-ingthestructure ofthemargin.Thepresentstudydescribes thatstructure andevaluates hypotheses fortheCenozoictectonic,. evolution ofthecontinental margin.Geophysical studyofthemarginhasincludedsinglechannelseismicreflection profiling, utilizing highandlowenergysoundsources,onapproximately nineexpeditions oftheScrippsInstitu-tionofOceanography'nd oftheU.S.Geological Surveysince1964(Fig.1).Additional detailedstudiesareavailable forMonterey.Bay(Greene,1970),atPointArena(unpublished PacificGasandElectricCompanyreport)andbetweenPointArguelloandPointSur(McCulloch andothers,1977;Buchanan-Banks andothers,1978).GravityandmagneticdatawereobtainedbetweenSanFrancisco andPointArguelloandmagneticdatanorthtoCapeMendocino. Wewerefortunate tohaveaccesstoanextensive gravity,magneticandbathymetric surveydonein1970bytheNationalOceanSurvey. Sea.floorrockswereobtainedbydredging(Fig.1)onAntipodeandSeven-Tow expeditions oftheScrippsXnstitution, onseveralU.S.G.S.expeditions oftheR/VKelezandR/VBartlettandfrompreviousworkers(Hanna,1952;UchupiandEmery,1963;MartinandEmery,1967).HoskinsandGriffiths (1971)-hereafter ~abbreviated as(H-G)-published structural interpretations ofshelfbasinsbasedonShellOilCompanyseismicprofiles, dartcores,andwelldata.Thedatawerenotavailable tous,butwehaveusedtheirpublished mapsandcrosssectionsforagecontrolwheneverpossible. Forconvenience of'resentation ofthegeophysical resultsandstructural interpretation wedividetheCentralCalifornia continental marginintothreeregions:1)PointArguellotoMonterey(34to36.5'N);2)MontereytoPt.Reyes(36.5to38'N);3)Pt.ReyestoCapeMendocino (38to40.5'N).GEOPHYSICAL RESULTSPointArugellotoMontereyThedominantstructural featuresofthispartoftheconti-nentalmargin'are theSantaLuciabankandtheSantaMariaandSurbasins(Fig.2).ThebankisabroadhighboundedontheGastbytheSantaLuciabankfault(Figs.2and-3)andonthewestbythetopofthecontinental slope(seeprofiles16-28,Fig.4).TheSantaMariabasinoffshoreliesbetweentheHosgriandSantaLuciabankfaults(Fig.2).TheSurbasiniscontinuous ~li~~hwiththeSantaMaria,isboundedbycoastal'faultsontheeast(Fig.3),andsedimentthinswestwardagainstthenorthernpartofSantaLuciabank(Fig.5,'2-L10).. ThebasinsandbankmakeuptheArguelloPlateau(UchupiandEmery,1963).Thestructural development oftheregionwasdiscerned fromthegeo-physicaldata,butthetimingoftectoniceventsreliesondatafromthegeologyoftheonshoreSantaMariabasin,offshoredrillingbyoilcompanies (H-G),anddredging. TheSurbasin(Figs.2,3)iscrossedbyprofilesL2-L10(Fig.5,)andhasgreatestsedimentthickness inprofileL6.Theedimentthickenseastward, withmorethan.threekilometers ofsedimentverynearthecoast.Theshelfisnarrowhere,andisprobablyboundedontheeastbyafault.Thefaultissuggested bytheverticaloffsetinFranciscan rockthatprobablyunderlietheSurbasinoffshore, andareexposedalongthecoastline, anoffsetofatleastfourkilometers. Thefaultisalsosuggetedbyasteepgravitygradient(Fig.6).Thenearabsenceofdeformation inthesebasinstrata,andtheeaseofacousticpenetration suggeststhatthelayeredsectiononlineL6islargelyoflateCenozoicage.H-G(1971)interpret thebaseofthelayeredsectiontobelowerMiocene.Anuncon-formityoccurswithinthesectioninlineL2'(Fig.5)butitsageisnotknown.TheSantaMariabasinisdeveloped onlinesL12toL20,andinmanyprofilessedimentthickness isgreatestateitheredgeofthebasin(seelinesL16,L18,L22,L24,L26),assedimentwedgesthickentowardandterminate againstthefaultsthat Nboundthebasin.Atleasttwounconformities areseeninlinesL14toL28,especially welldisplayed inlinesL16andL20(Fig.4).Thelowerunconformity probablyseparates Mioceneandyoungerrocksfrompre-Miocene rocks.Theupperunconformity maybelateMioceneorPliocene. Anunconformity separating earlyTertiaryfromlateCenozoic(undated) rocksisbeautifully displayed onlinesL20,L22andL24.TheSantaLuciabankfaultformsthewesternboundaryofthebasinforabout150km.Thefaulthasitsgreatestphysiographic expression inlineL20(Fig.4)wherethe'seafloorisoffsetabout150m.Tothesouththefault,nearlyintersects awesttrendingfaultthatboundsthenorthsideofthechannelislandsplatform(Fig.3).However,therelationbetvreenthesefaultsisnotclear.TheeastsideofthebasinisboundedbytheHosgrifault'Nagner, 1974),whichcanberecognized asamajor*basement offsetontheinnerpartsoflinesL16toL26.Shallowwaterdepthsandringingmultiplereflections insomeprofilesact.toobscurethestructure. TheHosgrifaultisprobablyseismically active.Anearthquake ofmagnitude 7.3occurredinthevicinityofsouthernSantaMariabasinin1927,andByerly(1930)reportsthatatsunamioccurredalongthecoastofsouthernCalifornia following theearthquake. Recentrelocation studies(Gawthrop, 1977)placethe1927epicenter atthesouthernendoftheHosgrifault.TheHosgrifaulttrendsnorthward towardtheSanSimeonfaultonlandandisprobablycontinuous withit.Hall.(1976)presentsevidenceforrightlateraloffsetof80kmto100kmbymatching1 geologicsectionsatSanSimeonwestofthefaultandPt.Sal,80kmsouthandontheeastsideoftheIIosgrifault.ThesectionisJurassicthroughPlioceneandrestsonJurassicophiolite (Hopsonandothers,1973).TheexactlocationandbehavioroftheHosgrifaultbetweenSanSimeonandPointSurisuncertain, butthefaultisprobablycontinuous andmaycontinuenorthtoorbeen-echelon withtheSanGregoriofault,described below.BasementrocksappeartodirectlyunderlieupperCenozoicdepositsinthecentralpartoftheSantaMariabasin.ProfilesL16andL18showanarchedbasementreflector whichcorrespond withagravityhighandmagneticanomalies ofupto200nT(Fig.7).AcrustalmodelfittedtogravitydataonlineL18issatisfied byahighdensity(2.85gm/ccinthismodel)blockinthecentralpartofthebasin(Fig.8).Shallowbasementbeneaththebasinisindicated bypairedmagneticanomalies thatareelongated paralleltothebasinbutconfinedbetweentheHosgriandSantaLuciabankfaults(Fig.7).Thewesternanomalyispositive(>100nT)andtheeasternisnegative(>-100nT).Thenegativemagneticanomalycoincides withthehighdensityblockandmayb'ecausedbybasalticx'ocksoftheFranciscan assemblage -perhapspartofthePt.Salophio-litedescribed byHopsonandothers(1973).Itnowappearscriticaltodrillthesectionoverthisreflector toseewhetherit.issimilaroxdifferent. fromthesectionsmatchedbyHallacrosstheHosgri-San Simeonfaultasatestofwhetherthosesectionsaretrulyoffset80kmorhavecontinuityoffshore. \I~4~~ ~~JusteastoftheHosgrifaultisaseriesofNW-trending faultsthatstrikeintotheHosgriatananglebutdonotcut,thelargefault.Someofthesesmallfaultspossiblycut.Holocenesediments (Wagner,1974),suggesting thatbothfaulttrendsmaybeactive.TheageoftheSantaMariabasinisreportedtobelatemiddleMioceneonthebasisofdrillingbyShellOilCompany(H-G).ThisagedatestherelativeupliftofSantaLuciabankonthewesternmarginofthebasin.WoodringandBramlette (1950)'eport.thatmarinedeposition inthepresentonshorepartofthebasinbegaininthemiddleMiocenewiththePt.Salformation. Marineconditions continued therethroughPliocenetimeandmajordeforma-tionoccurredinthePleistocene. Localcompressional deformation isseeninSantaMariabasinoffshore. Figure9(profileLDMinFig.1)showsalargefoldofsedimentary rockbuttressed againstabasement. blockonitseastside.Thestructure mayhaveresultedfromlocalshearbetweenbasementrocks.SantaLuciabankformsasmoothtopographic surfacebuthasacomplexinternalstructure. TheblockfaultedstyleofthebankledH-Gtopostulate rigidgraniticbasementatdepth.Seismicprofiles(Fig.4,L20toL28),however,showacomplexly deformedinternalstructure withinthebank,suggesting anearlierphaseofdeformation thatwasneitherrigidnorblocklike. Thusthebankhasundergone atleasttwodistinctly different stylesofdeformation. Theolderfoldingdeformation ofthebankistruncated byanerosional unconformity, andinsomelines(Pig.4,L20andL24)theblockfaultingpot-datestheunconformity. If,asdiscussed below,graniticrocksarepresentbeneaththebank,theyaremorelikelypxesentassmallfaultslidesthanasacontinuous, rigidmass.Ourprofilesdonotshowacontinuous acousticbasementbeneaththebank.Threedredgehauls,D4,D5'ndD7,weretakenonthebank.Dredgehaul(D5)wastakenonafaultedoutcropontheeastsideofSantaLuciabank,crossedbyprofileL26(Fig.4).Thislatterdredgerecovered wellroundedbouldersandcobblesindica-tiveofsignificant transport priortodeposition, andalsosomerockfragments, assumedtobelocalbedrock.'hemostabundanttransported bouldersweremeta-conglomerate, meta-sandstoneg argillite, andmaficvolcanicrocks.In-placerocksincludedpholad-bored graniticsandstone andcalcarenite, chert,andonepieceofactinolite schist.Theschistwasveryangularand'Ieasilybrokenandprobablycouldnothavesurvivedappieciable transportation. DavidMoore(pexsonal commun.,1971)dredgedglaucophane schistveryneaxthislocation. Dredge4,locatedonlineL16(Figs.1and4),recovered severalroundedcobblesofquartzmonzonite andquartzdiorite.Themostcommonrocktyperecovered wasgraniticsandstone, withlesseramountsofpholad-boredphosphorite, somesiltstone, andmaficvolcanicrock.Thesandstone, siltstone, andphosphorite weremostprobablyinplace.Thegraniticcobbles,weretransported anunknowndistance. IndredgeD7,locatedonprofileL28(Figs.1and4),softgranitic sandstone wasthedominantrocktyperecovered. Thesizeand'ngularity ofthegraniticsandstone indicatethatitwasinplace.individual grainsareangulartosubangular, implyingrapiddeposition withlittlereworking. Quartzandfeldsparcommonlyshowundulatory extinction, andthemicasaredeformed,. suggesting thattherockhasundergone asignificant shearingorflattening deformation. Thesandstone issimilartothatfoundwithintheFranciscan assemblage, whichalsoisquartzrich,angulartosubangular, andinternally sheared(Baileyandothers,1964).Thegraniticcobblesandsandstone couldhavehadeitheralocal(favoredbyH-G)oradistantsource.Localsourcebodiescouldbeeitherintrusions orfaultslivers.' Distant.sourcescouldbefromtheSalinianblock(generally considered tobeanoffsetsliceofSierraNevadagranitic-metamorphic

basement, boundedby.theSanAndreasandSur-Nacimiento faults).Atthebaseofthecontinental slope,allprofilesshowabasinwith2kmormoreofsedimentfill.Profiles16;20,22and28showabasement, reflector passingbelowthelowerpartofthecontinental slope.XnlineL20,basinstrataoverlapcontinental slopedebris..Thesamerelations occurinlineL28,buthereseveralhundredmetersofstrataabovethebasementreflector passundertheslopedebris.lnlineL22thestructure ispartlyobscuredbyasmallfaultblockatthebaseoftheslope.Theseobservations suggestthatnotectonicdislocation hasoccurredalongthelowerpartofthecontinental slopeduringdeposition oftheuppertwothirdsofthebasinsediment.

~~Aninactive, northwest-trending fracturezoneoffsetsmag-neticanomalies, questioningly identified asanomalies 7and8,approximately 30m.y.oldbyAtwater(1970).Thefracturezoneismarkedbyaridgethatprovidesfurtherevidenceforthe"stability ofthelowersloperegion'(Figs.3;4,linesL18,L20,L22,andL24;Fig.7).Theridgeextendsontothelowerpartofthecontinental slopeinlineL24,anddredgingatthislocationyieldeddominantly fine-grained olivinebasaltandmanganese nodules.These.rocks(D6,Figs.1and4)arequiteunlikeallotherstakenonthismarginandareclearlyrepresentative ofaseamountorvolcanicridge.Thedredgesamplesindicatethatthefracturezoneridgeextendstothecontinental slope.Noappreciable lateraloffsethasoccurredbetweenthevol-canicridgeontheslopeandtheoffshorefractureridgeifthiscorrelation ismeaningful. Theageoftheridgecanbenoolderthantheseaflooroneitherside(about25to30m.y.).1ftheridgeformedclosetothetimeofseafloordevelopment, themostprobablecase,thenlittleornolateraloffsethasoccurredalongtheSantaLuciaescarpment sincethePacificandAmericanplatescameintocontactinthemiddleTertiary(Atwater, 1970;McKenzieandMorgan,1969).MontereytoPt.ReyesThedominantstructural featureoftheMontereyBayareaistheSanGregoriofault(H-G,1971;Greeneandothers,1973)whichcanbefollowednorthward andoffshorefromAnoNuevoPointtointersect theSanAndreasfaultsystemoffSanFrancisco, givingameasuredlengthof150kmfromsouthofMontereytoSanFrancisco. TheSanGregoriofaultprobablyseparates graniticbasementrocksontheeastinMontereyBayfromnon-granitic rockstothewest(MartinandEmery,1967;Greeneandothers,1973).Eastofthefaultisaseriesofnorthwest-trending. faultsthatdonotcrosstheSanGregoriofadult.Earthquake studiesshowthatboththeseNNtrendingfaultsandtheSanGregoriofaultareseismically activeandfirstmotionstudiesshowthatbothareundergoing rightslip(Greeneandothers,1973).Thispatternisstrikingly similartothatdeveloped eastoftheHosgrifault(Wagner,1974;Gawthrop, 1977).Furthermore, theSanGregoriofaultmaybethenorthward continuation oftheHosgri-SanSimeonfaultzonedescribed above.Xfthissuggested continuity isprovedcorrect,theaggregate lengthoftheSanGregorio-Hosgri faultzoneapproaches 400km.TheSanGregorioappearstooffsetgraniticbasementterranesatleast90km(Silver,1974)andMioceneandolderrocksasmuchas90to115km(Graham,1976;GrahamandDickinson, 1977).TheIsuggested offsetoftheSanGregoriofaultis,withinthelimitsoferror,equaltothesuggested offsetoftheHosgrifault,greatlyincreasing theprobability that.theyrepresent asingle,continuous faultzone.Tworidgesandtwobasinsliewest,andnorthwest ofSantaCruz.'heFarallonridgeiscomposedofquartzdioriteattheFarallonislandsandappearstointersect thecoastnorthofAnoNuevoPoint.Theridgecanbetracedcontinuously inseismicprofilesasfarnorthasPointArena(Fig.2),andshowsclearly 15asahighonthegravitymap(Fig.6).Thefree-airanomalyreaches50mgalnorthofthoFarallonislandsanddropstonearlyzerosouthwest ofHalfMoonBay.Thisgravitylowalongthe'idgemaymarkanolderosional ortectonicnotch.Apronounced positivemagneticanomalyismappedoverthesouthernpartoftheridge(~ig.7).Thenorthward extension ofthismagnetichighalongtheFarallonridgeislessintenseandcannotbecontoured becauetheavailable profilesaredominated byrelatively strong,andasyetuncorrected effectsofdiurnalvariation. Themagnetichighcanberecognized fromprofiletoprofile,however.Thegravityanomalyismostpronounced westofSanFrancisco andPt.Reyeswherethemagneticanomalyisleastdeveloped. Theridgeasstructurally defineddoesnotrepresent simplythesurfaceexpression ofgraniticbasement. Forexample,lineN23(Fig.10)showsgraniticrockbetweentwofaultsontheuppercontinental slope.Therestoftheridgeinthisprofileisunderlain byupliftedsediments ofMioceneandyoungerage,'ndUpperCretaceous sedimentary rocks,whichprobablyappearasacousticbasementinourreflection

profiles, cropoutnorthofAnoNuevowheretheridgeappearstointorsect thecoast.EastofthisridgetheBodegabasinlocallycontainsmorethan2kmoflateCenozoicsediment.

