ML20147C268
| ML20147C268 | |
| Person / Time | |
|---|---|
| Site: | Vallecitos File:GEH Hitachi icon.png |
| Issue date: | 09/29/1978 |
| From: | Treby S NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD) |
| To: | Baldwin W FRIENDS OF THE EARTH |
| References | |
| NUDOCS 7810120019 | |
| Download: ML20147C268 (38) | |
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NUCLEAR REGULATORY COMMISSION D ROOy-
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W. Andrew Baldwin, Esq.
j Legal Director h
'S Friends of the Earth e
124 Spear Street San Francisco, California 94105 4
y In the Matter of General Electric Company (Vallecitos Nuclear Center - General Electric Test Reactor, Operating License No. Tr-1)
Docket No. 50-70 (Show Cause)
Dear Mr. Baldwin:
This letter is in response to your August 29, 1978 request to Mr. Chris Nelson of the NRC Staff that a copy of the Staff's draft report on carthquake potential at the Vallecitos Nuclear Center be sent to you and all parties to this proceeding.
I note that you are counsel for a party admitted to this proceeding and that at the current time all parties are engaging in discovery upon one another. In these circumstances, I advise you that all requests, whether formal or informal, for information or documents from the NRC Staff should be directed to the Staff Counsel.
The Commission's Rule of Practice specifically exempts working drafts from those NRC re ords and documents which are to be disclosed and made avail-able for inspection and copying in the Commission's Public Document Room.
10 CFR S 2.790. Ilowever, in response to your informal request of August 29, 1978, and in a spirit of cooperation, we are enclosing a copy of our draft report entitled "Show Cause Proceeding Safety Evaluation Report Input, GE Test Reactor Site /Vallecitos Nuclear Center" dated August 17, 1978. It should be noted that this draft report has been made available only to the Staff's constfltant, the United States Geological Survey, and has not previously been released to the
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public.
I wsh you to have a clear, understanding of the status of the a closed draft repor t. Neither the NRC Staff technical reviewers, nor the NRC management, offer the draft information as completed Staff work which fully represents
9 r the views of the technical reviewers or management. To the contrary, the technical reviewers and management expect to make substantial changes in the draft material to reflect the results of the presently on going Vallecitos site geological investigations.
In addition, while the draft informaion reflects the approach that was being taken by the NRC Staff at the time that GE notified the Staff that further site investiga-tions would be undertaken, and may be informative to others on that basis, there is no reason to believe that the Staff's final approach and conclusions must be fundamentally the same as those set forth in the draft information.
. Sincerely,
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s;w)id Stuart A. Treby Assistant Chief Hearing Counsel
Enclosure:
Show Cause Proceeding Safety Evaluation Report input cc w/ enclosure:
Edward Luton, Esq.
The Hon. John L. Durion Mr. Gustave A. Linenberger California Department of Health Dr. Harry Foreman Advisory Committee on Reactor The Hon. Ronald V. Dellums Safeguards Ms. Barbara Shockley Atomic Safety and Licensing George Edgar, Esq.
Board Panel Jed Somit, Esq.
Atomic Safety and Licensing Mr. Ken Wade Appeal Panel Mr. Edward A. Firestone Docketing and Service Section The llon. Phillip Burton Mr. J. Devine
'I mlr, n &7 Afhls.h tl' U., u * ) W Show Cause Proceeding Safety Evaluation Report Input GE Test Reactor Site /Vallecitos Nuclear Center August 17, 1978 1.
BACKGRO'UND_
In July 1977, the Geosciences Branch was requested to perform a review of the geology and seismology aspects of the General Electric Conpany's application to renew the Operating License of the Cencral E1cetric Test Reactor (GETR) at Pleasanton, California. As part of the documen-tation for the license renewal application, the General Electric Con pany (CE) submitted reports on the geology and seismology of the site and vicinity (UES/Jolin A. Blume,1973a; URS/ John A. Blume,1973b; Engineering Decision Analysis Company, Inc. (EDAC), 197 6). Preliminary review of these reports caused the staff to become concerned that a potentially serious safety situation existed at the site which had not been adequately defined in the licensce's submittals.
Specifically, the staff recognized that the GETR is located within an active tectonic environment about 2 kilomet ers cast of the Calaveras f ault zonc and about one kilometer south of the Williams f ault as mapped by Hall (1958) ; and, as shown in the licensee's report (URS/ John A. Blume, 1973a), a lineation passed directly-through the plant site. The existence of the lineation caused the staff to become concerned that a potential existed for fault offset beneat h lhe GETR ritruct ures. Uc met with GE on August 4, 1977 and made them aware of our preliminary findings and of the scope of investigat.f on that we considered would be neccesary to conservatively evaluate the earthquake aud fault hazards at the site.
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On August 22, 1977, NRC received a copy of the U. S. Geological Survey (USGS) open-file report number 77-689 (Ilcrd,1977) which contained an interpretation of the geology of the Livermore Valley, California, including the area of the Vallecitos Nuclear Center. A new geologic map which accompanied the report placed a fault (thn Verona fault) immediately adjacent to the CETR. The position of t.hc Verona fault as mapped by 11 erd'(1977) coincides with the position of the lineation shown in the GE license renewal submittal and is about i
one kilometer south of the Willians f ault as mapped by Hall (19.58).
USGS personnel met with the NRC staff and GE and its consultants on August 31, 1977.
At that. meeting Dr. Ucrd reviewed the geologic evidence for the Verona fault.
In response to that meeting, GE subsequently excavated two trenches across the mapped trace of the Verona f ault. On October 21, 1977 GE reported to the NRC that its geologi. cal consultants had identified evidence of faulting in both trenches.