Theeastmarginofthebasinisformedbyhighanglereversefaults,fromthePt.ReyesfaultonthenorthtoanarrowfaultzoneoffHalfMoonBay.ProfilesK44andK66(Fig.11)showaburiedunconformity, belowwhichsediments arofaultedandmoretightlyfoldedthanthepostuncon-formitystrata.Comparing ourprofileswiththeH-Gdrillingages, theunconformity ismiddleMiocene.AnH-Gcrosssectionsouthwest fromBodegaHeadshowsthin'lowertomiddleMiocenestrataoverthecentralpartofthebasinwithwestwardthickening.Thisstructure indicates thatthecentralpartofBodegabasinstoodhighinthelowerandmiddleMiocene.Upliftofthewesternmargin(theFarallonridge)andsubsidence ofthebasin.commenced inaboutthelatemiddleMiocene.TheSantaCruzhighliesoffSantaCruzandsouthwest oftheFarallonridge,andbetweenthetworidgesliesOuterSantaCruzbasin(Fig.2).BoththeSantaCruzhighandouterbasinplungenorthwest (linesSl-3,Fig.12).Tothenorththehighdiminishes andthewesternmarginofthebasinisformedbyPioneerandGuideseamounts. Adredgehaulandcore(AD21andACDll}recovered maficvolcanicrockfromtheSantaCruzhigh.OuterSantaCruzbasinattainsathickness ofatleast3km.Thelowerlayersonthewestsideofthebasinaregentlyup-turnedagainsttheSantaCruzhighinlineS2(Fig.12),buttheAupper1kmofsectionabutstheridgewithnosignofdistortion. ProbablynoverticalmovementoftheridgehasoccurredinQuaternary orlatePliocenetime,basedonestimated sedimentagesinseismicprofiles, butearlierupliftisindicated. Theeasternmarginof,thebasinappearsfaultcontrolled (seelinesK68,K93,andS1-4)butfaultingaffectsonlythedeeperlayersandprobablyhasnotbeenactivesincelateMiocenetime.Thisstructure con-trastswiththebasinedgefaultsboundingBodega,SantaMariaandSurbasins,whichshowPleistocene andinsomecasesHolocene'ctivity. Dredgingonthecontinental slopewestofFarallonridgehasyieldedrockandsedimentof.Mioceneandyoungerage(Hanna,1952;UchupiandEmery,1963;CurrayandSilver,1971;SilverandMcCulloch, 1973,unpublished data)..Reflection profiles(Kl,K44,Fig.11)showMioceneandyoungerstratapassingsmoothlyacrossthecontinental slopeoutontotheabyssalplain.Thesediments arecutbysubmarine canyons,valleysandslumps,butshowlittleornosignoftectonicactivity. Insomeprofiles(Kl,K44,K66),coherentreflections belowtheyounger,regularly beddedsedimentblanketmaydenoteafoldedsedimentary sequencerepresenting atectonicenvironment quitedifferent fromthepresentone.Someofthesedeep,irregular reflections areasso-ciatedwithvolcanicrocks(K93,Sl,S3),asinterpreted frommarinemagneticanomalies. Atwater(1970)suggested thatinearlyTertiarytimetheCentralCaliforniaareawasaregionofcrustalsubduction. Wesuggestthatthefoldedsedimentary sequenceseenonthecontinental slopeinlinesKl,K44,K66,W19,andlines'L-18toL28wasdeformedbysubduction andsediment. offscraping intheearlyTertiaryepisode.Subduction appearstohaveceasedbeforeMiocenetimebecauseMioceneandyoungerstrataarenotdeformed. Pt.ReyestoCapeMendocino HorthofPt.ReyestheBodegabasinisboundedonthewestbytheFarallonridge,whichisfaultedinthisregion,andontheeastbythePt.Reyesfault.ThePt.Reyesfaultappearsasasharpflexureintheseismicprofiles(seelineW23,Fig.10) andH-Gmapitasaneast-dipping reversefault.TheBodegabasininthisarearesembles theSantaMariabasinoffshoreinthatbotharebounde'dbydown-to-basin faults.AswiththeSantaMariabasin,theBodegaandOuterSantaCruzbasinsoriginated inlatemiddleMiocenetime(H-G).Bo<<gabasinnarrowsnorthward astheFarallonridgeapproaches thecoast.Threeacousticunitscanbedistinguished, withinBodegabasinwhichareseparated bybasin-edge unconformities (profileW23,Fig.10).Thelowermost unitismost.deformedandisprobablyupperMiocene,basedonsectionsbyH-G.Thereflectors withinthisunitareparallel, demonstrating thatupliftofthe'basinmarginsorrelativesubsidence ofthebasinbeganinlatestMioceneorearlyPliocene. Theoverlying Plio-Pleistocene bedsarelessdeformedandtheuppermost layershowsnoevidenceoftiltingagainsttheridge.Approximately twokilometers ofPlioceneverticalrelativeupliftareindicated fortheFarallonridge~GraniticrockscropoutasfarnorthasBodegaHeadwithintheSalinianblock.NograniticbasementisreportednorthofBodegawestoftheSanAndreasfault,buttheextentoftheFarallonridgemayindicatesuchbasementasfarnorthasPointArena.Theridgeappearsasablock-like upliftinprofilesKlandK3(Fig.11),andinW19throughW26(Fig.10).FaultsboundoneorbothsidesoftheridgeintheseprofilesandstrataofthewestsideofBodegabasinareuplifted. InlinesW18,W17andN16,anunconformity truncates boththeridgeandthebasinstrata,andPleistocene depositsprogradeacrossit.The ~~~~blockstructure oftheridgeisnotevidentintheseprofilesandtheuppersurfaceoftheridgeisnotahardreflector, asitisfarthersouth.Thus,theridgestructure extendsasfarnorthasPointArena,butgran'itic basementisfollowedwithconfidence onlytoapproximately 38'30'N,or50kmsouthofPointArena.Itremainsuncertain, therefore, whethergraniticrockscontinueatdepthundertheridgetoPointArenaorar'Tabsentnorthof38'30'Nandsedimentary rocksmakeupthebodyoftheridge.Evidencesuggestive ofoffshoregraniticbasementnorthofBodegawaspresented byWentworth (1968)intheGualalaareawhereheidentified coarseclasticCretaceous sediments derivedfromthesouthwest. SuchrocksunderthenorthernpartoftheFarallonridgecouldprovidesuchasource.TheseaflooroffPointArenaisexceptionally complex.The,Farallon ridgeendsoffshoreofthepoint,butitsnorthernterminusisnotwelldefined.TheSanAndreasfaultbendstoamorenortherly trendnorthofPointArena,andnorthwest ofthepoint'isaseriesofcomplexnorthwest trendingfoldsandfaults(Fig.3)inlateCenozoicstrata.Thesestr'ataarepartofthePointArenabasinofH-G.Onthewestsideofthebasinabroad,lowstructural ridge,theOconostota ridgeincreases inwidthnorthward. TheridgeisIseenunderlying abroad,lowterracenearthebaseofthecon-tinentalslope(Fig.10).'ineWX(Fig.13)followstheridgecrestandshowstheirrcgular complexstructure oftheridgeunderlying thefairlyuniformlayeringoflateCenozoicstrataabove. The,basementrockofOconostota ridgecropsoutonthenorthflankofNoyoCanyon(Pig.10,lineW8)andadredgehaulatthislocationyieldedabundantgraywacke. Therockisweaklyfoliatedtohighlyshearedinthinsectionandshowschloritealteration ofthegroundmas.Itispoorly'fossiliferous butcontains"afewnon-diagnostic Mid-Eocene toOligocene nanno-fossils"(T.R.Worsely,writtencommun.,1973).Site173ofleg18oftheDeepSeaDrillingProject(DSDP)wasdrilledonthewesternflankoftheridge.Thehole'pene-tratedacompletesectionofmarinestratafromPleistocene throughlowerMioceneorupperOligocene(?) andterminated inandesite(culm,vonHueneandothers,1973).Thereflection profilesshowthattheseMioceneandyoungerstratapasssmoothlyacrossthebaseofthecontinental slopeanddrillingindicates thatdepositional conditions werequietinthisareabacktotheearlyMiocene.RecoveryofdeformedearlyTertiarysedimentary rockandofandesitefromOconostota ridgedemonstrates someof'thelithologic complexity oftheridge.InlineW18(Fig.10)thewestflankofOconostota ridgenearthebaseoftheslopeabutstheacoustic'-basement reflector beneaththesediments westoftheridgeandsuggeststhatthecontactbetweenpre-Miocene continental slopematerialandtheoceaniccrustwastectonic. Theseobservations implythattheOconostota ridgewasformedundertectonicconditions 'thathavenotbeenactivesincetheearlyMiocene.J-20 'ThePointArenabasinasdescribed byH-G,isboundedbytheSanAndroasfaultontheeast,PointArenatothesouth,theMendocino faulttothenorth,butisilldefinedonitswcternmargin.>leconsidertheOconostota ridgetoformthewesternmargin.Thestructure ofthisbasinchangesmarkedlyfromsouth'henorth.profileN13(Fig.10)offPointArenahowsasectionofdeQrmeddepositsofprobableMioceneagecoveringmuchofthe;...rgin.Thismaterialisoverlainuncon-formablyintheheifadupperslopeareabyprograding latestCenozoicdeposits. U.-,dertheshelftheunconformity dipsuniformly eastwardtolocation-whereitappearstoterminate against,afaultwithsignifica."." verticaloffset-ZnlineNllfol=-=Miocenerocksaretruncated byanunconformitywhichisin--.folded.'I(Fig.10,lineNll,'o20km)Beneaththeshelfedgeis,abasinwiththickdepositsabovethemityH-Gr:=-==aultswith.severalkilometers ofverticaloffs<<oneithersid=--=thisbasin.ThebasinisseenonprofilesN9th'roughN12.The-=~logyeastofthebasiniscomplexandob<<redbymultiple--=lections ontheseismicrecords.Theupporunconformity p'==avewidespread extentthroughout theeastern<<geofthe'==-==~andcropsoutorsubcropsatdepthsbetweenoneandtwo.'c=-..eterbelowsealevel.Xfthisinconformit resul<<dfromerosio-.=-;waveaction,uptotwokilometers ofsubsidence su~~<<nceoftheea~==->marginofpoint~renabasinmaybeinferredforguatern=- -.-"ime.~"ottomreflee---sareapproximately paralleltotheeeaa"<<fOconos---=ridgeandminorfaulting(lineN8,Fig.10) occurs.Profilesfarthernorth,WlthroughW7,showminor'.deformation oflateCenozoicdepositsbutolderrocksareintern-allydeformed(lineNX,Fig.13).Thesurfaceoftheolderrocksisirregular, andunliketheyoungersediment, shownoobviousrelationtoerosional channeling. Anumberofrelatively tightfoldsandassociated faultsItrendnorthwest fromPointArenaanddieoutapproximately 50kmtothenorth,wherethecontinental slopebecomesmoregentle.'majorpartofthedeformation inthisarea,including thelargeshelf-edge basin,thefoldedunconformity, andfaultsoflargeverticaloffset,aremost,likelycontrolled-bytectonicprocesses, althoughsomedeformation mayberelatedtodownslope movementofsedimentundertheinfluence ofgravity.TheSanAndreasFaultZoneTheSanAndreasfaultchangesorientation northofPointArenatoa'orenortherly-trend andcanbetracedonshorejustsouthofPointDelgada(CurrayandMason,1967).SouthofShelterCovesixprofiles(4notshowninFig.1)crosstheSanAndreas,whichoffsetstheseafloorwiththewestsideup,producing ashoreward facingscarp.Anotherfault,twomileseasthasnoseaflooroffset.ThemaximumobservedverticaloffsetontheSanAndreasfaultscarpoff-shoreis8m,andthereliefdecreases southward. Thegeneraldisplacement historyoftheSanAndreasisrightlateralslip,andsuchmovementwouldhaveproducedeast-side-up offsetsincetheseafloorslopessouthward alongthestrikeofthefault.Therefore theobservedwest-side-up topographic offsetmustbeduetoverticalmovement. J-22 23'NorthofPointDelgadathelocationandcharacter oftheSanAndreasisunknown.' Nason(1968)mappedanumberofshearzoneson,landbetweenPointDelgadaandCapeMendocino buthecouldfindnoevidenceforrecentmovementonthezone"nearPointDelgata.Un-fortunately, thecleargeomorphic evidencefor1906faultingatPt.Delgadacannotbetracedacrossthisarea(Lawson,1908).Thislackofevidencemaybetheresultofobliteration ofsuchevidencebyextensive landsliding andmasssoilmovementthatoccurinthisarea;orperhaps,theSanAndreasdoesnotextendonshorenorthofPointrDelgadaasawell-defined fault.Xnthisregard,BeutnerandHansen(1975)carefully examinedthestructure ofthelargeinlandshearzonesanddetermined aleft..lateral senseofshearing, associated withlateTertiarysubduction. Theyalsofound,however,thatNN-trendingstructures justalongthecoastline showedevidenceforrightlateralshear.Detailedreflection surveysthatwehavemadeoffshorebetweenPointDelgadaandCapeMendocino (notshowninFig.1)havenodis-covereddefiniteevidenceoffaultingoffshorebetweenCapeMendocino andPointDelgado.Numerousacoustic'irregularities onthenearshore profilesmayrepresent

faulting, butthedeeperstructure isobscuredbymultiplereflections.

Noneoftheseirregularities canbetracedbetweenprofiles. ZftheSanAndreasfaultisexpressed byasingletracenorthofPointDelgadaitmayrunalongthebeach.Seeberandothers(1970)showaverycomplexpatternofmicxoseismic activityinthisregion.Thenorthward bendoftheSanAndroaspresentsaninteresting geometrical puzzle.Afault-fault-trench triplejunctionliketheJ-23 24I~Mendocino isunstableunlessonefaultisonastraightlinewiththetrench(subduction zone)(Fig.14).TheMendocino shouldbeunstablebecausetheSanAndreasfaultandthesubduction zonearenotaligned.However,northofPointArenatheSanAndreasbendsnorthward andthen,atPointDelgada,northwestward. Thisbendingraisesaseriousprobleminthatthenortherly trend,betweenPointArenaandPointDelgada,shouldbeassociated withextension acrossthe.fault,asindicated inFigure14d..Possiblysubsidence ofthecontinental margininthisarea,asseenbydeepunconformities, agentlecontinental slope,andanarrowshelfisamanifestation ofextension. However,insteadofchangingthegeometryofthetriplejunctiontoacquireanewstability configuration (asin14c),theplateboundaries. appearto1beadjusting tomaintainstability oftheoldergeo'metry. TECTONXCDEVELOPMENT OFTHECONTINENTAL MARGINThestrueturaldevelopment ofthecontinental marginofCentralCalifornia providesimportant: constraints forany.scenarioofthetectonicevolution ofthewesternUnitedStates.Thestructure ofthelowerpartofthecontinental slopeinthisregionshowswelllayeredMioceneandyounger'trata smoothlycoveringanirregular, hummocky"basement" thatisatleastinpart,composedofdeformedPaleogene sedimentary andvolcanicrocks.Thisstructural superposition isinterpreted toindicatePaleogene deformation, probablyrelatedtosubduction oftheFarallonplate(Atwater, 1970),followedbyMiocenetoHolocene i~g~~rCtectonicquiescence alongthelowerpartofthecontinental slope,EvidenceforMioceneandyoungerquiescence isprovidedbythepresenceofavolcanicridgealonganearlyPliocenetransform fault(Fig.3)thatextendsundeformed fromtheoceaniccrustontothecontinental slopewestofSantaLuciabank.Becausetheridgeshowsnooffetatitsjunctionwiththeslope,nosignificant Mioceneoryoungershearcanhaveoccurredonthelowerpartoftheslopeifthiscorrelation iscorrect.Incontrast, abundantevidenceisseenforextensive

faulting, bothhorizontal andvertical, alongthecentralandinnerpartsofthecontinental margin.Animportant structural featurefordeciphering tectonicmovements inthisregionistheFaxallonridge.Thegraniticintrusives alongtheoffshoreridgeindicatethatitistheprobableoffshoreextension oftheSalinianblock,thesliverofgraniticandmetamorphic basementlyingbetweentheSanAndreasandSur-Nacimiento faultzones(Page,1970).TheSalinianblockisgenerally interpreted asasliceofSierran-type basementthathasbeendisplaced northwestward'long theSanAndreasfaultsystem(Efamilton, 1969;Page,1970;Crowell,19G2)althoughalternative hypotheses havebeensuggested (kIsu,1971).Ifthefirsthypothesis iscorrect,thenthenorthernextentofgraniticbasementrocksrecordsthetotalhorizontal offsetalongtheSanAndreasfaultsystem.Fromthenorthernmost extentofrecognizable graniticbasementwestofthefaulttoitsnorthernmost extenteastofthefault,theminimumslipappearstobe550km,andfromthenorthernextentofFarallonridge 26kmorphology themaximumslipis600km(Pig.2a)(Silverandothers,1971).Atotaloffset,of550to600kmalongtheSanAndreasfaultwasfirstsuggested byNentworth (1968)andhisevidencewasfurthersubstantiated byRoss(1972),basedonidentifying offsetsourceterranesforconglomerates withintheGualalabasin.Howandwhenthisoffsetoccurredisonlypartlyresolved.

Rightslipdisplacement of300kmpost22m.y.a.hasbeendocu-mentedonthecentralpart.oftheSanAndreasfaultbetweenSanFrancisco andtheTransverse Ranges(Huffman, 1972;Matthews, 1976)andNilsenandClarke(1975)documented nooffset,onthatsegmentfrom45to22m.y.a.Xtisimportant. todistinguish overwhatsegmentstheoffsetsapply,becausetheavailable information canbeexplained inseveralways.Oneisatwo-stage, singlefaultmodel(Suppe,1970)givingabout300kmoflateCretaceous toearlyTertiaryoffsetontheSanAndreasfault,followedbyasecond,Mioceneandyoungeroffset,ofanother300kmonthefault..Asecondmodelisasinglestage-multifault historyinwhichgreateroffsetscanoccuronthenorthernmost segmentoftheSanAndreasthanfarthersouthduetosliponother,subparallel faultswestoftheSanAndreas.TherecentstudiesoftheSanGregorio-Hosgri faultzoneindicating 100+15kmofright.-lateral offset.supportthemulti-faultmodel,althoughtheoffsetmappedtodateisinsufficient toproveasinglestagehistory.Graham(1976)mappedamaximumof35kmrightslipontheRinconada faultbringingthemaximum documented Miocene.and youngeroffsetontheSanAndreasfault~sstemtoapproximately 450km.ActivityontheSanGregoriofaultmay'playamajorroleinpartitioning strainbuildupintheCentralCalifornia region.Studiesoflateraloffsetoffences,roads,railroads andotherlinearmarkersaftertheSanFrancisco earthquake of1906showedcommonevidenceforoffsetsof5m(16ft)ormorenorthofSanFrancisco, butonly21/2to3m(8to10ft)southofSanFrancisco (Lawson,1908).Oneexplanation ofthisdifference isalesserstrainbuildupontheSanAndreastothesouthbecauseofslipontheSanGregoriofault.TheHayward-Calaveras faultzonesmayalsorelievestrainbuildupontheSanAndreassystem,butitisnotclearwhysliponthisfaultzoneshouldselectively partition thestraindifferently northandsouthofSanFrancisco (seeFig.3).Theremaining 100(+)kmofbasementoffsetmaybeexplained byMioceneandyoungerundiscovered slipalongotherfaultscuttingtheSalinianblock.Theirdiscovery wouldprove.theJohnson-Normarkhypothesis. Alternatively, approximately 100kmoflateCretaceous toearlyPaleocene offsetmayhaveoccurredontheSanAndreasfault,assuggested bySilverandothers(1971)toexplainthedevelopment oftheGualalabasininlatestCretaceous time.Theyproposedarhombochasm openingofanelongatebasintoexplainthebasaltflooredbasinfilledwith.verythick,coarseelasticsediments (Nentworth, 1968).AnearlyTertiarySanAndreasfaultisalsofavoredbyNilsenandClarke(1975)toexplainearlyTertiarypaleogeography andbasindevelopment in 28~W~CentralCalifornia. Development oftheBasinsTheresultsofdrillinginthebasinswhichsuggestanearlysynchronous originofthecentralCalifornia basinsinmiddletolatemiddleMiocenetime(roughly10to14m.y.a.),placetightconstraints onhypotheses fortheoriginofthebasins.Forexample,anoriginrelatedtoasouthward migrating tripleVjunctionmustbeeliminated. herebecausethetimingofthismigra-tionwasoveraperiod8to10m.y;longfromabout29to20m.y.a.inthisregion.Theagedatagivenoindication ofanageprogression intheoriginofthesebasinsandthetiming(10-14'm.y.'vs.29to20m.y.)isbetween6and'20m.'y.toolateforthismodel.Thispaperdoesnotdealwiththedevelopment ofthesouthernCalifornia Borderland basins,butmostofthemapparently developed inaboutthemiddleMiocene(10to15m.y.a.)(Blakeandothers,1978).According toAtwater,(1970)themigrating triplejunctionwasinthevicinityoftheBorderland inmiddle.Miocenetimeaswell.ThusthesouthernCalifornia Borderland, whilemuchmoreimpressive inbasindevelopment thancentralCalifornia, doesnotoffertheopportunity todistinguish betweenamigrating triplejunctionvsamechanism involving nearsynchronous development ofCalifornia offshorebasins.~Toinvestigate thepossibility ofachangeinplatemotionsbeingresponsible forthenearsynchronous development ofthebasinswereconstructed thehistoryofPacific-. AmericamotioninmuchthesamewayasAtwaterandhiolnar(1973),andthencomputedaverageJ-28 ~,~movementvectorsat36'N,121N,and33N,119Mfortheintervals 0-4.5,4.5-10,10-21,21-29,and29-3Sm.y.TheresultsareshowninTable1.Rotations weredoneinareference framefixedtoNorthAmericaandinarestorative sensefortheglobalcircuitPacific-Antarctic-Indian-African-North Americanplates.DatasourcesaregiveninTablel.ThethorolargestsourcesoferrorareinthecentralIndianOcean(Ind-Afr) andthecentralAtlanticOcean(Afr-NAm)becausetheserotations require'thegreatestamountofdatainterpolation ofseafloormagneticanomalies. Tectonichind-.castingofthissort.canbeimprovedupononlybymoredetailinthoseregions.Inadditiontotheaccelerated rateofmovementinthelateCenozoicisthesignificant changeofazimuth,especially after21m.y.a.,'orsubsequent tothechangealongthiscontinental marginfromsubduction totransform motion.At36N,theazimuthis339'or21-10m.y.,328'ox4.5-10m.y.,and321~for0-4.5m.y.'I4Thesesuccessively morewesterly-directed movements ofthePacificrelativetotheNorthAmericanplatemayhaveproducedextensional strainalongthecontinental margin,perhapsculminating inthe-middleMiocene,about10-14m.y.a.Theextensional, strainwasmanifested intheformation ofthebasinsalongtheCentralCalifornia margin,andperhapsthoseofthesouthernCalifornia borderland aswell.Sincethevectorsarecomputedfromfiniterotationpolestheyrepresent anaveragevalueforthetimeperiod,butnotnecessarily theactualdirection atanyspecifictime.IfitwerepossibletoJ-29 30\'qi~computerotationpolesforsmalltimeintervals wemightdiscoverthatthepoleofrotationbetweenthePacificandNorthAmericanplateshasbeenchangingcontinually duringthelast30m.y.Suchsmallbutcontinual changesindirection andrateofplatemove-mentsmayresultinthedevelopment ofa,complex structural geometryintheareaoftheplateboundary, asobservedalongCentralCalifornia continental margin,andinfact,alongthe/entirewesternmarginoftheUnitedStates.CONCLUSIONS Marinegeological andgeophysical observations supportthegeneralmodelofAtwater(1970)ofearlyTertiarysubduction \followedbyNeogenetranslational shearalongtheCentralCalifornia continental margin.EarlyTertiaryrocksformirregular structural I,surfacesandshowrelative1y intensedeformation. Neogenestrataarewelllayered,mildlywarpedandcutbyhighanglefaults.LargeshelfbasinsformedalongthemargininlatemiddleMiocenetime,probablyfromacomponent ofextensional strainduringplatetranslational movements. Platetectonicanalysisusingfiniterotations aroundaglobalcircuit:Pac-Ant-Ind-Afr-NAM, showsachangeinaveragePac-NAMmovementduringaboutmiddleMiocenetoamoreextensional senseofshear.Thischangecouldberesponsible forthesynchronous openingofthebasins.Thisanalysisshowsa8changeinpoleofrelativemovementforeachinterval, andsuggeststhatinstantaneous movementbetweenthePacificandNorthAmericanplatesmayhavechangedcontinually overthepast30m.y.1 31Studyofthecontinental marginprovidesconstraints onthc-offsethistoryoftheSanAndreasfaultsystem.Thenorthward extentofgr'anitic basementoftheSalinianblock,astracedbytheFarallonridge,limitsbasementoffsettobetween550and600km.Ofthisfigure,300kmoccurredontheSanAndreasfaultinNeogenetimebetweenSanFrancisco andtheTransverse ridgesandupto150kmontheSanGregorio-Hosgri faultandtheRinconada faultsouthofSanFrancisco. ThesevaluesaddtotheSanAndreasoffsetnorthofSanFrancisco. EarlyTertiarypaleogeographic andprovenance studiesbyNilsenandClarke(1975),aswellasthedifference betweenmeasuredfaultslipandbasementoffsetarebestexplained ifsomeoffsetonfaultswithintheSalinianblockoccurredduringlatestCretaceous toPaleocene time.Thusatwo-stage, multifault modelforSalinianoffsetispreferred,. withabout100kmslipinlatestCretaceous toPaleocene andabout450kmpost-22m.y.,Granitic bouldersdredgedfromSantaLuciabankhavetwopossibleorigins.Xftheboulderswerelocallyderived,.granitic faultsliversmustoccurwestoftheSalinianblockandthesimpleoffsetmodelpresently acceptedbymanyCalifornia geologists mustberevised.Alternatively, thebouldersmayhavebeentransported 100kmormorefromsourceareasintheSalinianblock. ~.'C~ITable1.Pacific-North AmericaFiniteMotions*36~N,121O'33'N,119WTimeIntervalm.y.RateAzimuth(1)(cm/yr)Azimuth(1)Hate(cm/yr)(2)4.5-0(3)10-4.5(4)21.2-10(4)29.2-21.2(4)38-29.232132833932'13205.64.53.23.81.73193263353193185.64.63.13.91.8*Summation ofthecircuit:Pacific-Antarctic-Xndian-Af rican-NorthAmericanplates.(1)Degreespositiveclockwise from.north.(2)Allrotations fromMinsterandothers(1974).'II(3)Pac-Antfrom,Molnarandothers(1975).AllothersfromMinsterandothers(1974).(4)Pac-Ant:Molnarandothers(1975).Ant-Xnd:WeisselandoQ>ers(1972).Xnd-Afr:McKenzieand,Sclater (1971).Afr-NAm:,PitmanandTalwani(1972). I~~32REFERENCES CITEDAtwater,T.M.,1970,Implications ofplatetectonics fortheCenozoictectonicevolution ofwesternNorthAmerica:Geol.Soc.AmericaBull.,v.81,p.3513-3536. Atwater,T.M.andMolnar,P.,1973,RelativemotionofthePacificandNorthAmericanplatesdeducedfromseafloorspreading intheAtlantic, IndianandSouthPacificoceans:Kovach,R.L.andNur,A.,eds.,StanfordUniversity Publica-tionsinGeol.Sciences, v.13,p.136-148.Bailey,E.H.,Irwin,W.P.,andJones,D.L.,1964,Franciscan andrelatedrocks,andtheirsignificance inthegeologyofwesternCalifornia: Calif.Div.ofMinesandGeologyBull.183,177p.Beutner,E.C.andHansen,E.,1975,Structural evidenceofplateinteractions fromcontinental rocks,CapeMendocino toShelterCove,California(abs.):Geol.Soc.Amer.Abs.withPrograms, v.7,no.7,p.997.Blake,M.C.,Jr.,Campbell, R.H.,Dibblee,T.W.,Jr.,Howell,D.G.,Nilsen,T.H.,Normark,W.R.,Vedder,J.G.,andSilver,E.A.,1978,Neogenebasinformation andhydrocarbon accumulation inrelationtotheplatetectonicevolution oftheSanAndreasfaultsystem,California: Am.Assoc.Petroleum Geol.Bull.(inpxess).Buchanan-Banks, J.M.,Pampeyan, E.H.,Wagner,H.C.,andMcCulloch, D.S.,1978,Preliminary mapshowingrecencyoffaultingincoastalsouth-central California: ,U.S.Geol.SurveyMisc.FieldStudiesMapMF-910,3mapsat1:250,000. Byerly,P.,1930,TheCalifornia earthquake ofNovember4,1927:Seismol.Soc.AmericaBull.,v.20,p.S3-66.Crowell,J.C.,1962,Displacement alongth'eSanAndreasfault;California:Geol.Soc.AmericaSpec.Paper71,61p.Curray,J.R.andNason,R.D.,1967,TheSanAndreasfaultnorthofPointArena,California: Geol.Soc.AmericaBull.,v.78,p.413-418.Curray,J.R.,andSilver,E.A.,1971,Structure ofthecontinental marginanddistribution ofbasementrocktypesofcentralCalifornia (abs.):Geol.Soc.Amer.Abs.withPrograms, v.3,no.2,p.106-107.Gawthrop, W.H.,1977,Seismicity ofcentralcoastalCalifornia (abs):Geol.Soc.AmericaAbs.withPrograms, v.9,no.4,p.422.Graham,S.A.,1976,.Tertiarysedimentary tectonics ofthecentralSalinianblockofCalifornia: Ph.D.thesis,StanfordUniv.,510p.Graham,S.A.andDickinson, W.R.,1978,Evidencefor115kmofrightslipontheSanGregorio-Hosgri faulttrend:Science,v.199,p.179-181.Greene,H.G.,1970,GeologyofsouthernMontereyBayanditsrelationship tothegroundwaterbasinandsaltwaterintrusion: U.S.Geol.Surveyopenfilereport,50p.Greene,H.G.,Lee,W.H.K.',NcCulloch, 'D.S.andBrabb,E.E.,II1973,Faultsandearthquakes intheh1onteroy Bayregion,California: hiisc.FieldStudiesllapNP-518.J-34 ~~Hamilton, N.,1969,MesozoicCalifornia andtheunderflow ofPacificmantle:Geol.Soc.AmericaBull.,v.80,p.2409-2430. FFall,C.A.,Jr.,1975,SanSimeon-EJosgri faultsystem,coastalCalifornia: economicandenvironmental implications: Science,-v.190,p.1291-1294. Hanna,G.D.,1952,Geologyofthecontinental slopeoffcentralCalifornia: Calif.Acad.Sci.Proc.,FourthSer.,v.27,p.325-358.Hopson,C.A.,Frano,C.J.,Pessagno, E.,andMattinson, J.M.,1973,LateJurassicophiolite atPointSal,SantaBarbaraCounty,California (abs):Geol.Soc.AmericaAbs.withPrograms, v.5,no.1,p.58.Hoskins,E.G.andGriffiths, J.R.,1971,FFydrocarbon potential ofnorthernandcentralCalifornia offhore:Am.Assoc.Petroleum Geol.Mem.15,v.1,p.212-'228. Hsu,K.J.,1971,Francicanmelangesas.amodelforeugeo-synclinal sedimentation-andunderthrusting tectonics: Jour.Geophys.Res.,v.76,p.1162-1170. Huffman,0.F.,1972,Lateraldisplacement ofupperMiocenerocksandtheNeogenehistoryofoffsetalongtheSanAndreasfaultincentralCalifornia: Geol.Soc.AmericaBull.,v.83,p.2913-2946. Johnon,J.D.,andNormark,N.R.,1974,Neogenetectonicevolu-tionoftheSalinianblock,west-central California: Geology,v.2,p.11-14.Kulm,L.D.,vonHuene,R.,andothers,1973,InitialReportsoftheDeepSeaDrillingProject,v.18,1077p.J-35 ~~Lawson,A.C.,1908,TheCalifornia earthquake ofApril18,1906:ReportoftheStateEarthquake Investigation Commission, v.1,451p.Martin,B.D.andEmery,K.O.(1967,GeologyofMontereyCanyon,California:Am.Assoc.Petroleum Geologists Bull.,v51(p22812304~Matthews, V.,XXX,1976,Correlation ofPinnacles andNeenachvolcanicformations andtheirbearingontheSanAndreasfaultproblem:Am.Assoc.Petroleum Geologists Bull.,v.60,p.2128-2141. 'McCulloch, D.S.,Clarke,S.H.,Jr.,Field,M.E.,Scott,E.N.,andUtter,P.M.,1977,Asummaryreportontheregionalgeology,petroleum potential, andenvironmental geologyofthesouthernproposedleasesale53,centralandnorthernCalifornia outercontinental shelf:U.S.Geological SurveyOpenFileRept.77-593,56p.McKenzie, D.P.andMorgan,N.J.,1969,Theevolution oftriplejunctions: Nature,v.224,p.125-133.McKenzie, D.P.andSclater,J.G.,1971,Theevolution oftheXndianOceansincethelateCretaceous: Geophys.Jour.Roy.Astro.Soc.,v.25(p437528.Minster,J.B.,Jordan,T.H.,Molnar,P.,andHaines,E.,1974,Numerical modelingofinstantaneous platetectonics: Geophys.Jour.Roy.Astro.Soc.,v.36,p.541-576.J-36 Molnar,P.,Atwater,T.M.,Mammerickx, J.,andSmith,S.M.I'I1975,Magnoticanomalies, bathymetry, 'andthetectonicevolu-tionoftheSouthPacificsincethelateCretaceous: Geophys.Jour.Roy.Astro.Soc.,v.40,p.383-420.Nason,R.D.,1968,GeologyofCapeMendocino, Dickinson, N.R.andGrantz,A.,eds.,StanfordUniversity Publications inGeol.Sciences, v.11,p.231-34.Nilson,T.H.andClarke,S.H.,Jr.,1975,Sedimentation andtectonics intheearlyTertiarycontinental borderland ofcentralCalifornia: U.S.Geol.SurveyProf.Paper925,64p.Page,B.M.,1970,Sur-Nacimiento faultzoneinCalifornia: Continental margintectonics: p.667-690.Geol.Soc.AmericaBull.,v.81IPitman,N.C.andTalwani,M.,1972,Sea-floor spreading intheNorthAtlantic: Geol.Soc.AmericaBull.,v.83,p.619-646.Ross,D.C.,1972,Petrographic andchemicalreconnaissance studyofsomegraniticandgneissicrocksneartheSanAndreas-faultfromBodegaHeadtoCajonPass,California: U.S.Geol.SurveyProf.Paper698,92p.Seeber,L.,Barazangi, M.,andNowroozi, A.A.,1970,Micro-'arthquake seismicity andtectonics ofcoastalnorthernCalifornia: Seismol.Soc.AmericaBull.,v.60,p.1669-1699. Silver,E.A.,1974,Structural interpretation fromfree-air/gravityontheCalifornia continental margin,35'o40'N(abs):Geol.Soc.AmericaAbs.withPrograms, v.6,no.3,p.253.J-37 Silver,E.A.,Curray,J.R.,andCooper,A.K.,1971,Tectonicdevelopment ofthecontinental marginoffcentralCalifornia: .inLipps,J.andMoores,E.M.,eds.,GeologicguidetothenorthernCoastRanges-Point Reyesregion,California: Guide-book,Geol.Soc.Sacramento Ann.FieldTrip,p.1-10.ISuppe,J.,1970,OffsetofLateMesozoicbasementterranesbytheISanAndreasfaultsystern:Geol.Soc.AmericaBull.,v.81,p.3253-3258. Uchupi,E.andEmery,K.O.,1963,Thecontinental slopebetweenSanFrancisco, Californi'a, andCedrosXs.,Mexico:Deep-SeaRes.,v.10,p.397-447.Nagner,H.C.,1974,MarinegeologybetweenCapeSanMartinandPt.Sal,south-central California offshore: U.S.Geol.SurveyOpenFileReport74-252,17p.Neissel,J.K.andHayes,D.E.,1972,Magneticanomalies intheSoutheast XndianOcean:Antarctic Oceanology XX:TheAustralian-New Zealandsector,Hayes,D.E.,ed.,AmericanGeophysical Union,Nashington, D.C.,p.165-196.Nentworth, C.M.,1968,UpperCretaceous andlowerTertiarystratanearGualala,California, andinferredlargerightslipontheSanAndreasfault:inDickinson, N.R.andGrantz,A.,eds.,Proc.Conf.Geol.ProblemsoftheSanAndreasfaultsystem:StanfordUniv.Publications inGeol.Sciences, v.11,p.130-143.'oodring, N.P.andBramlette iMNi1950,Geologyandpaleontology oftheSantaMariadistrict, California: U.S.Geol.SurveyProf.Paper222,185p.J-38 FIGURECAPTIONSFigurel.Trackofgeophysical cruisesandgeologicsampleloca-tionsonthecentralCalifornia continental margin.Heavylinesareseismicprofilesillustratedin thispaper.Identification ofseismicprofilesbycruise:W=ThomasWahingtonK=KelezS=Bartlett1972,leg1.L=Bartlett1972,leg2LDM=DavisprofileIdentification ofsamplesbycruise:D=KelezDredgeF=KelezDartCoresADC=Melville(Antipode) DartCoreAD=Melville(Antipode) Dredge7DS=ThomasWashington DartCore(7Tow)B=BartlettDredgeFigure2.Mapofstructural featuresonthecentralCalifornia continental margin.Locationofridges,basinsandmajorfaults.CM:CapeMendocino; PA:PointArena;PR:PointReyes;SF:SanFrancisco; M:Monterey; SS:SanSimeon;PS:PointSal;PC:Point.Conception. Figure3.Mapoffaultsandfoldsonthecontinental margin.Figure4.Linedrawinginterpretation ofBartlettseismicreflection profilesL16toL20acrosstheSantaMariabasin.J-39 Figure5.Linedrawinginterpretation ofBartlettseismicreflec-tionprofilesL2toL14acrosstheSurandSantaMariabasin.Figure6.Free-airgravitymapofthecontinental margin,from35'o40'North. Contoured fromNationalOceanSuryeyunpublished data.Contourinterval10mgal.Figure7.Residualmagneticmapofthecontinental marginandoceaniccrusttothewest.MapiscombinedNationalOceanSurveydataandBartlettdata.Figure8.Crustalmodelsatisfying observedgravityforprofileL18.2.65means2.65gm/cc.Noscaleexaggeration. Eastisontheright.Figure9.Reflection profiletakenbyD.G.MooreacrosstheISantaMariabasinshowinglocalfoldingofstrataagainsta"buttress" ofacousticbasement. LabeledLDMonFigure1.Figure10.Linedrawinginterpretation ofThomasWashington profilesW6,8,ll,12,13,16,18,19,and23.FromExpedition 7-Tow,leg9B.Figure11.Linedrawinginterpretation ofreflection profilesKl,3,44,66,68,and93,fromtheR/VKelez.Figure12.Linedrawinginterpretation of'reflection profilesSl-S4,fromleg1ofR/VBartlettin1972.ProfilescrossouterSantaCruzbasinandSantaCruzhigh.Figure13.Linedrawinginterpretation ofprofileNX,takenalong'heaxisofOconostota Ridge.J-40 ~~~Figure14.Geometryofhypothetical stableandunstablefault-fault-trench triplejunctions, predicted newcondition ofstability andgeneralized observedgeometry. a)Stablefault-fault-trench triplejunction. b)Generalized unstableformofMendocino triplejunction. c)Predicted newpositionofstability =Ridge-Ridge-Ridge .triplejunction(thissolutionisfromClementChas'e,Univ.ofMinnesota, oral,commun., 1976).d)GeneralobservedgeometryofMendocino triplejunction, illustrating bendingofSanAndreasfaultatitsnorthernend,ratherthantriplejunctionevolution, tomaintaingrossgeometric stability. KsrarSS~KILCKCTERS IOOPIti~~a0ag/Vl/x0+oaa0~4'I~Vo~+~0yeaeeVCEOKKTSICAL TRACK0OREOCCORDARTCCRCCONTOURINTERVALSOOIICTCRS ~h,a,,/pOz'JaSSA0,aaafeaSoI0K<LOUETERSOc.'1LIaa.>SSIWSSsras.SrSSiltV l23~40'22~39~l2'8'7l20'6'5~l25~GraniticridgeFranciscan ridgeBasinFault.ptl,tt'0CALASERA9 B'AV~,'qu;Anp ~t-QAiC$AV"'-"~"ANGRINGO:J,SVR.,;,;-.~hp9GRIFAV7R:0FAV'.FAPr.Arrno80$cn~z~~zr/A... -~:;;:';.*.~ZZ~BASE4~~OF~~~~~CONTINENTAL '.."-"""LOPE~+~~~~~~34~I200l2PtppKitomoters 40+39~38~l25~37~l24>>36~35l23'4~l22~ It5~50ST+SV55>>-C-XXXTAULT,NACNUNCSOHOONNTHAOWM STOCfAULTTONICAHTICLIAC 01SASS@TNT1ICCCSTNCLINC01~ATINATISVOLCAN>C1IOCCLA"<<ASNAVSAAOTAULT5AllAHOCfAULTlCCyoAII&oem+fAifatOASNIpie~IOOCO+OSTOTA SLOrCCON'5INLNSASCXILOIICT515AINCO<AOA TAU'TfAULT~0fTAULT~SAAIANOACAS~P~ALCOO~~f4'~,c.'--Nlll15(CAVCSA>>NUOA~,~SAIITATOUTIgg+~<11S0IOO554P55It5'5ITS55RiItt t40120804020Km0~0SantoLuciaBankSontoferroBasrnC./.KPSecL16/rr6aCZlalk.~~~/r20Km00<<cL1820Krn00s<<L20F~-wr+r~r+/i/~ci$:"rr~rr050020Krn00/q'r"=--.=;-'==--.=-~~.Q/ i~SecFcurt20Km0Qgr-SecL24r/MVQ~~s<<L2620Km207<<cL28SantaBankFaultV,Kp10K ~~4020,Km0SecKm200SecL40~r/Cr~p.r/rSecL620Km00scLgr20Km0pgr2riSecL.1020Km00c'20Km00scocc.scMo.pc~8KjP.220Km00ISurBasinigf/r,rrcS'rSrrrrV.E.~10K~oJ-46 I25'cc)pc1r4c123'22c4acO0O30c38cBodegaHeadI38'7~125c00SanFrancisrPt.Reyes38'-'"C'c>Pt.AnoNuevo121'7c70.p((..oo~~""..MontereyPointSurrc~~c~'-+yy38c050KMInterval10mpalFREE-AIRGRAVITY4@~~EcrcrcBay35'24c123c122c35'21'-47 4pe12S123~t122'200400I~~Qm,MQ'II0(')FTARCNAVMAGNETICANOMALYIMEANSIOOnT(gommos)CONTOURINTERVAL:100 nTINACTIVETRARSFOIIM FAULTBASKOFCONTINEtlTAL SLOPE.UNCONTOURED tlAGNKTIC HIGHMAJORFAULTSg,g~ODCCA3t)036'.Cg~+5ANFRANCISCO 0.5AN)ACRV?01MCNTCRCT~~ATNONTCIICT /I0IIIICo0+000N)LOMCTCN5 37036'5'C3/Q/CVCNON)(.)0J~T,5ACI350I'.ANCVCLL34'2500.I1240-.Yn1230J-,48 FREE-AIRGRAYITY0-04Q~m~mgal-IOO-CALC.SantaLuciaBank0KMIO2.85I.032.250I02.652.2I0203.273.03.23 500)0006VertjoaiExaggeration: XIO ,~~~~~IE0s~W6~SW0sgf,~l.secWBCger.'~eA022.~-'.J.<'nl00~*';~OJj~ .V/11s~JJJJrKnl00~==;.-0Km00rr/g~r.r+Zi"CJ'secW160sW180secW19.J).jo22Km20SodegeOoselForooonJVF.ecsxsecW23 4X0+3ArV.'5uovo5101510ivOtvOH~,01OC~5uo41o!555tuivut'10l5 I4e01OCor7rCOr~OF~rjv'9M~s55vov>ooo5101vutAlp,!,-:.~j~"=..':-~. ~51>)l1<c01OCOCOF0005OrO5v001O;075lO'IvotuCHF'SC,rIJ0000d~r'.rKr5tv~ukDQo5opoQ>ryr$rOrSPrrv01OZCC~Or000001CO05 e80=4020Km0.0PioneerSeamount4+4fe~~4OutcrSontaCruz~~~~~/rForollonRidge20Km0~fMY;0Sec5$Sec$QGuideSeamountl20Km00SantaCruzHigh,ir'0'Km~~d~\~PlrPe.'~r--.-~AV.Ep6X IO80706050KILOMETERS 4020IO020003003CL-OO1JJ40 ~0Stability Considerations ofaFFTTripleJunction0)StableFFT8}Unst'able FFTGordaPacificAmericaPllGWPGVelocityTriangleGordaPacific,America)GAIGlIAlIC)NewStability Condition after(D)RRRAmericaPGPD}Mendocino FFTTripleJunctionGordaAmericayl'PacificPAAPacificPAmeansPacific-AntericaPlateBoundaryplottedonvelocity'riangle J-55 N ~~~'~I~~~~~~4~~~~~~Appchica'".ion ofItnears'Latts'Ltcal mocielsofear&quake magnitucxe versusfault.Iengt>ttnesct!TlaLtng rnaxImu~~ e;,pec'cable earthquaI:es 0~ir~~rr~Nrr'\r~~~r~,'lC~~;1rRobert>xMarl'.S.Geological SurveMenl,Park,California 940"';ABSTRACTCorrelation orlinearrcgrcssion estimates ofearthquai;c magnitude fromdataonliistorical magnitude andlengthofsur-'aceruptureshouldbcbaseduponthecorrectregression. I'orexample,thcregression ofmagnitude onthclogarithm ofthclengthofsurfacenipturcLcanbeusedtoestimatemagnitude, butthcrecession oflogLonmagnitude cannot.Rc~ccssiott cstimatcs arcmostproliable values,andestimates oftnaximumvaluesrequireconsideration ofonewidedconfidence limits.lOOOC'OD~~~~~rr~'INTRODUCHIONInestimating maximumexpectable carthquakcs, itiscommonpracticetoassumeapaximumlengthofsurfacerupture(typically onc-halfthefaultlength)anduse"linesofbestfit"tocstimatcmaximuinmagnitude frontgraphscomparing historical carth-quakcmagnitudes andlcrgtlisofassociated surfaceruptiircs. Thisnotediscusses thcintcrprctatinn anduseoflinearregression orcorrelation modelsforniakingstatistical inferences fromdataon'istorical events.Fnrcxamplc,DnniDaandDuchanan(1970)re-portedlengthofsurfaceruptureLandRichtermagnitude hfforthoseearthquakes forsvhiehthesedatav:ercavailable andprc-scntcd"bestfit"equations ofthcformlngLa+bhf,thatis,thclinearregressinns oflogLnnmagnitude (Fig.1.lincAA').Otheiauthors(fnrexanipie,Tocher,195S;lido,1965)liavccalcu-latedrcgrcssinns ofma<!iiiludc nnlogL(Fig.1,linesDD'ndCC').Iwillarguethatalltheserel!ressinn lineshavebccnusedilt-corrcctly tocstiinate niaxinium earthquake magnitudes frommaximumruplurclenglhs a.'nngfoul!s.Thatis,th"v:rorgregres-sionlinc(lngLoninagnitudc) hasbeenusedtocstimatcniagnitudc fromniaximumrupture)englli,orregression estimates havebeeninterpretetl asmaximuinralherthenninctlikelymal!niluilcs (fnrcxaniplc, Greeneanilnlhers,1973;5'entwnrth andnlhers,1973;KYessonandnthers,1974.1975).ceCJC'>Ir.io>JiOe8e>pctaAs~Ds0ecr4t:ARTHQV/AE use>r'>TUBE 1'igurcl.I.engihnfnt>se>ved sn>beeinpiuieinictstiin> Inesiih.quaken>a::nilude. l.ine*Aissiegiession linenflngl.on>n.>dniin>.c. Linestill,CC',andtill'ic>cpassi>>ntinesuriuagniiude unt>>grJ..l.inAA'ndI)t)'icbasedunihes>>ncdata.K-1GCOLOGY,v.6,p.dG4-4GG,AUGUST,t'ai .rItWACORRELATION MODELManymodelscanbeusedtodrawstatistical inferences fromthcdataonmagnitude andlcng(hofrupture.Atransformation tologI.isusedbccauscittendstonornulizc thcdataandtocn-hanccthclinearrelationship. Forthcpurposeofthisdiscussion, acorrchtion modelispostulated inwhichitisassumedthatnmagnitude versuslogLdatapointsarcranclocnly drawnfromthepopulation ofcarthquakcs 1vithassociated surfaceruptureandthatsuchapopulation hasabivariatc norcnaldistribution (Fig.2).Asindicated blow.theseassumptions arcmorcrcstrictivc thannecessary. AsshowninFigurc2,thcrcgrcssion lincol'onX,orY~a+1}X,passesthroughthcmostprobablevalueofYforeachXandisthcappropriate linctocstimatcYgivenX.Theotherregression linc,thcrcgrcssion ofXonY,passesthroughthcmostprobablevalueofXforeachYandwillnotprovideanunbiasedestimateofYgivenX.Thus.thclineofBonillaandBuchanan(1970}inFigurc1isnotthecorrectregression lineforestimating earthquake magnitude fromfaultlength.Itather,thcappropriate regression ofmagnitude onlogL,calculated usingtheirstrike-slip faultdata,isliucDD'Fig.1).Itissimilartothcequivalent regression linesofthcotherauthors.ESTIV)ATION OFMAXIMUMEARTHQUAYM MAGNITUDES Thcregression linesofrnagnitudc onlogLcanbcusedtoestimatethcmostlikelyrnagnitudc foragivenmaximumrupture.Itmustbcstressedthatsuchanestimateisriotamaximummag-nitude,butratherthcmagnitude thatcouldbcexpectedtobeexceededin50%ofthcearthquakes associated withthatrupturelength.x=ccrcgg0PxItispossibletousethcstatistical modeltoestimatethcmag-nitude,asafunctionoflength,thatcouldbccxpcctedtobecx-cccdcdinagivenproportion (1-cc}ofsurface-rupture occurrences. usingaonc-sided confidence limit(IVonnacott andIVonnacott, 1972,p.280):fcfrr,(L) =ilf(L)+ltcx,s(logL-la~7.)'I-+ I+5(logLl-logZ)~l~twhereM(L}isthercgrcssion value,r,.o,isthccriticalvalueofthcldistribution cvith(n-2}degreesoffrccdom,sisthcstandarderrorofthcrcgrcssion, LlisthcruptureIcnl<hofthcithcarth-quakcoccurrence inthesampleofnearthquakes, andlogListhcmeanoflogL.Thatis,thccurvei'Vx(L)isthclocusofpointssuchthatforaparticular L.I-ccisthcprobability thatthemagni-tudewillcxccedhQ.Notethattheregression lincM(L)isequiva-lenttoM,.,(L}.Asancxamplc,BonnillaandBuchanan(1970)reporteddataonstrike.slip faults(n~20)andcalculated thercgrcssioa linc(Linmctrcs}'ogL~1.915+0.389M,r~0.70,s~Q.S2.Theregression ofMonlogL}acidsM~1.235+1.213logL.r~0.70,s~0.93.TheselinesarcplottedinFigurc3,alongwiththodatapoints.Alsoplottedarcthecurveshf>.>>andM,>>lorthcregression ofMonlogL..Amagnitude valuefromthercgrcssion linc'f(L)canbcrcfcrredtoasthemostlikelym..gnitude foragivenrupturelength,andavaluefromhfJL)asamaximumcxpcctablc carth-quakcmagnitude atcxcccd*nce probability' -cc.ThclineEE'nFigurc3cocmectsthepointsthatformtheright.side cnvelopcofthedata.ThisfieldliescntirclytotheleftofMo>>,andonthcbasisofthcmodel.therearepotential cvcntslargerthanEE'hathaveprobabilities inexcessof5%.Thcprcccding numerical resultsaresomewhatmodeldcpcnd-cnt,inthattheydcpcndonthepopulation distribution andsscnpleselection, butthcgenera)hnplications havewideapplication. Estimates ofmostlikelyearthquake magnitudes foragivenvalueofan"indcpcndent variable" (suchasrupturelengthorfaultdisplacement) mustbebasedonthccorrectrcgrcssion, andesti-matesof"maximummagnitude" rcquircconsideration ofthedistribution aboutthcregression lincandthcapplication ofonc-sidcdconfidence limits.Theseresultscanalsobcderivedfromalessrestrictive lineartcgrcssion modelinwhichlogListreatedasanindependent vari-ableandMisassumedtobcnormallydistributed aboutthcrcgrcssion li>>e(AfonlogL)withvarianceindcpcndcnt ofL(Hays,1973,chap.IS).ll'hedatawarrant,thcscmodelscouldbeex-pandedtoincludeadditional "independent variables" suchastectonicsettinganclhypoc.cntral depth.Astatistical approachisalsonccdcdtocsticnatc thcmaximuntsurlaccrupture(atsomecxcccdance probability) foragiventotalfaultlength.Flcclcc2,'Yhctcvoccyccs)loll thwsic)0t)lvaliatc llocmatpop))tattoo, ccontoc)czindicatectealpc))tat)ilitydensity,~t)))tificd frocu4'vc)c)acutt and4ocmacoct tt97)).xcecdance pcobability istheprobability thatsomcthi))t., inthiscasemat.nitudc, vcttt)ccxcccdcd. GP.OLOGYK-2 QI)30h~hsRrgolsv4~4Don)()a,hl.G.,andBuchanan, J.I'l.,1970.Interimrcportontvorldsvidchistoricsurfacefaulting: U.S.Geol.SurveyOpenFilel(ep(.,32p.Grccnc,SV.H.,I.ec,W.l).IL,hlcColloclh ILS.,andBrabb,)LI1973.I'aultsandearthquakes inthchtontcrey Dayregion,California: U.S.Geol.Surveytexttnaccompany mapMF518,14p.)lays,W.L.,)973,Statis(ics forthcsocialscicncesr NcsvYork,)lolt.

Rinehart, andWinctnn,954p.lida,Numizi,196S,I'.arthquakc magni(ude, earthquake faultandsourcedirncnsions:

NagnyaUniv.Jour.ForthSci.,v.)3,p.II5~)32.Tochcr,Don,1958,Lsar(l>qua),"e energyandgroundbreakage( Seismol.Soc.AmericaBull.,v.48.p.147-)53.Wcsson,R.L.,I'agc,R.A.,Boore,D.hl.,andYerkcs,R.I'.,1974,Isx.pcctablecarthquakcs inthcVanNo(roanReservoirs area:U.S.Geol.SurveyCirc.69)-B,9p.Wcsson,R.L.,)le)Icy,E.J.,Lajoie,K.R.,andWcnttvorth, C.M.,1975,Faultsandfutureearthquakes, fnIrorcherdt. R.D.,cd.,StudiesforseismiczonationofthcSanFrancisco flayregion:U.S.Geol.SurveyProf.Paper9CI-A,p.AS-A30.Wenhvorth, C.h'l.,Beni))a,M.G.,andBuchnan,J.hl.,1973,Seismicenvironment ofthcBurroFlatssite,VenturaCounty.California( U.SGeol.SurvryOpen.File Rcpt..35p.Wonnacott, Thorn..sH.,andWonnacott, RonaldJ.,19'12,introductory statistics forbusinessandeconomics: NcsvYork,Wiley,622p.J(CIÃQAYLEDGM EHTSRcvicwcdbyD.R.Dasvdy,D.G.Ilcrd,R.A.Page.andD.hl.Perl:ins. hlANUSCRIPT RECEIVEDAPRIL27,1977MANUSCRIPT ACCEPTEDMAY3,1977IA3q85C66078KARTHQVAN\ s(AH(TVDE Figurc3.Lengthofobscrvcdsurfacerupturcvcrsus earthquake magnitude forthcstrikeslipfaultda(aofllunithandLtuchanan (1970).LincAA'sthcregression lincol'ng1.onmacnitude amlcouldbeusedloestimatethcntostlikelytuplurclengthassociated svithagivenmagni.tudcearthquake. I.incIIps'stherctuessiunlineofmagnitude onlogIandc'ouidbcusedtocstunatethcmustlikelyearthquake tnagnitude associated witharivenlrngthofsurface(upture.Onthcbasisoi'hccorrelation rnnAI,halfthccarthqua'kcs associated withagivenlengthufsur(accrup(urerouhlbceapcctcii (ulsclargerthanIIIJ.Themarnitudcs 'givenbylincDl)'ou)Jbceapec(cdtnexceed95%,ofthea(agni(udes furearthquakes assucia(ed withagivenI;ngthofsurface(up(urc.ThclincEE'stheri).ht.sh(c envelopeofobserveddata.K-3~WHlleINvsaAUGUSi

ATTACHMENT LUNITEDSTATESDEPARTMENT OFTHEINTERIORGEOLOGICAL SURVEYREGRESSION ANALYSISOFEARTHQUAKE MAGNITUDE ANDSURFACEFAULTLENGTHUSINGTHE1970DATAOFBONILLAANDBUCHANANByR.K.MarkandM.G.BonillaPreparedincooperation withU,S.NuclearRegulatory Commission. OPENFILEREPORT77-614Thisreportispreliminary andhasnotbeeneditedorreviewedforconformity withGeological Surveystandards andnomenclature. MenloPark,Ca1ifornia1977 REGRESSIOH ANALYSISOFEARTH(UAKE MAGNITUDE AHDSURFACEFAULTLENGTH,USINGTHE1970DATAOFBONILLAANDBUCHANANByR.K.Harkandt1.G.BonillaIntroduction. ThereportofBonillaandBuchanan(1970)includesre-gressions offaultlengthonearthquake magnitude thatcanbeusedtoestimatemostprobablelengthofsurfacerupturegivenearthquake magni-tude.Thoseregressions, however,havesometimes beenincorrectly usedtoestimatemagnitude fromfaultlength,aspointedoutbyHark(1977).UsingthedataofBonillaand'Buchanan, thisreportgivesregressions ofearthquake magnitude onlengthofsurfacerupturethatcanbecorrectly usedtoestimatemostprobablemagnitude ifthelengthofsurfaceruptureisgiven.Italsogivestheregressions oflengthofruptureonmagnitude thatcanbeusedtoestimatemostprobablelengthofrupturegivenearth-quakemagnitude. Intable1andfigures1-5thenumbering andlettering systemusedtodesignate faultgeography andfaulttypesisthesameasinBonillaandBuchanan(1970).Numbers1-49includesurfacerupturesthatoccurredinNorthAmericaandnumbers50-140includerupturesoutsideofNorthAmerica.Thefaulttypesareindicated bylettersasfollows:A,normal-slipfaults;8,reverse-slip faults;C,normaloblique-slip faults;0,reverseoblique-slip faults;andE,strike-slip faults.Useofthereressionlines.Theregression ofloglengthonmagnitude L-2 ~~(LogL=a+bM)canbeus<<dtoestimatethemostprobablerupturelengthgivenmagnitude, andtheregression ofmagnitude onloglength(M=a+bLogL)canbeusedtoestimatethemostprobablemagnitude givenrupturelength.Theestimation of'maximummagnitudes'or agivenrupturelengthrequirestheuseofone-sided confidence limits(Hark,1977).References citedBonilla,H.G.,andBuchanan, J.M.,1970,Interimreportonworldwidehistoricsurfacefaulting: U.S.Geol.Surveyopen-file rept.,32p~Mark,R.K.,1977,Application oflinearstatistical modelsofearthquake magnitude versusfaultlengthinestimating maximumexpectable Y.Sqp+~++6b~AUQ0sl.earthquakes: Geology,+a-p~.'AL-3 Table1Regression analysisofmagnitude -surfac'erupturelengthdatafromBonillaandBuchanan(1970).fset1-49nr~200.3?21-140530.257140.17570.00370.45950.00650-140330.21710.64.8.57.Log(L)=a+b~Hab-0.910.35-1.490.402.550.014.240.02-0.690.28notsignificant -2.810.61notsignificant 17.62-0.960.34N=a+b*Log(L) b1.080.540.760.630.900.640.800.680.386.080.750.42sa0.51'.230.556.560.536.030.456.19-EA+C210.2797.37-1.460.40200.484.16.87-1.080.390.524.960.456.131.240.930.700.59B+DC+D+E120.0330.34320.36717.42-1.240.40notsignificant 0.555.620.93084120.'2302.99-2.790.590.576.620.390.47B+E270.29910.65-0.710.320.565.710.940.97A+C+E410.38023.94-1.200.390.495.560.990:79B~D+E320.25110.07-0.810.320.605.980.780.93Notes"n"isthenumberofcases."t"isthefractionofthevarianceexplained bytheregression. Itrangesfrom0(nolinearrelationship) to1(perfectlinearrelationship). "f"isameasureofstatistical significance oftheregression andisequaltor~/.((1-8)(n-2))."L"isinkilometers. "s"isthestandarderroroftheestimate. s~isequaltotheresidualsumofsquareerrorsabouttheregression linedividedbythedegreesoffreedom(i.e.,n-.2).L-4 SICKO,800'0060050Q40050020Q0KELJIOO090hC8070I-6oDu.5040soDI-20SORLDV/!DE DATA0Ob.IO0987Rld65O0X0/tp0hO+OEOI/O05tEARTH'QUAKF MAGNITUOE L-59Fip.l IOOO800eOO700600500400300200MLIJI-IOO09080hC706050NORTHAMERICANDATA40<<KQJ30ILI-LL.20KLalOIoLL.9O8I-7Z6LLJV~o~OaOO4Q6EARTKQUAKE MAGNITUDE L-67'9Fig.2 9oo~'(~800700600500400500200V)CLLalleloo0908070I-Go50NORMAL-SLli~ FAULTDATA40ZsoKI-tL20u-,lo0987R650'0XCnO0+Cb56EARTHQUAKE MAGNITUDE L-7/) IOOOeno800700600500400500200VlfLldI-ion0908070I~60U50R40lLsoDI-020ORBALOBLIQUE-SLtPFAULTDATAOKDlo09I-8LU50OhO+DCOII56EARTHQUAKE MAGNITUDE L-8 .aoo000700600500400300200COLLII-ObCLL.IOO9080706050STPiIViE-SLIPFAULTDATAcfLLJI-tLDLLjCDtOLLOxI-E9zLLJ403020lo87650o'./jChO0)56EARTHQUAK EMAGNITUDE I~ ~g'~INAMEJamesN.BruneATTACHMENT MBIRTHDATE (MO.,DAY,YR.)November23,1934BIOGRAPHICAL SKETCH(PROVIDEFOLLOWING INFORh)ATION FORALLPROFESSION~RSONNEL ENGAG~TIIEPROJECT,BEGINNING WITHTHEPRINCIPAL ~TIGATOR.) PLACEOFB(RTH(CITY,STATE,COUNTRY)Modesto,California U.S.A.PRESENTNATIONALITY (ALIENSINDICATEKINOOFVISAANDEXPIRATION DATE)U.S.CitizenEDUCATION (BEGINWITHBACCALAUREATE TRAININGANDINCLUDEPOSTDOCTORAL) DEGREEB.Sc.Ph.D.YEARCONFERRED 19561961INSTITUTION ANDLOCATIONUniversity ofNevada,Reno,NevadaColumbiaUniversity, NewYorkCityHONORSANDAWARDSSeeAttachedMAJORRESEARCHINTERESTEarthquake SourceMechanism Tectonics EarthStructure RESEARCHAND/ORPROFESSIONAL EXPERIENCE (STARTING WITHPRESENTPOSITION, LISTPROFESSIONAL BACKGROUND ANDEh'IPLOYMENT) Professor oIGeophysics-University ofCalifornia, San'Diego, 1969-Associate

Director, Institute ofGeophysics andPlanetary Physics,University ofCalifornia, SanDiego,1973-1976..Chairman, Geological ResearchDivision, ScrippsInstitution ofOceanography, University ofCalifornia, SanDiego,1974-1976.Associate Professor ofGeophysics-California Institute ofTechnology, 1965-1969.AdjunctAssociate Professor ofGeology-Columbia University, 1964.Geophysicist, U.S.CoastandGeodeticSurvey,1964.ResearchScientist, ColumbiaUniversity, 1958-1963.'xploration

Research, ChevronOilCompany,1957.Exploration Geophysics, ChevronOilCompany,1956.

UCSD-0071 JamesN.Brune.HONORSHigginsFellowship, ColumbiaUniversity, 1956University Fellowship inGeophysics, ColumbiaUniversity, 1957-58i)axFleischr~~an Scholarship, University ofNevada,1954-55Jones-Hoover Scholarship, University ofNevada,oneyearJ.B.HacIlwane AwardofAmericanGeophysical Union,1962FellowoftheAmericanGeophysical Union,1967GroveKarlGilbertAwardinSeismicGeology,1967Seismol'ogical SocietyofAmerica:BoardofDirectors, 1967-present, Yice-President, 1969,President, 1971Meri>berofNewYorkAcaderi>y ofSciences, 1970ArthurL.DayAward,1972G..K.GilbertAward,CarnegieInstitution ofWashington, 1967Llstlngsinvhosvhointhevest,kne2icanZenofscienceM-2 BIBLIOGRAPHY JamesN.Brunel.2~(WithJ.Oliver)TheSeismicNoiseoftheEarth'sSurface,Bull.Seism.Soc.Amez.,49:4,349-353(1959).(WithJ.E.NafeandJ.E.Oliver)ASimplified MethodfortheAnalysisandSynthesis ofDispersed HaveTrains,Jour.Geophys.Res.,65:1,287-304(1960).3~(WithJ.E.Nafe)Observations 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ofJuly6,1962,Bull.Seism.Soc.Amer.,55:5,805-819(1965).(WithL.E.Alsop)Observations ofFreeOscillations ExcitedbyaDeepEarthquake, Jour.Geophys.Res.,70:24,6165-6174 (1965).TheSaPhasefromtheHinduKushEarthquake ofJuly6,1962,PureandAppliedPhysics,62:3,81-95(1965).PandSWaveTravelTimesandSpheroidal NormalModesofaHomogeneous Sphere,Jour.Geophys.Res.,71:12,2959-2965 (1966).(WithJ.Oliver,A.RyallandD.Slemmons) Micro-earthquake ActivityRecordedbyPortableSeismographs ofHighSensitivity, Bull.Geol.Soc.ofAmer.,56:4,899-924(1966).(WithR.C.Liebermann, C.Y.KingandP.W.Pomeroy)Excitation ofSurfaceWavesby'theUnderground NuclearExplosion LongShot,Jour.Geophys.Res.,71:18,4333-4339 (1966).F(WithC.R.Allen)AMicro-earthquake SurveyoftheSanAndreasFaultSysteminSouthernCalifornia., Bull,.Seism.Soc.Amer.,57:2,277-296(1967).(WithC.R.Allen)ALow-stress-drop, Low-magnitude Earthquake withSurfaceFaulting: TheImperial, California, Earthquake ofMarch4,1966,Bull.Seism.Soc.Amer.,57:3,501-514(1967).(WithM.Wyss)TheAlaskaEarthquake 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congress, FirstSessiononExtentofPresentCapabilities forDetecting andDetermining NatureofUnderground Events,133-142(October27-28,1971).~~r~(withW.Prothero)

"ASuitcaseSeismicRecording System",BulZ.Seism.Scc.Amez'.,6Z,6,1849-1852 (December, 1971).4~(withD.McKenzie) "MeltingonFaultPlanesDuringLargeEarthquakes", Gecpnus.J.B.as'.Soc,29:1"(.1972). (withD.Oldenburg) "RidgeTransform FaultSpreading PatterninFreezingWax,Science,Vol.178(1972)301.M-6 52.C.R.Allen,M.Myss,J.N.Brune,A.GrantzandR.E.Wallace."Displaccments ontheImperial, Superstition Hills,andSanAndreasFaultsTriggered bytheBorregoMountainEartnquake". InU.S.G.S., Prof.Paper8787,pp.87-104(L972),53.t54.B.E.TuckerandJ.N.Brune.."Seismograms, S-WaveSpectraandSourceParameters forAftershocks oftheSanFernandoEarthquake ofFebruary9,1971."I/OAASpecialReport,1973,I.Reid,M.Reichle,J.BruneandH.Bradner."Microearthquake StudiesusingSonobuoys: Preliminary ResultsfromtheGulfofCalifornia." Geophys.J'.B.astr.Soc.,34,365-379(1973).55,J.N.Brune,S.delaCruz,H.Bradner,C.Villegas, I.Reid,M.Reichle,'A.Nava,M.LozadaandP.Silva."Earthquakes intheGulfofCalifornia RecordedusingLand-Based Recordings ofMooredHyd.ophone Arrays."Geofisica Zrit.,12(3),201-212(L972).56.J.N.BruneandC.Lomnitz."RecentSeismological Developments RelatingtoEarthquake Hazard."Geofisica Znt.,14:pp.49-63(1974),"57.P.Molnar,B.E.TuckerandJ.N.Brune."CornerFrequencies of'andSHaves8Models'oEEarthqu'ake Sources,"'ull. Seismo.Soc.i'.,63,2091-2105 (1973).58.59.F.Gilbert,A.Dziewonski andJ.Brune."AnInformative SolutiontoaSeismological Inverse.roblem". Proc.Efat'l.Acad.Sci.,70,5,pp.1410(1973.).W.ThatcherandJ.N.Brune."Surfacewavesandcrustalstructure 'ntheGulfofCaliforn'ia region."Bull.Seism.Soc.Am,63,5,1689-3.698 (1973).60.Brune,J.N."Earthquake modelling bystick-slip alongpre-cutsurfacesinstressedfoamrubber".Bull.Seism.Soc.Am.,63,.~.6.,2105-2119. (197,3).61.62.63.64.65.Brune,J.N.andF.Gilbert,"Torsional OvertoneDispersion fromCorrela-tionsofSWavestoSSWaves",Bull.Seiam.Soc.Am.,64(2),313-320-(1974).H.BradnerandJ.Brune,"TheUseofSonobuoys inDetermining Hypocenters ofAftershocks oftheFebruary21,.1973Pt.MuguEarthquake," ~l.l,.Am.,64,No..l,99-101,1974.J.N.Brune,"CurrentStatusof.Understanding Quasi-Permanent FieldsAssociated withEarthquakes",'EOS, 55,No.9,1974.tD.M.Oldenburg andJ.N.Brune,"AnExplanation fortheOrthogonality ofOceanRidge"and.Transform Faults",J.Geophys.Res.,80,no.17,.p.2575,1975.AlfonsoReyes,J.Brune,L.Canalcs,J,Madrid,J,Rebollar, L.Munguia,T.Barker,"AMicroearthquake SurveyoftheSanMiguelFault,BajaCalifornia, Mexico",Geophys, Res.Lttrsp2)56593975.M-7 JamesN.Bruno-B'ography Page1~a66,JamesBrune,CinnaLomnitz,ClarenceAllen,Fredorico Hooser,FrancisIohnor,~andAlfonsoReyes,"APermanent Seismograph ArrayAroundtheGulfofCalifornia," Z~li'.Soi.one.8o'~.Am.,66,969-978,1976.67.RalphArchuleta andJamesN.Brune,"SurfaceStrongMotionAssoc-ated withaStick-Slip EventinaFoamRubberModelofEarthquakes "Bull,Soismo.Soc.Am.,65,1459-1071, 1975.68.69.70.BrianE;TuckerandJ.N..Brune, "SourceHechanism andSurface-wave-Excitation forAftershocks oftheSan,FernandoEarthquake", Geophys.J.R,astr,Soc,,4937>~426)>977r.HichaolReichle,GeorgeSharman,andJamesBrune,"Sonobuoy andTeleseismic StudyofTwoGulfofCalifornia Transform FaultEarthquake Sequences", Bull.Seisrrio. Soc.Amer.,66,1623-1642, 1976.'illiamA'.Prothero., IanReid,MichaelReichle,JamesBrune,'Ocean-BottomSeismicMeasurements ontheEastPacificRiseandRiveraFractureZone",Nature,262,121-124,1976.71.GeorgeF.SharmanrMichaelSrReichle>James.N,Brune,"ADetailedStudyofRelativePlateHotionintheGulfofCalifornia," Geology,April;pp.206-210$1976.II72.StephenH.HartzellandJamesN.Brune,"SourceParameters fortheJanuary>1975Brawley-ImperialValleyEarthquake Swarm"PAGEOPH,1151977.73.JamesN.Brune,AlfonsoReyes,MichaelS.Reichle,"RecentSeismicand'Tectonic StudiesoftheGulfofCalifornia", CIBCASIOAnnualReport,1976.74.75..76.JamesN.Brune,R.Archuleta, J.Frazier,G.Hegemier, "Physical andNumerical ModelingofSpontaneous Slip",sugaryoftalkgivenatNorthwestern University atNSFWorkshopon"Application ofElasticWavesinElectrical Devices,Non-Destructive TestingandSeismology" Hay24-26,1976.1JamesN.Brune,"QofShearWavesEstimated fromS-SSSpectralRatios,"Geophys.Res.Lttrs.,4,No.5,1977.Stephen.H.

Hartzell, GeraldA.FrazierandJamesN.Brune,Earthquake modelinginahomogeneous half=space,r'ull.

Seism.Soc.A'm.,68,301-316,'978.77.KeithPriestley andJamesN.Brune,"SurfaceWavesandtheStructure oftheGreatBasinofNevadaandWesternUtah",acceptedforpubli-cation,1977.78.LuisMunguia,M,Reichle,A.Reyes,R.Simons,J.N.Brune,"Aftershocks ofthe8July1975CanalDeLasBallenas, GulfofCalifornia, Earthquake", Geaphysical'es. Lttr.',4,No.11,1977.M-8: 79,J.N.Brune,"implications ofEarthquake Triggering andRupturePropa-gationforearthquake Prediction BasedonPremonitory Phenomena", presented atUSGSConference onFaultMechanics anditsRelationtoEarthquake Prediction, December1-3,1977.80.J.N.Brune,R.J.Archuleta andS.H.Hartzell, "Far-Field S-WaveSpectra,CornerE'requencies andPulseShapes",presented atUSGS'onference onFaultMechanics anditsRelationtoEarthquake Prediction December1-3,1977..81.StephenHartzell, JamesN.BruneandJorgePrince,"TheOctober6,1974AcapulcoE'arthquake andtheimportance ofShortPeriodSurfaceWavesinStrongGroundi~fotion, inpreparation, 1978.82.JamesN.Brune,"Statement totheACRS"meetfhSbmeetingoteSubcommittee oftheAdvisoryCommittee onReactorSafeguards, LosAngelesCalifos,aornia,83.StephenHartzellandJamesN.Brune,"Analysis oftheBucharest StrongGroundMotionRecordfortheMarch4,1977RomanianEarthquake", inpreparation, 1978.84.A.Reyes,J.N.BruneandC.Lomnitz,"SourceMechanism andAftershock StudyoftheColima,MexicoEarthquake ofJanuary10,1973",inpre-paration, 1978.85.StephenHartzellandJamesN.Brune;"TheHorseCanyonEarthcuake ofAugust2,1975-TwoStageStressReleaseProcessinaStrike-Slip Earthquake", inpreparation, 1978.M-9 ~k~ ~~ATTAIEI<TNCurxiculum VitaeforJ.EnriqueLucoBirthDate:May18,1943-VinadelMar,ChileEducation: WScientific Research: Ph.D.University ofCalifornia, LosAngeles-1969.CivilEngineer, University ofChile,Santiago-1967.Includesstudiesontheeffectsofgeologyandlocalsiteconditions onearthquake groundmotion;dynamxcresponseo~zoundaticns; "oil-str"ct ~rcinteraction duringearthquakes; wavepropagation onasimplified modeloftheEarth;evaluation ofearthquake damage;earthquake responseofnuclearpowerplants;forcedvibxations ofstructures. Employment; Associate Professor ofAppliedMechanics, University ofCalifornia, SanDiego,1977<<present. Assistant Professor ofAppliedMechanics, University ofCalifornia, SanDiego,1974-1977. SeniorResearchFellowinAppliedScience,California Institute ofTechnology,'973-1974. Researcher, Department ofGeophysics, University ofChile,1970-1973. Professor intheDepartments ofMathematics andPhysics,University ofChile,1971-1972. ResearchFellowinAppliedSciences, California Institute ofTechnology, 1970.ResearchAssistant, Department ofGeophysics, UniversityofChile,1965-1967.Professional Societies Membership: AmericanSocietyofCivilEngineers. Seismo)ogical SocietyofAmerica.Am'erican AcademyofMechanics.

SigmaXl, Publications ofJ.E.'Lucol.1967.ProaationofHih-FreuencComressional PulsesinaLaeredSphere,CivilL'ngincer Thesis,FacetteddeCienciasFisicasyMatematicas, Universidad deChile,Santiago, Chile(Publication No.45,Department ofGeophysics, University ofChile,Santiago).

2.1969."DynamicInteraction ofaShearWallwiththeSoil,"J.Engineering Mechs.Div.,ASCE,Vol.95,No.EM2,April,pp.333-346.. 3.1969.AlicationofSingularInteralEuationstotheProblemofForcedVibrations ofaRiidFoundation, Ph.D.Dissertation, SchoolofEngineering andAppliedScience,University ofCalifornia, LosAngeles.(December). ~4.1970."DynamicSoil-Structure Interaction," withHradilek, P.J.,InformeTecnicoNo.14Instituto deInvestigaciones EnsaesdeMateriales (IDIEM),Universidad deChile,Santiago, Chile.5.1970."StrongEarthquake MotionandSiteConditions: Hollywood, "withDuke,C.M.,Carriveau, A.R.,Hradilek, P.J.,Lastrico, R.,andPstrom,D.,Bull.SeismeSoc.Amer.,Vol.60,No.4,August,pp'.1271-1289. 6.1971."DynamicResponseofCircularFootings," withWestmann, R.A.,Engineering ReportNo.7113,SchoolofEngineering andAppliedScience,University ofCalifornia, LosAngeles(April).7.'971."DynamicResponseofCircularFootings," withWestmann, R.A.,J.EnineerinMechs.Div.,ASCE,Vol.97,No.EM5,October,pp.1381-1395. 8.1971."InformePreliminar, sobreIntensidades yDanoscausadosporelSismode8deJuliode1971:ZonaCalera-Illapel," withLastrico, R.,andMedone,C.A.,RevistaGeografica, deChile,No.21,pp.14-19,Santiago, Chile.9.1972."APreliminary Report,TheJuly8,1971ChileanEarthquake, "withEisenberg, A.,andHusid,R.,Bull.SeismeSoc.Amer.,Vol.62,No.1,February, pp.423-430.10,1972.DynamicResponseofaRigidFootingBondedtoanElasticHalf-Space,"withWestmann, R.A.,J.Al.Mech.,ASME,Vol.39,SeriesE,No.2,June,pp.527-534.N-2 ~~a~ll,.1972."ElTerremoto deSanFernandoenCalifornia," withLastrico, R.,RevistadelaConstruccion, AnoXI,No.117,Junio-Julio,

Santiago, Chile.12.1972.rr~~rr"Ingenieria SismicaenChile:unaBibliografia, "InformeTecnicoNo.15,Instituto deInvestigaciones EnsaesdeMateriales (IDIEM),Universidad deChile,Santiago, Chile.13.1973."DynamicStructure-Soil-Structure Interaction,"

withContesse, L.,Bull.Seism.Soc.Amer.,Vol.63,No.4,August,pp.1289-1303. 14.1973."Vibraciones Horizontales deunDiscoRigidosobreunSemiespacio Elastico," RevistadelInstituto deInvestizaciones EnsavesdeMateriales (IDIEM),Vol.12,No.1,pp.1-13,Universidad deChile,Santiago, Chile.15.1974."Soil-Structure Interaction -Continuum orFiniteElement", "withTsai,N.C.andHadjian,A.H.,NuclearEn~ineerin andDesign,Vol.31,No.2,pp.151-167.16,1974."TheDynamicModelingoftheHalfPlanebyFiniteElements," withBos,H.,andHadjian,A.H.,NuclearEnineeringandDesign,Vol.31,No.2,pp.184-194.17.1974."Two-Dimensional Approximations totheThree-Dimensional Soil-Structure Interaction Problem," withHadjian,A.H.,NuclearEnineerinandDesi,Vol.31,No.2,pp.195-203,18.1974."Impedance Functions foraRigidFoundation onaLayeredMedium,"NuclearEnineerineandDesign,Vol.31,No.2,pp.204-217,19.1975."FullScale,ThreeDiiYlensio.al TesoStrctr1Deormations DuringForcedExcitation ofaNine-Story Reinforced ConcreteBuilding," withFoutch,D.A.,Tzifunac, M.D.,andUdwadia,F.E.,Procecdin sU.S.Nation"1Conference onEarthquake 920.1975."AnExperimental StudyofGroundDeformations CausedbySoilStructure Interaction," withTrifunac, M.D.,andUdwadia,F.E.,Proceedings U.S.NationalConference onEarthuakeEn~ineerin June,1975,AnnArbor.21.1975."ANoteontheDynamicResponseofRigidEmbeddedFoundations," with%'ong,H.L.,andTrifunac, M.D.,Earthquake Engineering andStructural

Dynamics, Vol.4,No.2,pp,119-128.

22.1975."DynamicModelingofaViscoelastic Half-Space byFiniteElements," withHadjian,A.H.andAtalik,S.,Proceedings SecondASCEConference onStructural DesinofNuclearPlantFacilities,

December, 1975,NewOrleans.23.1976."Torsional ResponseofStructures toObliquely IncidentSHWaves,"EarthuakeEnineeringandStructural namics,Vol.4,No.3,January-March, pp.207-219.24.1976."Torsional ResponseofStructures forSH-Waves:

theCaseofHemispherical Foundations," Bull.Seism.Soc.Amer.,Vol.66,No.1,February,,pp. 190-123.25.1976.",Vibrations ofaRigid'Disc onaLayeredViscoelastic Medium,"NuclearEnineeringandDesin,Vol.36,No.3,March,pp.325-340.26.1976."TorsionofaRigidCylinderEmbeddedinanElasticHalf-Space,"JournalofApliedMechanics, Vol.43,SeriesE,No.3,September, pp.419-423.27.1976."DynamicResponseofRigidFoundations ofArbitrary Shape,"withWong,H.L.,EarthIakeEngineering andStructural 6,*-*..9-928,1976."Torsional ResponseofaRigidEmbeddedFoundation," withApsel,R.J.,J.oftheEn@re.Mech.DivesASCE,Vol.102,No.EM6,December, pp.957-970.29.1977."DynamicResponseofRectangular Foundations forRayleighWaveExcitation," withWong,H.L.,Proceedings oftheSixthWorldConference onEarthuakeEngineering, NewDelhi,India.30,1977."OntheImportance ofLayeringontheImpedance Functions," withHadjian,A.'H.,Proceedings oftheSixthWorldConference onEarthuakeEngineerin, NewDelhi,India.31.1977."ContactStressesandGroundMotionGenerated bySoil-Structure Interaction," withWong,H.L.andM.D.Trifunac, Earthqualce EnineerinzandStructural namics,Vol.5,No.1,January-March,pp.67-69.32.1977."TheApplication ofStandardFiniteElementProgramsinthe'Analysis ofSoil-Structure Interaction, 99withWong,H.L.,Proc.oftheSecondSAPUser'sConference, UmversitofSouthernCalifornia, June1977,LosAngeles. ~~l~EI~I33.1977.34.1978."SeismicResponseofaPeriodicArrayofStructures," withMurakami, H.,Z.oftheEngrg,Mechs.Div.,ASCE,Vol.~103No.EM5,Oct.>pp.96~-977.r"DynamicResponseofRectangular Foundations toObliquely "itEnineerinandStructural Damies,Vol.6,Zan.,pp.3-16.N-5 "~hi,P~ ~'~~~ATTNEHT0CURRICULUM. VITAEFORiVIIHAILO D.TRIFUNACBirthDate:ggG]75787November1942K'kinda,Yugoslavia Ed"caon:Pn.D.Califor.iInst'tute ofTe"hnology,CivilEnginee"ingandGeophysics, 1969M.S.Princeton. University, CivilEngineering, 1966B.S.University ofBelgr-de, CivilEngineering, 1965Scientific Research: Includesinvestiga ionofstrongearthquake ground.motionsfollowing Parkfield, California, 1966earthquake (1967+);high-frequency resolution andstrong-motion mechanism studyofImperialValley,California 19-"0earthquake (1968+);siznplemathematical modelsofanalluvialvalleysubjecttostrongearthquake motion(1968+);ambientandforcedvibration studiesofseveralmulti-story structures (1968+);laboratory evaluation 'nd,instrument correction methodsofstrongmotionaccelerogzaphs ()970+);development ofthedataprocessing methodsofstrong-motionaccelerograms (1970+);satisticsandtriggering mech"nismofearthquakes (1968+);studiesofmicrotremor vibrations theImperialValley(1970+);studyofnetmethodsforsynthesizing artificial stronggroundzwotion(1970+);investgationofthesoil-structure interaction (1970+);amplification and.focusingeffectsincomplicated geologicstructures (1971+);stressestimates and.sourcemechanism studiesofearthquakes based,ontherecordedstrong-motionaceelexograms(1971);development ofseismicdesigncriteria. intermsofrespozise spectra(1975+);developr.entofapproximate scalingmethodsfozstrongearthquake groundmotonintermsofpeakaccelerations, velocities anddispla'ements (1975+);studiesondurationofstrongeathquakegroundmot'on(1974+);soil-bridge-soil interaction'roblems (1975+);soil-structure-soil.-structure interaction problezns (1975+).~l~~~pro>c:nOv C~ggg,LgbpillCCIp)Qp$J0p+pgg~Qp(.JJQ)Q ~/Oft(l(I(0ssistantProfessor ofAppliedS'cience, Calif'ornia Institute ofTechnology, 1972-l'l')~ResearchAssociate, Lamo..t-Doherty Geological Observatory andLecturerintheDepartment ofGeologyofColumbiaUniversity, 1971-1972 ResearchScientist, Lamont-Doherty Geological Observatory ofColumbiaUniversity,1970-1971ResearchFel'o.v'..nAppliedlvlechanics, California Institute ofTechnology, July1969-September 19700-1 i~~tM.D.TrifunacCurriculum VitaePageTv'oResearchAssistant, California Institute ofTechnology, 1966-1969 ResearchAssistant, Princeton University, 1965-1966 Consultant toAdvisoryCommittee onReactorSafeguards, 1971-ProfssionalSocieties: AmericanGeophysical UnionAmericanSocietyofCivilEngineers Seismological SocietyofAmericaSigmaXiEarthquake Engineering ResearchInstitute Teaching~ Experience: Caltech:-2.4,ColumbiaUniversity:l..3'Ij6940y'-Strong-Motion Seismology (1971-72) CE180-Experimental MethodsinEarthquake Engineering CE181-Principles ofEarthquake engineering CE1S2-Structura1.DynamicsofEarthquake Engineering OtherSelectedActivities andEwmerience: ServedonthePanelonStrong-Motion Seismology, Committee 'nSeismology,'at. Acad.ofSciences; Participated. inUNESCOSymposium ofExpertsonStrong-MotionSeismology; Participated, inATC-3effortforimprovement ofEarthquake Resistant DesignCode;Presented over50scientific papersduringnationalandinternational conferences. 0-2 ~,g~~~~'~Scientific Publications of.M.D.Txifunac1.1967Z.19693.1969Analysisofaccelerograms -Parkfield earthquake, withG.W.Housner,Bull.Seism.Soc.Amer.,57,1193-1220. 'IAnalysisofstrong-motion accelerograph records,withD.E.HudsonandN.C.iXigazn,FourthWorldConference onEarthquakeEngineering,

Santiago, Chile.Strong-motion earthquake accelerograms, digitized andplotted.data,Vol.I,withD.E.HudsonandA.G.Brady,Earthquake Engineering ResearchLaboratory, EERL70-20,California Institute ofTechnology, Pasadena.

4.1969Investigation ofstxongeaxthquake ground'motion,Earthquake Eng.Res.Lab.,Calif.Inst.ofTech.,Pasadena. 5.1970AnalysisofthestationNo.2seismoscope record-1966,Parkfield, California, earthquake, withD.E.Hudson,Bull.Seism.Soc.Amer.,60,735-794.6.19707.1970Windandmicrotremor inducedvibrations ofa22-storysteelframebuilding, Earthquake Eng.Res.Lab.,EERL70-.01,Calif.Inst.ofTech.,Pasadena. Complexity ofenergyrelease.duringtheImperialValley,California,, earthquake of1940,withZ.N.Brune,Bull.Seism.Soc.Amer.,60,137-160.8.1970Ambientvibration testora39-storysteelframebuilding, Earthquake Eng.Res.Lab.,EERL70-02,Calif.Inst.ofTech.,Pasadena. 9.1970Onthestatistics andpossibletriggering mechanism ofearth-quakesinSouthernCalifornia, Earthquake Eng.Res.Lab.,EERL70-03,Calif.Inst.'fTech.,Pasadena. 10.1970Laboratory evaluation andinstrument coxrections ofstrong-motionaccelerographs, Earthquake Eng.Res.Lab.,EERL70-04,Calif.Inst.ofTech.,Pasadena. 11.1970Responseenvelopespectrumandinterpretation ofstrongearth-quakegroundmotion,Earthquake Eng.Res.Lab.,EERL70-06,Calif.Inst.ofTech.,Pasadena.. 12.1970Lowfrequency digitization errorsandanewmethodforzerobaselinecorrection ofstrong-motion accelerograms, Earthquake Eng.Res.Lab.,EERL70-07,Calif.Inst.ofTech.,Pasadena. 0-3 1971IResponseenvelopespectrumandinterpretation ofstrongearth-quakegroundmotion,Bull.Seism.Soc.Amer.,~61343-356.14.197115.1971Zerobaselinecorrection ofstrong-motion accelerograms, Bull.Seism.Soc.Amer.,61,1201-1211. Amethodforsynthesizing realistic stronggroundmotion,BulL.Seism.Soc.Amer.,~611755-1770. 16.1971Surfacemotionofasemi-cylindrical alluvialvalleyforincidentplaneSHwaves,Bull.Seism.Soc.Amer.,61,1739-1753. 17.1971AnalysisofthePacoimaDamaccelerogram, SmFernando, California, earthquake of1971,withD.E.Hudson,Bull.Seism.Soc.Amer.,~611393-1411. 18.1971191971Highfrequency errorsandinstrument corrections ofstrong-motionaccelerograms, withF.E.UdwadiaandA.G.Brady,Earthquake Zng.Res.Lab.,EERL71-05,Calif.Inst.ofTech.,Pasadena. Strong-motion earthquake accelerograms, II,corrected accelero-gramsandintegrated

velocity, anddisplacernent curves,withD.E.Hudson,.A.G.BradyandA.'ijayaraghavan, Earthquake Zng.Res.Lab.,EERL71-51,Calif.Inst.ofTech.,=Pa,sadena.

20.1971Engineering featuresoftheSanFernandoearthquake, February9,1971,ChapterII,editedbyP.C.Jennings,. Earthquake Eng.Res.Lab.,"ZERL71-02,Calif.Inst.ofTech.,Pasadena. 21.1972=Strong-motion accelerograms, III,responsespectra,withD.E.HudsonandA.G.Brady,Earthqua.ke Eng.Res;Lab.,EERL72-80,Calif.Inst.ofTech.22.1972Strong-motion earthquake accelerograms, IV,Fourierspectra,withD.E.Hudson,F.E.Udwadia,A.Vijayaraghavan, andA.Brady,Earthquake Eng.Res.Lab.,ZERL72-100,CalU.Inst.ofTech.,Pasadena. 23.1972Interaction ofashearwallwiththesoilforincidentplaneSH.waves,Bull.Seism.Soc.Amer.,62,63-83.24.1972Anoteoncorrection ofstrong-motion accelerograms forinstrument

response, Bull.Seism.Soc.Amer.,~62401-409.25.1972Stressestimates forSanFernando, California,"

earthquake. of9February1971:itineventandthirteenaftershocks, Bull.Seism.Soc."Amer.,62,721-750.26.1972Tectonicstressandsourcemechanism oftheImperialValley,California, ea,rthquake of1940,Bull.Seism.Soc.Amer.,~621283-1302.0-4 ~/0'ompaxison betweenambientandforcedvibration experiments, Int.J.ofEarthquake Eng.andStruct.Dynamics, ~l133-150.$",ud:esofstrongearthquake motionsandmicrotremor processes, withF.E.Udhvadia, 'International Conf.ofi>iicrozonation, Seattle,Washington. Analysisoferrorsindigitized strong-motion accelexograms, withF.E.Udwadia,andA.G.Brady,Bull.Seism.Soc.Ame'r.,o3,157-187.Anoteonscattering ofplaneSICwavesbyasemi-cylindrical canyon,Int.J.ofEarthquake Eng.and,Struct.Dynamics, ~1267-281.Characterization ofresponsespectrabyparameters governing the'rossnatureofearthquake sourcemechanism, 53VCEE,Rome,Italy.Recentdevelopments indataprocessing andaccuracyevaluations ofstrong-motion acceleration measurements, withF.E.UdwadiaandA.G.Brady,5V;CEE,Rome,Italy.--Ambientvibration testsoffull-scale structures, withF.E.Udwadia,577CEE,Rome,Italy.Comparison ofearthquake andmicrotremor groundmotionsinElCentro,California, withF.E.Udwadia,Bull.Seism.Soc.Amer.~63iso.4,1227-1253. Analysisofstron~earthquake groundmotionforprediction -ofresponsespectra,Int.J.ofEarthquake Eng.andStruct.Dynamics, Vol.2,No.1,59-69.TheFouriertransform, responsespectxaandtheirrelationship throughthestatistics ofoscillator

response, withF.E.Udwadia,Earthquake Eng.Res.Lab.,EERL73-01,Calif.Inst.ofTech.DampedFourierspectrumandresponsespectra,withF.E.Udwadia,Bull.Seism.Soc.Amer.,63,1775-1783.

Routinecomputerprocessing ofstrong-motion accelerograms, withV.Lee,Earthquake Eng.Rcs.Lab.,EERL73-03,Calif.Inst.ofTech.Characterization ofresponsespectrathroughthestatistics .ofoscillator

response, with1".E.Udwadia,Bull.Seism.Soc.Amer.,~64205-219.Athree-dimensional d'slocation modelfortheSanFernando, California, earthquake ofFebruary9,1971,Bull.Seism.Soc.Amer.,64,149-172.0-5 41..1974Parkfield, California, earthquake ofJuneZ7,'966:athree-dimensional movingdislocation, withF.E.Udwadia,Bull.Seism.Soc.Amer.,64,511-533.4Z.1974Timeandamplitude dependent responseofstructures, withF.E.Udwadia,Intl.J.ofEarthq.Engr..andStruct.Dyn.~2359-378.43.97AAnoteontheaccuracyofcomputedgrounddisplaceznents froznstrongmotionaccelerograms; withV..W.Lee,Bull.Seism.Soc.Amer.,64,1209-1Z19.44.1974Variations ofstrongearthquake groundshakingintheLosAngelesarea,withF.E.Udwadia,Bull.Seiszn.Soc.Amer.,641429-1454.

45.1974Scattering ofplaneSH-wavesbyasezni-elliptical canyon,withH.L.Wong,Intl.J.ofEarthquake Engr.andStruct.Dyn.,~3157-169.46..1974Surfacemotionofasemi-elliptical aQuvialvalleyforincidentplaneSH-waves, withH.L.Wong,Bull.Seism.Soc.Azner.,64,1389-1408. 47.1974Interaction ofashearwallwiththesoilforincidentplaneSHwaves:elliptical rigid-foundation, wthH.L.Wong,Bull.Seism.Soc.Amer.,~641825-1842. 48.1975Anarrayof.strongznotionaccelerographs inBearValley,California, withR.J.DielznanandT.C.Hanks,Bull.Seism.Soc.Amer.,~65l-lZ.49.1975Anoteonthedynamicresponseofrigid,embeddedfoundations, withJ.E.Lucoand'.L.Wong,submitted toIntl.J.ofEarthquake Eng.andStruct.Dyn.50.1975Onthecorrelation ofseismicintensity scaleswiththepeaksofrecorded, strongground.motion,withA.G.Brady,Bull.Seism.Soc.Amer.,65,139-162.51.1975Onthecorrelation ofseismoscope responsewithearthquake magnitude andModifiediviercalli intensity, .withA.G.Brady,Bull.Seism.Soc.Azner.,65,307-321.52.1975Astudyonthedurationofstrongearthquake groundmotion,withA.G.Brady,Bull.Seism.Soc.Amer.,65,581-626.53.1975Two-dimensional, antiplane, building-soil-building interaction fortwoormorebuildings andforincidentplaneSH-waveswithH.L..Wong,submitted toBull.Seism.Soc.Amer.0-6 Correlations ofpeakacceleration, velocityanddisplacement withearthquake magnitude,

distance, andsiteconditions, withA.G.Brady,Intl.Z.ofEarthquake Engr.andStruct..Dyn.(inpress).Onthecorrelation ofpeakaccelerations ofstrongmotionwithearthquake magnitude, epicentral distanceandsiteconditions, withA.G.Brady,Proc.U.S.NationalConference onEarthquake Engineering, AnnArbor,Michigan, 43-52.Preliminary analysisofthepeaksofstrongearthquake groundmotion-dependence ofpeaksonearthquake magnitude, epicentral distanceandtherecording siteconditions, Bull.Seism.Soc.Amer.(inpress).t.ullscale"three-dimensional testsofstructural deformations duringforcedexcitation ofanine-story reinforced concretebuildng,withD.A.Foutch,Z.E.Luco,andF.E.Udwadia,Proc.U.S.NationalCo'nference onEarthquake Engineering, AnnArbor,Michigan206-215.Anexperimental studyofgrounddeformations caused,bysoil-structure interaction, withZ.E.LucoandF.E.Udwadia,Proc.U.S.NationalConference onEarthquake Engineering, AnnArbor,Michigan, 136-145.Influence ofacanyononsoil-structure interaction, withH.L.AVong,J.Engr.Mech.Div.,ASCE(inpress).Antiplane dynamicsoil-bridge-soil interaction forincidentplaneSH-waves, withA.M.Abdel-Ghaffar, Intl.Z.ofEarthquake Eng.andStructural Dyn.(inpress).pAnoteontherangeofpeakamplitude sofrecordedaccelerations, velocities anddisplacements withrespecttotheModifiedMercalliintensity, Earthquake Notes(inpress).Contactstressesandgroundmotiongenerated bysoil-structure interaction, withH.L.WongandJ.E.Luco,submitted toIntl.Z.ofEarthquake Eng.andStruct.Dyn.Preliminary emoirical modelforscalingcourieramplitude spectraofstronggroundacceleration intermsofearthquake magnitude, sourcetostationdistanceandrecording siteconditions, Bull.,Seism.Soc.Amer.(inpress)..Dependence ofdurationofstrongearthquake groundmotiononmagnitude, epicentral

distance, geologicconditions attherecording stationandfrequency ofmotion,withB.Westermo, submitted toBull.Seism.Soc.Amer.0-7

~i~~65.1976Onthecomparison ofexperimental andtheoretical analysesoftheeffectsofsurfaceandsubsurface irregularities ontheamplitudes ofmonochromatic waves,withH.L.WongandB.Westermo, submitted toBull.Seism.Soc.Amer.66.1976Correlations offrequency dependent durationofstrongearthquake groundmotionwiththeModifiedMercalli. Intensity andthegeologicconditions attherecording

stations, withB.Westermo, submitted toBull.Seism.Soc.Amer.67.1977'ninstrumental comparison oftheModifiedMercalli(M.M.l.)andMedvedev-Karnik-Sponheuer (M.K.S.)Intensity scales,SixthWorldConf.Earthquake Engineering, NewDelhi,India.68.1976Effectsofcross-axis sensitivity andmisalignment onthexesponseofmechanical-optical accelerographs, withH.L.AVong,submitted toBull.Seism.Soc.Amer.69.1977Antiplane dynamicsoil-bridge-soil interaction forincidentplaneSHwaves,withAbdel-Ghaffar, SixthworldConference Earthquake Engineering, NewDelhi,India.70.1977Statistical analysisofthecomputedresponseofstructural

'response recorders (S.R.R.)foraccelerograms recordedintheUnitedStatesofAmerica,SixthworldConference Earthquake Engineering, NewDelhi,India.0-8 I~/JI~I'~~f'Ifls]i~orro~,~o~~*~s~l~~~~ATTACHMENT P~~REYIG'fOFTllE'SEIShlIC EYALUATION FOR~POSTULATED 7.5hfIlOSGRIEARTNQUA}:E, UNITSlAND2,DIABLOCANYONSITE'yJ.EnziqueLucoARcporttotheAdvisoryCommittee onReactorSafeguards U.S.NuclearRegulatory Commission. I~150hhy1978 REYIEIfANDRECONlENDhTIONS Afterdctailcdreviewofthcrcport'SeismicEvaluation forpostulated 7.5~ifllosgriEarthquake'Rcf. 1),.Ihavethcfollowing commentsandrccommcndations: l.Frcc-Field Desi.nSncctrum. Inmyopinion,thefrcc-fielddesignspectrumusedforrc-evaluation ofthcDiabloCanyonNuclearPowerPlantdocsnotreflectthestrongmotionatthcsitefora7.5magnitude earthquake atanepicentral distanceof5kilometers, butratherthemotionfora6.Sicearthquake atthatdistance. Thefree-field designspectrumdeveloped byNewmarkandadoptedbyNRCcorresponds toasimplified versionoitheaverageofthetwoPacoimaDamspectrarecordedduringthe6.5A'anFernandoearthquake withthehigh-frequency portionreducedbyuseof'n'effective'eak acceleration (Fig.1).ThcBluntsdesignspectrumdeveloped fortheapplicant closelyfollowstheNewmarkspectrum. Thepeal;acceleration, velocityanddisplace-I'entcontrolling thehigh,intc'rmcdiate andlowircqucncy portionsofthcNcwmarkdesignspectrumarcinagrccmcnt withtheaverage(50'ercentile) peakvaldcsobtainedbyTrifunac(Ref.2)forah6.5htearthquake whilefallingshortby40to60percentfromthecorresponding valuesfora7.5hfearthquake (Table1).Thepeakvaluesconsistent withthcNcwmarkspectrumarcalsoconsiderably lowerthanthose'suggcstcd inUSGScircular672(Rcf..3)asshowninTable'1.Inaddition, comparison ofthcNcwmarkandBlumcdc-signspectrawithcstimatcs ofthcavcragcrcsponscspectrumforqo~~~I~~P-2I ~n'~a7.5)4carthquakc asobtainedbyTrifunac(Rcf.4)alsoshowsdiffcrcnccs ofthcorderoi30to50pcrccnt(Fig.2).Theapplicant hasindicated thatthcthrustfaultmech"nism andthclocationofthePacoimaDaminstrument inthcSanFernandoearthquake mayhaveincrcascd thcrecordedpeakacccl-eration.Thesepossiblecficctsarcncgligiblc inviewofthcfactthatthestandarddeviation forpeakaccclcrations, whichhas,notbeenconsidered, corresponds toafactorof2.Also,thcrecordsiorthchfs=7.2Gazli,Russiaearthquake of1976indicateapeakhorizontal acceleration of0.8gatanepicentral distanceof10kilometers. Correcting forattenuation usingtheGutenberg's relationleadstoapeakacceleration of1.0gat5kilometers forthcGazliearthquake ingeneralagrcemcnt withtheresultsofTrifunacandthcUSGSrccommcndation (Table1).Xnviewofthesefacts,Imust,concludethatthcNcwmarkandBlumcdesignspectradonotcorrcspond tothegroundmotionfora7.5'arthquake atanepicentral distanceof5kilometers. Ipro-posethattheestimateoftheaverageresponsespectrumfor51=7.5,5kilometers, epicentral distanceandrocksitesofTrifunac(Rcf.4)bcusedasdesignspectrum. Thisspectrumisconsistent withthconlyrecordsavailablc forlargemagnitude andshortepiccn-traldistances (SanFernando, KoynaandGazli)aswellaswiththcUSGScircular672rccommcndations. 2~'Efi'cctivc'eak Acceleration. Ajudgmental iactorhasbccnusedtorcduccthc1.15gpeakaccclcration rccommcndccl inUSGScircular67toavalueoC.0.75g.Thisill-dcCincd CactorCP-3 ethasbccnusedinthcpasttoaccountfordiscrcpancics onthclevelofdamageobscrvcdascomparedwiththcprcdiction ofordinaryseismicanalyseswhichdonotaccountforthceffectsofsoil-structure interaction, arebasedonnominalvaluesfordamp-ingandstrength, assumelinearbehaviour a>>ddonotincludetheenergydissipation inpartitions andothernon-structural clc-ments.Thiscatch-all reduction factor.hasnoplaceinthede-signofcarefully analyzedstructures suchasthosexnnuclearpowerplants.Factorswhichmayreducetheresponseorthclevelofdamageshouldbeidentified andproperlyincludedinthcstruc-turalmodels.InthecaseofDiabloCanyon,manyofthesefactor.havealreadybeenincorporated inthcanalysis: useoftc-tstrengthratherthannominalvalues,useofhigherthancommon~dampingvalues,reduction byscattering ofwavesbylargefounda-tionsandpossibleinclusion ofductility. Thcarbitrary reductio.-. ofthehigh-frequency components ofmotionaffectstheresponsepipingandequipment. Irecommend the.elimination ofthisreduc-tionoftheinputmotion.3.OnthcEffectofScattering ofNavcsbRic.idFoundations. Thchigh-frcquc>>cy components ofthefree-field motionhavebeenreducedbythcso-called tau-filtering procedure toaccountbythescattering ofwavesbythcsupposedly rigidfoundations. Thiscorrection amountstoareduction oftheNcwmarkfree-field designspectrumby20to30pcrccntforfrcqucncics higherthan2cps.Slightlylowerreductions havebccnusedinthcBlumc'sspectrum. Thccorrection forfoundation scattering effectsisbasedonthc~~~~gP-4 assumption ofarigidfoundation andhorizontally propagating Sllwaves.Althoughthca"sumptionofarigidfoundation maybcrca-sonablc,itmustberccognizcd thatdeviations fromthcassumption leadtolocalized higherstressesinthclowerportionsofthcdiffcrcnt structures. Theassumption ofhorizontally incidentSflwavesishighlyquestionable considering thatthcepicentral dis-tancciscomparable withthefocaldepth.Underthcscconditions, thepossibility ofnearlyvertically incident.waves maynotbcruledout.Forvertically incidentwavesthescattering bythefoundations ispractically nonexistent giventhcshallowembed-ment.Assumingforthesakeoftheargumentthattheseismicexci-tationatthcsitecorresponds x~horizontally incidentSllwaves,Ifindthatthcreductions proposedbyNcwnarkandBlumcarctoohighwhencomparedwithanalytical solutions. Forhori"ontally incidentSllwavesthereduction ofthctranslational components ofmotioniscoupledwiththcpxistencc ofamarkedtorsional inputtothestructure (fordetailsrefertotheattachedpapers).Theapplicant hasincluded'accidental'ccentricities of5and7percenttorepresent thesetorsional effects.Theuscofaneccentricity of5percentcorresponds tothcuseofapeaktor-sionalacceleration atthcbaseofthccontainmcnt ofthcorderof0.025rad/scc2asmaybcinfcrrcdfromTable4-5ofPcf.'1.Thistorsional accclcration corresponds toatangential accclcr"ationatthcbaseofthccontainmcnt cxtcrior.of 0.025x70/52=0.05g.ThcresultsofRayandJhavcriofURS/131umc prcscntcd in ~P~Fig.56ofAppendixD39A,butnotusedinthcanalysis, showthatapeaktorsional acceleration ofthcorderof0.1rad/scccorrcs-2pondingtoapeaktangential accclcration atthcbaseofthccon-tainmcntexteriorof0.2g'wouldbemorcappropriate. Itmaybcconcluded thatthcuseofa5percenteccentricity undcrcstimatcs thctorsional inputbyafactoroffour.Thisob"crvationiscon-sistentwiththeoriginalworkofNcwmark(Ref.5)whichindicates thataneccentricity oftheorderof25percentwouldbcnecessary torepresent thetorsional effectsinducedbyhorizontally propa-gatingSllwaves.Itmustbementioned thatthcincreaseinpeakacceleration of0.2gbasedonamorerealistic estimateofthetorsional inputmorethancompcnsatcs forthcreduction bytau-filtering from0.75gtoO.G7gforthecontainment exterior. Fromthepointofviewofthcanalysisofthestructural re-sponsc,itdocsnotseemadequatetointroduce thetorsional inpu-thxoughtheuscof'accidental'ccentricities. Suchprocedure which)cadstothccouplingofthctorsional andtranslational rc-sponscinessentially symmetric structures distortsthcrcsponscandthcnaturalfrcqucncios ofthcsystem.Thceffectsofthctcr-sionalinputmaybcsignificant fo-theturbinebuildingin.whichthcpossibilit'y ofportionsofthestructure undergoing inelastic dcformations mayincreasethceccentricity. Ifitisshownthatthcseismicexcitation atthcsitecor-I'csponds mainlytohorizontally incidentwaves,thcreductions ofthctranslational andtorsional responseshouldbccvaluatcd onthcbasisofthcmorcexactmethodspresently availablc. To~~ includeancxaggcratcd reduction ofthctranslational motionwith-outincorporating thcfulltorsional cffcctsisimproper. Soil-Structure Interaction. InAppendixD-LL3AofRcf.1,thcapplicant presentsacomparison ofthcresultsobtainedbythefixedbaseanalysisoftheaxisymmetric containmcnt nodclwithtau-filtcredspectraasinput(F.B.Axisym.) withthoseobtainedfronasoil-structure interaction finiteclcmcntmodelwiththeNcwmarL;free-field motion(withouttau-filtering) usedassurface'control motion(PLUSl<-SSI). BasedontheresultsshowninFig.3A-1ofAppendixD-LL3A,theapplicant concluded that'thcuseoftau-filteredinputswithfixedbasemodelsasusedforseismicanalys"sofDiabloCanyonstructures isconservative.'his comparison isnotvalid,andthec'onclusion isnotwarranted bythcanalysis. Ioravalidcomparison, wemustrequirethatthefixedbaseaxis-ymmctricanalysisandthefixedbasePLUSllanalysisgiveesscntithcsameresponsecvcrywhcre exceptathighfrequencies whcrcthcfixedbasePLUSllresultsnot.irfcluding thctau-filtering shouldbeslightlyhigher.ThisisnotthccaseasshowninFig.3ofthisrcportobtainedfromresultsshowninFigs.3A-1and38-5ofAppendices D-LL3AandD-LL33.SincethcfixedbasePLUSllmod1is~inconsistent withthcfixedbaseaxisymnctric model,novalidconclusion astothceffectsofsoil-structure interaction canbeobtainedbycomparisons ofthctypebcmentioned thatithasbccnshownshowninFig..3A-l.Itmustthattwo-dimensional modelssuchasPLUSllmayundcrcstimatc thcrcsponscatthctopofthcstructure by30to50pcrccnt.P-7 ~4'InAppendixD-LL3B,comparisons arcprescntcd oithcrcsponscforafixedbaseandanSSImodelbothcomputedusingPLUS)landVthcNcwmarkfree-field spectrum(withouttau-fi3.tcring) ascontrolmotiononthcfrcc-surface. Assuminpthatthcresultsprcscntcd arcinternally consistent, itispossibletodrawsometentative conclusions. Fig.38-2ofAppendixD-LL38indicates that'hepca);accclcrations'n thecontainmcnt cxtcriorobt'aincd including thcSSIeffectsareapproximately 10pcrccntlowerthanthoseobtainedonarigidbase.SincethcSSIresult"automatically includethecffcctsofscattering ofwavesbythefoundation aswellastheci'fcctsofradiation dampingintothcsoil,it'aybeconcluded thatthereduction of20percent(0.75gto0.6g)bytau-effctproposedbyNewmar)'nd asimilarreduction usedbyBlumcarcnotconservative. Figs.3B-3and38-4ofthesameAppendixindicatethatthcstoryshearforcesandoverturning momentsonthecontain-mentexteriorobtainedincluding thcSSIareequalorslightlyhigherthanthoseobtainedfort)ierigidbasePLUS))model.Inthiscase,anyreduction ofthcfixedbaseresultsbytau-filtering wouldunderestimate thcstressesinthcstructure. Assumingthat.hePLUS)iresultsarecorrectandconsistent, itmaybeconcluded thatthctaureduction proposedbyHcwmar)-andBlumcovcrcstimatcs thcreduction effectsofwavescattering andsoil-structure interaction iorvertically incidentshearwaves.Znparticular, .thcstrcsscscomputedonthcbasisofspectrarc-duccdbytau-filtering wouldu>>dcrcstimatc thcstrcsscsthatrc-suitiromthcSSIPLUS)lanalysisbyatleast20pcrccnt.~I ~~4~~'~~-~~4~~~.~Theapplicant hasindicated thatthcshearwavevelocityatthesitecxcccds3600ft/scc.Thclow-strain anditcratcd'(orstraindcpcndcnt) shearWavesvelocities usedinthePLUSllSGImodelarenotrcportcd. Ircquostthatthisinformation bcmadeavailable. InAppendixDLL-15(Amendmcnt 53),aunifor'm.shearMavevelocityof3500ft/sec.'isused.Irecommend thatthetau-filtering approachbceliminated andthatacompletethree-dimensional soil-structure analysisforverticalandhorizontally incidentSHwavesbcundertaken. ThisapproachMillhavotheadvantage ofproducing realistic estimates of.theeavescattering andtorsional cffccts.ThepeakspectralresponseforthePLUSllfixedbaseanalysisoccursatafrequency of5.3cpsi~hilcthecorresponding frequency fortheaxisymmetric fixedbaseanalysisis4.5cps,indicating adificrence of18percent,. Ifthisdiffcrencc reilectsthoaccur-acywithWhichthcfixedbasefundamental frcqucncy canbccompu-Ited,thenitiiouldscornthatthepeakWideningofthefloorrc-sponscspectraof5percentonthchighfrcqucncy sidemaybcin-@sufficient. ThePLUSllSSIresonantfrcqucncy is18pcrccntlo:~erthanthePLUSllfixedbasefrcqucncy. Thisagansccmstoindicaethatthe15percentpoa1vidcningoffloorresponsespectraonthclowfrcqucncy sideisnotsufiicicnt. 5.SeismicI:iskAnalscs.Scvcralseismicriskanalysesfor'thcDiabloCanyonsitehavebccnpcrformccl. Thccstimatcs obtainedfortheProbability ofcxccdancc ofthcllosgridesignspectrumdif-X'crbytwoordersofmagnitude. Thcapplicant (Appendix D-LL11)P-9 ~~~~j~d~estimates thattIicprobability ofcxcccding an'cficctivc'ccel-erationof0.75gin50yearsisO.lpcrccnt.AndersonandTrifuna.(Rcf.5)cstimatcthatthcprobability ofcxcccding thchigh-,frcqucncy portionofthcllosgridesignspectrumin50yearsvariesfrom10to20percent,depending ontheseismicity modelconsidcre: Thcdifference corresponding toafactorof100to200canbcana-lyzedbyconsidering thcfollowing factors:(i)Theapplicant considers thcprobability ofcxccdance ofan'effective'cceleration of0.25gwhileAnder-sonandTrifunacuseasabasisofrefcrencc the0.75gHosgridesignspectrum. Theuscbythcap-plicantofan'effective'ather than'instrumental'cceleration of0.75greducesthcprobability ofex-ccdanccbyafactoroffour.(ii)ThcuscofBlumc'sSAW-IV'andSA~il-Vattenuation re-(iii)lationsasopposedtothcuscoithcTrif'unac's rc-lationsleadstoreduction ofthcprobability ofexccdance byafactoroft'en.Thcrestofthcdiffcrcnccs corresponding toaiac-torof2.5-4canbeattributed totbcdifierent'eismicity modelsconsidcrcd., llavxngisolatedthccausesofthcdiscrepancies inriskesti-mation,Iicilldiscussthemindetail.Ihaveindicated thatthc'reduction ofthcpeakaccclcration toan'cffcctivc'cvcl shouldnotbcusedinthcanalysisofnuclearpowerplants.Forthcpur-poseofestimating thcriskofexceeding thcllosgridesignspectrum, P-10 ftheanchoraccclcration of0.75ghouldbctreatedasactualpeak*acceleration. Inthiscase,thcprobability ofcxccdancc in50yearsasobtainedbyBlume'sanalysiswouldbcofthcorderof0.4percent(refertoTable11.S,D-L).ll)ratherthanO.lpcrccnt.Thcmainsourceofdifferences inseismicrisl'stimates canbcassociated withthctypeofaccclcration-magnitude-distance relationused.Thcapplicant's riskanalysisisbasedonthcuscoitheBlume'sSAhf-IVandSAl)-Vprocedure. Inmyopinion,thisprocedure leadstoaccelerations whichdonotreflectthestrongmotioninthenearsourceregionoflargemagnitude earthqua) cs.ISoneconsiders .thethreelargestearthquakes forwhichrecordswercobtainedinthenearsourceregion,oncfindsthattheob-servedpeakaccelerations arethreetotcntimeslargerthanthosepredicted bythcSAi~!IV-Vprocedure (Table2).Sincethcstandarddeviation forpeakaccelerations corresponds approximately toaSactoroftwo,itmaybeconcluded thattheSA'1procedure isnotvalidinthcnearsourceregion'of largecarthqua);cs. Table2indicates thatTrifunac's relations leadtoaccurateestimates ofthcobscrvcdpeakaccelerations (theaverageratioofobscrvcdtopredicted peal:acceleration is1.07).Fig.41-IoiAppendixD-LL41showsthatthcuscoftheSA~Iprocedure leadstoprobabilities thatarc10timeslowerthanthoseobtainedonthcbasisofthcTrifunac's. relations forthcsameseismicity model.Thc,scismi-toaprobilb11-ycalsoft)lcorderof4pcrccnt.citymodeldcscribcd inAppendixD-LLllleadsthenityofcxcccding apeal;acceleration of0.75gin50 ~g~~~~Thcseismicity modelusedinAppendixD-LLlli"basedontheseismicrccurrcncc relationobtainedbySmithforCentralCoastalCalifornia (Appendix D-LLllA).Theserccurrcncc relations arcbasedonthcseismicity duringthcperiod1930-1975 anddonotin-eludethc7.2H1927carthquakc inthcregion.Therccurrcncc.curves asshowninFig.11A-2ofAppendixD-LL11Aundcrcstimatc thcnumberofearthquakes withmagnitudes largerthansix,andarc~basedonanominalvalueforthcparameter bof0.92.Additional studybySmith(Appendix D-LL45A)indicates thatamoreappropri-atevalueforbwouldbeO.SS6.Theparameter bwhichcontrolstherelativecontribution ofthchighmagnitude earthquakes tothetotaseismicity hasa'trongeffectonthecalculated risk.ThcuscofbO.SS6wouldincreasethecalculated probabilities byafactoroftwo(r'cfcrtoTable45.3ofAppendixD-LL45).Thcseismicity modelconsidered inAppendixD-LL11isconsis-tentwiththcseismicity obtainedinAppendixD-LL41usi'ngthegeologicrecordoffaultdisloca'tion (a=3.12inD-LLll,a=2.SObasedon10yearsrecordanda=3.20basedon20x10years6recordinD-LL41).Theseismicity calculated onthcbasisofthegeologicrecordoflateralfaultslipdocsnotincludetheseismi-cityassociated >>'ithvorticalslipalongthcHosgrifault.Hamiltor(Appendix D-LL41A)quotesarcportbyEarthScicnccAssociates in-dicatingthatthc.'lateral slipwasprobablysubordinate tovcrtica)movcmcnt.'f thisisthccase,thcseismicity shouldbcincrcascd toaccountiorverticalslip.Considering allthciactorsmcntioncd, itsccmsthatthcP-12 ~~probability of10to20pcrccntin50yearsobtainedbyAndersonandTrifunacproperlyreflcctsthcseismicrisl'fcxccdancc ofthcllosgridesignspectrum. fv~~~~H.~t-vREFERENCES SeismicEvaluation forPostulated 7.ShfllosgriEarthquakc,Units1and2,DiabloCanyonSite,PacificGasandElectricCompany.*02.Trifunac, hf.D.,"Preliminary, AnalysisoithePeaksofStrongEarthquake hfotion-l)cpcndcnce ofPeaksonEarthquake hfag>>i-tudc,Epicentral DistanceandRecording SiteConditions," Bull.Scism.Soc.ofAner.,Vol.66,pp.189-219{1975).Page,R.A.,D.hf.Boore,ff.B.Joyncr,andH.fV.Coulter,GroundhfotionValuesforUseintheSeismicDesignofthcTrans-Alaska PipelineSystem,U.S.Geological SurveyCircular672,1972.4.Trifunac, hf.D.,"Forecasting thSpectra'1 Amplitudes ofStrongEarthquake Groundhfotion," Sixthli'orldConference onEarth-quakeHnginccring, NcvDelhi,India,1977.5.Ncwmark,N.hf.,"TorsioninSymmetrical Buildings," Fourth'forld "onfcrence.on Earthquake Enginccring, Vol.II,A-5,Santiago, Chile,1969.6.Anderson, J.G.,andhl.D.Triiunac, UniformRiskAbsoluteAcccler4ion SpectrafortheDiabloCanyonSite,Californi ARcporttothcAdvisoryCommittee onReactorSafcguards, U.S.NuclearRegulatory Conmission,

Dcccnbcr, 1976.'~~

llp~i~ii~,Ig~ThlSLEl.COMPARISON OX'AXIMUM GROUNDMOTIONSPeakvaluesusedby1Ncivmar.k0.75M=6.5Trifunac0.69(1.29)USCSNo.6720.9QM=7.5Trifu>>acUc,No1,07(2.00)v(in/scc)max23(48)3939(84)(in)8(19)1612(30)~~4'cxvmark, N.M.,"ARationale forDcrelopn>cnt ofDesignSpectraforDiab'.oCanyonReactorFacili(y," AppendixC,Supplcrncnt No.5,SER,Diablo~CanyonNuclearPov:erSta(ionUnits1and2,NRC,1976.Average(average'+ standarddeviation) peakmotionforrockatancpiccntral distanceR=7.5kmbscdonl'rifunac, M.D.,"Preliminary Analysisof(hcPeaksofS(ro>>gIart!iquakc GroundMotion-Dcpcndcncc ofPeaks.onEar(I]quake Magnitude, Epicentral Distanceandl<ccordi>>g Si(cCondi-tions,"B.S.S.A., 66,149-219(1975).~Page,R,A.,ctai.,"GroundMotionValuesforUseinthcSeismicDcign~ofthcTrans-Alaska PipelineSystem,"Geological SurveyCircular67?,1972,~~~~~~P-15 TABLE2.'ComarisonofRecordedandPredicted PeakAccelerations RecordedPeakAccel.SAWry-SA,4V(4)Predicted RatioPeakObserved/ Accel.Predicted Trifunac( )Predicted RatioPeakObserved/ Accel.Predicted 1971Pacoima()1967Koyna...i()1.25g0.63g0.80g0.12480.213g0.190g10.082.96-4.210.839g0.766g0.900g1.490.820.89.5.751.07(1)hf=6.5,epicentral distance3km,focaldepth15km.(2)h!6.5,epicentral distance5km,focaldepth5km(assumed). (3)hl=7.2,epicentral distance10km,focaldepth25.km..(4)~Ys12,000,62.04,y0(5)s2sp0.50' joosvVtlC7v~oV~So~A0ao5'~pdSl(EOdo'brOC~t~dO~pt4>rO~r<JIyIqlpoItlopoo.opO.oso.fo.,fFrequency, cps5lo~"0'Oioo~~~~8~~~F[Q.1-DESTGi45P"CTRUMCOMPARED71HHPACOMADAiVi.SP"CTRA,2PERCENTDAi&PPiiG, ~~g ~~3.02.5n~1.5~~e~0~~Dcgigll,5$CCft'll~Ifc0)(8LmsiicP,/%5).0.50.2.0,3o.97(sec.)a,"I,~~~~fQ:I-f~0~rrr..2-r.oacrAnr.".owot'v:::r.7t: At,Gttt:vt.s. ~r~~~~~A'0/DAC.POIlVIi%OPOFCCNIQ/NiHc:F7/lQQ/if+/~Q~~~r~85r0goJS40V0fo0~(8I~~I~,~)~~I)I~~~~~er~~)~~~~I~eI~=-I0lI~~~~IJii.I~i~~~IIt~rrIo~~Itft.fj!l~~j)I/I~~IrlfII~~~)Ia~twe}ilM~.PLUSH4~I~.i~I~I~~Il1~.'4~:~~\roreI)I,ssg'7"LUsH0.3(.o2.050lO/o0 1 ~~~Q~~~~~,)'TTlENT,()COetOV'rs ONSrISWICOLSIGMLEVELSFOl(DIABLOCAliYOihSITI!INCALII'OR'(IA by'.D.Vrit'uoac April,1973~~~ I~.3~~Thcfollowing convncnts dealwithseismicdesigncriteriaforthc\DiabloCanyonsiteinCalifor>>ia andrcprcsc>>t abriefsunnnaryofmyobservations a>>dprclitoi>>ary co>>clusio>>s whicha:cbasedo>>misccllancous writtenmaterialandona>>unbcrofmeetingsduringtheperiodstarti>>ginthcsummerof1977andendi>>ginAprilof197S.Infoxtnatio>> whichIhadoncertainaspectsofthiseffortmaybcincomplete. "Thegeneralpictureandthesummaries ofthccurrentstatusofthisprojectncvcrthclcss seem.adequateforthcfollowi>>g corrzc>>ts andrccomrtcndations. HuchhasbeenwrittenaboutdctailcdaspectsofseismicdesigncriteriaforthcDiabloCanyonsiteanditwouldb"impractical toaddressagainnun>crous pointsindetailandcompletely. Rather,IwillattempttopresentanoverallsunnnaryofwhatIbelicvctobeunresolved problemsatpresent,andwhatmightbcpossibleavcnucstoresolvethem.GeneralCommentsonthcCurrentIn)utsandCriteriaforSeismicDesinGc>>crally accepted<<ss(nnption appearstobcthatthcSSEonHosgrifaultoppositethcplantsiteshouldbcanhi=7.5carth-quake.Thistnag>>itudc, rcconnnc>>dcd byUSGS,hasbccndctcrmincd mainlyo>>thebasisofthcpossiblelc>>gthoffaultingo>>thcllosgrifaultsystem.2.Sincehl=7.5ata(lista>>cc of5-10kmfromthcsiteleadstolargepeakaccc3cratio>> (aboutlg)considerable efforthasbcc>>dcvot'c(l t.othca>>alyscsldll)charedesig>>('.(ltoshowthatQ-2 ~~~~theselargeamplitudes cana>>tlmaybcrcduccdthroug)tconsidcra-tionoft)tcfol)owing phc>>omcna: a)Scatt:ering anddiffraction ofhig)tircqucncy wavesfromthcfoundations oEdifferent plantstructures .hasbcc>>proposedasavchiclctojustifyreductio>> ofhighfrcquc>>cy spectralamplitudes (Tcffcct).Thcmannerinwhicltt:his.reducti.on hasbccnaffcctcdrcquircsunrcalisti.c assumpt:io>>s, forex-ample,thatfoundation isrigid.Themannerinwhicht)tisassumption isintroduced intoanal>sisifoftenon-sidedandconsiders mainlyonlyt)ioseconsequences oft:hcphysicalphe>>omena w)tie)tleadtoreduction.of spectralamplitudes. Othcxco>>sequences ofthisphenomcno>>, forexample,torsional androckingcxcitatio>>s offoundatio>>>>whic)t mayamplifythcostructural responsehavebeen,sofar,eitheroverlooked ortreatedinadcquatcly. T)tishasbeenachievedb>utilization ofdynamicmodelsfor'nalysis whicharesodeiincdthatonlyanincomplctc ph>sicsoftheproblem,i.e.,seismicexcita-tionandt)tcstructural

response, canbc.considered.

b)Thcterm"effective peakaccclcration" hasbccnintroduced suggcsti>>g tltatthcstructure will"sce"somcthi>>g smallert)tanactualpeakaccclcration. Thoug)tsuc)tapproachmaybcuscL'ulforcart,ltquakc rcsistcnt designofordinarystructures bymeansoit)icrcsponscspectrumtcclutiquc, thcterm"cffcc-tivepeakaccelcratio>>" ltasnotbccndcfincdi>>awaythat:would)c>>ablet)icderivation ofco>>sistc>>t resultsbyscvcral~~~~Q-3 diffcrcnt cxpcrtsinthcfield.Si>>ccthcproccdurcs forscalingRegulatory Guide]..60spectraarcbasedonmaximumvibratory groundacceleration" (asdcfincdinAppendixA)thisdeparture fromroutinedesignpractices makesitdiffi-culttocvaluatcthcnumberandthcnatureofthcconscqucnccs whichwouldresultfromsuchanapproach. c)Hypoccntral ratherthandistanceclosesttothefaulthasbeepusedtocvaluatcpeakandeffective peakacceleration. Thisassumption impliescertainanglesofapproachofseismicwaveenergy.Theseangleso'fapproachshouldthenbecon-sistentwiththcextenttowhich"reffect"isallowedtoinfluence thespectralamplitudes. Littleornoattention seemstohavebeengiventomutualconsistency oftheseassumptions andinsome.cases,inconsistent assumptions havebeenutilized. Forcxamplc,deephypoccntcr wouldincreasethedistanceatwhichpeakacceleration isevaluated, thus*reducingthcestimateofpeakaccclcrat'on amplitudes. Thiswould,however,alamoimplythatthewavesarrivetowardsthcfoundation almostvertically. Inconsideration of"Teffect"howcvcr,horizontal dimensions offoundations appeartohavebccnusedimplyinghorizontal incidcncc ofwaves.d)Thclargedampingequalto7'ohasbccnadoptedfordynamicrcsponsccalculations. Thoughthcapparentdampingforthccomp)ctcsoil-structure system,subjcctcd tocarthquakc excitation ma>bcmuchlargertluin7"',inadcquatc basishasbeenpresented tnjustify7.;danglinginstructural systems~~,Q-4"~'l~ '4lonly.Sclcctio>> oftoolargestructural dampingcoupledwithonlytwo-dime>>siona1 orsimplethrcc-dimcnsio>>al analysisofsoil-structure interaction canleadtou>>rcliablc rcspo>>scestimates. 3.Atleastthrccseismicriskstudieshavebccnprcparcdtocstimatcthcprobability ofcxcccding thesclccteddcsig>>criteriaatthcDiabloCanyonsite(Blumc,Anga>>dNc>>mark,A>>dcrso>>andTrifunac). Thesestudieshaveproducedresultswhich,insomecases,differbyasmuchastwoordersofmagnitude. Concurrent >>iththecom-parisonsofthcscstudies,. considcrablc cfiorthasbccndevoted.todiifcrcnt detailsinthemethodology emplo>edinthesecalcula-tions.Littleornoexpliciteffortanddiscussion hasbccnde-votedtothemodelsofseismicity whichareessential inputintosuchcalculations, evc>>thoughthismayrcprese>>t thcmostimpor-ta>>tcontribution tothcdiscrepancies amongthcresultsofdiffcrcnt studies.I>>someextrcmecases(c.g.,reportbyBlumcand)'iremidjian) claboratc workhasbcc>>carriedout,apparently invain,toshowthataparticular methodforscalingpeakacccl-cration(Trifu>>ac, )976)supposedly leadsto"toolarge"estimates ofpeakacccleratio>> irrcgardlcss oithcfactthatthoseresultsofTrifu>>ac(1976)have>>everbeenusedanddonotrcprcscnt abasisforthedcrivatio>> ofseismicriskmodelsbyAndcrso>>. a>>dTrifunac. InthcrcportbyA>>ga>>dNcwmark,substa>>tially smallertha>>averageseismicity hasbcc>>assumed>>car, thcsite.Thismayleadtoa>>u>>dcrcstimatc ofLctualrisk.~~~~~Q-5I C~ERecommendations A.Groundhfotion.'.Dctcrministic approachbasedonthcassumption thatanearthquake oCmagnitude )f=7.5orgreater>>i]1occuroppo-sitethcplantsiteshouldbcre-cvaluatcd. Thismagnitude mightbeanindicator ofthccxtcntofgeologicfaultingphenomena butitisnotnecessarily thcmostrcliab)ebasisforevaluating thenatureofstrongshakingclosetothefault.Therearcnumerousexamplesinliterature ofsig-nificantdifferences between)I<and))S,forexample,>hicharcbasedonshortandlongperiodseismic>>aves, respectively. Oftenstudieshaveshownthatlargerearthquakes maybcthoughtofasasequenceofseveralormanydiscreteevents>>hichcansequentially tal'eplacealongalongfault.Finally,I'helargestrecordedacceleration, sof"r,hasresultedforh)<6.5only.Forthcscreasons,andfromthcdesignvic>>-point,I>>'ouldprcfcrtoadopt)I=6.5onHosgrioppositethcsiteandnothi=7.5.2.Near-field sourcetheory(notafiniteelementorfinitediffcrcncc modelofthcsourceanditssurroundings) couldbeusedinconjunction withthespectralanalysisofstrongPmotionsrecordedcl..cwhcre tocvaluatctheamplitudes ofresponsespectraindcpcndcnt oC.peakaccc)cration estimates orofseismicrisk<<nalyscs. G.~lies>on.".c:h1.Three-dimcnsio>>al soil-structure interaction analysisshouldbccarriedout.'I'hissi>ouldbedoneassumi>>gthatthcfrcc-fieldresponsespectrafordesignresultfromi>>cidcntSII,SVorltaylcigh waves.ForSl}andSVexcitation, horizontal, verticaland45incidcncc a>>alysisshouldbcconsidcrcd. Thisapproacl> wouldofferthcfollowi>>g advantages: a.The"veffect"ifprcscntwillbcaccou>>tcd forcorrectly. b.Torsional a>>drockingcxcitations willbeincludedi>>totheanalysi.s correctly. c.Theproximity ofthecartIiquakc sourceandthcfactthat~thewavesmostlikelyarrivehori"o>>tally willbcaccounted forcorrectly. d.Thcradiation dampingi>>thcsoilwillbeintroduced intoanalysisproperlysothatthchighvalueof7'orstruc-turcswouldnotbcrcquircd. L'xccptforthcfactthat7'odam}ii>>gispcrmissi}ale accordi>>g tothercgulati>>}', }',uidc].61,thi>>highstrucfur>>l darn})i>>g rccollllllcnded forthcseismic>>>>>>lysis attl)cDial)loCa>>yo>>.sitehas>>otI)ccnjustif-iedd.Forcedvihr>>lio>> test(avai1>>l>lci>>t}.S.a>>il.1>>p>>n)data,whereflicetlect.ofsui}-structure i>>ter>>etio>> <<>>diliIfere>>tmodeofcncr},)i>>I~>>ti>>totl>estructure pluri>>},n>>ex/crime>>t, relativetoi>>eide>>t. <<:>>tl<>>>k~w>>vv."is>>ot>>econ>>ted I'ur,maybcoflitt]cus()>>rs'}al>I1,'sl1L>>}',.LI'l.>>e(l}>>ILI>>mI)I>>}}>>~(rueturusa>>lltht1jcompo>>e>>}, sIorsclsmte'I'csI)0>>!4c c>>Icul>>C10>>s.Q-7 I,pC'yI' ATTACHHENT R"IF.~BgUNITEDSTATES~DEPARTl)ENT OFTHEINTERIORGEOLOGICAL SuRVEV-ESTIYiATION OFGROUNDi~OTIONPARAMETERS DavidH.Boore,AdolphA.OliverIII,RobertA.Page,andWilliamB.QoynerOPEN-FILE)REPORT 78-509PreparedonbehalfoftheNuclearRegulatory Cormission Thisreportispreliminary andhasnotbeen.editedorreviewedforconrormity ~vithGeological Surveystandards. yggoGlCAL gg~,~~ggi.opARicJUi'l2197SLl0RAG" ~\m'I~2fh~'4I'~I.v'I<hqoake.ThesolidMnesshowthe70percentpredonintervalforthe'aqua>>tude7.1-7.?datasetofthisreport.thostofthepointsinthatdataet~~-.g9>>u~',>camefromthemagnitude 7.7KernCountyearthquake. Theamountofdisagreement showninFigures47and48isnotsurprising ~jviewofthedifferent assumptions, differentmeasuresofdistance, and"vs~~~~'djfferentdatasetsusedinarrivingatthedifferentcurves.The1djsagreement is,asmightbeexpected, thegreatestatshortdistances.ESTIMATION OFPENPARAMETERS AT'HORTDISTANCES 6eneralcomments. Theregression linesgiveninaprevioussectionofthis\reportprovidethemeansforestimating peakgroundmotion'parameters atdistances greaterthan5kmf'rmagnitude 5.0-5.9earthquakes, atdistances j.greaterthan15kmformagnitude 6.0-6.9earthquakes andatdistances greatervthan40kmformagnitude 7.0-7.9earthquakes. Unfortunately, mostoftheFdaniagefromearthquakes canbeexpectedtooccuratshorterdistances.. Attemptshavebeenmade,asdescribed inthepreceding section,toprovide%11yC.r.'~'-rmcurvesforestimating atshorterdistances. ForreasonsgiveninthePreceding sectionwedonothavecompleteconfidence inthosecurves.Mewillnotventureourownsetofcurves,butwilldiscussbrieflysomeoftheconsiderations bearingongroundmotionestimates nearthesource.Furtherdiscussion ofthesequestions ingreaterdepthisgivenbyBoore(1974).Therehavebeenanumberofstudiesusingsimplified modelsofthefault;ing processtosetlimitsonthegroundmotionatthefaultsurface(Housner, 1965;Ambraseys, 1969;Brune,1970;Ida,1973).Brune's(1970)nearsourcemodelassumesthatruptureoccursinstantaneously overthefault 'IIpeatparticieve1otyisproportional tothestsdropandn')pile.aquas>00cm/secforastressdropof100bars.Thepeakacceleration isinfiniteqfallfrequencies areincluded, butiffrequencies above10Hzares~filteredoutoftheacceleration pulsethepeakvalueis2g.Thisisausefulmodelforrelatinggroundmotiontothephysicsoftheruptureprocess,'utitdoesnotgivefirmupperlimits.Anargumentcanbemadeforlarger~tionsifonetakesrupturepropagation intoaccount(Ida,1973;Andrews,1976)..Furthermore, thepeakvaluesofgroundmotionmayrepresent localized hihstressdropsasHanksandJohnson(1976)havesuggested forpeak19acceleration. Suchlocalized stressdropsmighteasilyexceedonekilobar...:":-..', Thepeakacceleration atthesurfaceislimitedbythestrenothofnearsurfacematerials ashasbeenpointedoutbyAmbrasey(1974).Forsitesnearthesourceunderlain bysoilmaterialoflowstrength, thisfactormaycontrolthevalueofpeakacceleration. Thisconsideration mayalsoapplytorock'~~sitesiftherockissufficiently weathered. Determination oftholimitingacceleration, however,wouldrequirereliablemeasurement ofthedynamic,inh~k.situstrengthofthesoilataparticula'r site.Intheabsenceofadequatemeasurements onemustpresumethattheacceleration couldbeatleastaslargeas0.5g,whichwasrecordedonathickness ofmorethan60metersof'ater-saturated alluviumatstationnumber2intheParkfield earthquake \(ShannonandWilson,Inc.andAgbabianAssociates, 1976).~~Inthecaseofpeakdisplacement, aspointedoutbyTrifunac(1976),ifeI,oneassumesnoovershoot, thepeakislimitedtolessthanonehalfthestatic>slocation amplitude. Thelatterisknownformanyhistorical earthquakes >>dmaybeestimated asafunctionofmagnitude (BonillaandBuchanan, 1970).Theaccelerogram recordedatPacoimaDamduringtheSanFernandoR-3 \<earthquake hasmajorsign%>cance fornearsourcegroundWotion estimates. Theinstrument islocatedonly3kmfromtherupturesurfaceatarocksite~~erethetopographic reliefissevere.Thepeakrecordedhorizontal Iacceleration is1.25g,velocity113cm/sec,anddisplacement 38cm.Thisis1~mtpeonlyaccelerogram everrecordedwithin5kmforanearthquake ofmagnitude aslargeas6.4,andassuchoughttohavestronginfluence onestimates ofnear-source groundmotion.Thepossibility oftopographic amplifica ionneeds,consideration. Atwo-dimensional finite-difference studyby'Boore(1973)suggeststhattheacceleration mayhavebeenamplified byasmuchas50Percentbutthatth'evelocityanddisplacement wererelatively unaffected. Giventheseconsiderations, itwouldbedifficult forustoacceptestimates lessthanabout0.8g,1'IOcm/sec,and40cm,respectively, forthemeanvaluesofpeakceleration, veloc'td'~em~ttrocksiteswithin5kmoffaultruptureinamagnitude 6.5earthquake. Merecognize thatthesenumbers~iepresent oneearthquake withaparticular focalmechanism andthatestimates areboundtochangewhenmoredatabecomesavailable. >lepresumethatthe~P.~ss.statistical scatteraboutthemeanwillbeatleastasgreatforthenear-insitesasatthegreaterdistances wheredataisavailable. Theaccelerograph atPacoimadamwasonly3kmfromthenearestpointonmt'herupturesurface,butthenearestpointwasnotthesourceofthepeak>>tions.Asnotedpreviously thesourceforthepeakvelocityandforthePeakacceleration aredifferent pointsontherupturesurfaceseparated byPerhapsasmuchas20km(Hanks,1974;BouchonandAki,,1977). ~.Abovemagnitude 6.5thereareessentially nodataforestimating theeffectofmagnitude onnear-fault peakacceleration, velocityand4isplacement, otherthanthestaticfaultoffsetdividedby2asaboundon II~\~~~..~hg/,thepeakd~spaoement.Conservatism requiresthepresumption orsome[noreasewrathmagnitude-HanksandJohnson{1976)presented asetofpeakaccelert'ataat.sourcedistanceofapproximately 10kmforearthquakes inthemagnitude range3.2-7.1.Theonlydatapointabovemagnitude 65wasforthimperialValleyearthquake of1940whichtheyassignamagnitude of7.1incontrasttoourvalue6.4,sothedatasetcanbeappliedtomagnitudes greaterthan6.5onlyasanextrapolation. Thedatasetshowssomedependence ofpeakaccelerations onmagnitude, butHanksandJohnsonarguethatthedataareconsistent withtheideaofmagnitude-independent sourceproperties. Thedataplottedasthelogarithm ofpeakacceleration againstmagnitude canbefitbyastraightlinewithaslopeequivalent toanincreasebyafactorof1.4permagnitude unit.Thisshouldnotbeusedforextrapolation beyondccgnitude 6.5,however,becausethedatasetwasdeliberately chosentorepresent relatively highvalues,andthustheslopeofthelinefittingthedatamaynotbethesarneastheslopeofthelinerepresenting meanvaluesor,for.thatmattero,ofthe11nerepresenting valuesforanyfixedprobablity.'.-.':-At sitesotherthanrocksitesaccelerations mightbelessbecauseofthelimitedstrentghofnear-surface materials, but,aspreviously noted,determinin hogwmuchlesswouldrequ>redynamic,in-situmeasurements ofsoilproperties. Theamplif~cation ofpeakvelocityatsoilsitescomparedtk~'sites:may notbesogreatclosetothefaultbecauseoftheenergylostinnonlinear soildeform*eformatlon, butnumb:.ical modeling(JoynerandChen,1975)demonstrates thepossibility ofamplification ofvelocitybyasmuchas30<<entevenundercond)talons ofintensedeformation. Thepossibility ofgreateramlificatpioncannotbeexcluded. Anplification ofdisplacement ato<1sitesshouldbeexpectedclosetothefault,-asatgreaterdistances, if .~thesoilcolumnissufficiently thick.ACKNOWLEDGMENTS WearegratefultoR.P.Maleyforassistance inobtaining information 0nstrongmotionrecording siteconditions andtoA.G.Bradyforunpublished'trong motiondata.R.B.Natthieson, T.C.Hanks,andA.G.Bradyreviewedthemanuscript andsuggested improvements. lI~"\~1('1)~'h'~~I~g\~~PC~\1'I+~;'.ZI'~~R-6}}