Mr. Hofmann and Dr. Jackson of t.hc NRC and Mr. Morris of the USGS inspect.ed the trenches on October 22, 1977.
Our inspection confirmed the existence of a low angic plane c,f movement across which near-surface beds are offset. Uc concluded that this plane could be a low angic thrust fault which, based on the evidence then availab'le, could be capable within the meaning of Appendix A to 10 CFR Part 100. As a result of these findings, and in consideration of the potential for a large earthquake on t he nearby Calaveras f ault which could cause ground motion exceeding that for which the facility was denigned, an Order to Show Cause why the facility i
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should continue operation was issuel'y the Commission on h
October 24, 1977.
GE responded to the Show Cause Order on November 11, 1977 with a report which argued that an ancient landslide is present and that the '.4 slide accounts for the low angle shear plancs observed in the trenches.
Consequently, GE argued that the existence of the Verona fault is
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unsupported by the availabic data. After reviewing this report we met with GE and its consultants and informed them that the report did not adequately explain the evidence for faulting near the GETR. Ue stated further that we believed an extensive investigation and approximately 18 months to two years of review and interaction would be required to completely assess the geology, scismicity, and geotechnical engineering aspects of the GETR site as would be required for renewal of the license.
We also indicated that investigations necessary to. determine whether or not the Verona fault exists near the GETR and,.if so, whether it should bc considered capabic within the meaning of Appendix A to 10 CFR Part 100 would he of critical importance.
CE was also provided with several request.s for additional information.
On December 16, 2977, (letter, R. W. Dartnizel to V. Stello) GE took the follow]ng position with respect to the Show Cause Proceeding:
"while we (CE) strongly believe that the Verona f ault does not exist, G.E. has agreed to hane our analysis and modifications on two non-mechanistic condit ions which are:
a) peak ground acceleration oi' O.8g from the Calaveras fault b) a surface offset of 1.0 meters as a result of a hypothesi.~ed low angle thrust fault near GETR."
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' Since that time, GE has continued to acquire data and modify the exist-
.ing mapping and geologic interpretations of the site area and region.
We and our advisors, the USGS and the U. S. Army Corps of Engineers (COE),
accompanied on several occasions by personnel from the California Division of Mines and Geology (CDMG), have made visits to the site and vicinity to examine the results of investigations.
In addition, we have received two review letters from the USGS (letter, P. llanshaw to U. Gammill, Jan-uary 30,1978 and letter H.
Coulter to E. Case, March 31, 1978). We have also received memoranda from the COE (letter, T. Krukjian to J. Stepp, January 10, 1978) and from the CDMG (letter P. Amimoto to J. Stepp, October 28, 1977 and letter, P. Amimoto to J. Stepp, December 29, 1977).
In addition to the field trips and meepings at the site and at the NRC Bethesda of fice, we have received a number ~of reports e i addenda from CE l
relating to its inv'estigations of the geological, geotechnical and seismic aspects of the site and vicinity. These reports are:
'1) " Seismic and Geologic Investigations for the General Electric Tent Reactor Facility," July, 1973, URS/ John A. Elume Associates; (2) " Seismic Analysis of the Reactor Building for the General Electric Test Reactor Facility," July, 1973, URS/ John A. Blume Associates, Engineers; (3) " Evaluation of General Electric Test Reactor for Operating, Environ-mental, and postulated Accident Conditions," June, 1976, Engineering Decinion Analysis Co. Inc.;
(4) "Responne to MRC Order to Show Caune dated 10-24-77," November.11, 1977, Gcneral Electric Lor'pany; m___________.._.__
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, 1 (5) " Seismic Criteria and Basis for Structural Analysis of Reactor Building, Attachment 1," December 16, 1977, Engineering Decision Analysis Co., Inc.;
(6) " Geologic Investigation General Electric Test Reactor Vallecitos, California, Preliminary," January, 1978, Earth Sciences Associates;.
(7) " Geologic Investigation General Electric Test Reactor Vallecitos, California," February, 1978, Earth Sciences Associates; (8)
" Geologic Investigation General Electric Test Reactor Vallecitos, California, Addendum I," April, 1978, Earth Sciences Associates; (9)
" Draft Seismic Risk Analysis for General Elcetric Nuclear Center Pleasanton, California," December 5, 1977, Tera Corporation; (10) " Determination of Vibratory Loads to be Combined with Fault Dis-placement Loads," March 1,1978, Enginecting Decision Analysis Co. Inc.; and (11) " Geologic Evaluations of GETR Structural Design Criteria Reports 1, 2, and 3," March, 1978, Earth Sciences Associates, e
We have reviewed the data provided in these reports, Our conclusions and the supporting bases contained herein represent our assessment, based on currently available data, of the carthquake vibratory ground motion, faulting and landslide hazards at the GETR site, i
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a i..>p c:a tid d II, Current Staff Position The information available at the present time leads us to conclude that:
(1) This evaluation represents our finding with respect to the Show Cause Proceeding. The information developed for this site does not meet the investigative requirements of Appendix A to 10 CFR Part 100.
Additional investigations which will be needed during a license renewal' effort are not specifically addressed in this evaluation.
(2) Geologic data are indicative of a fault (the Verona fault) passing through the GETR' site, and this fault should be assumed to exist.
(3) The Verona fault should be assumed to be capable within the meaning of Appendix A to 10 CFR Part 100 and, therefore, to pose a potential for surface faulting near or beneath the reactor site.
(.4) 2.5 meters of net slip at the surface resulting from reverse-oblique movement along a fault plane which could vary in dip angic from 10 to 60 degrecs provides a reasonably conservative description of surface slip en the postulated Verona fault during a single event.
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f N ! L.:.! h.i.; J U (5) Maximum vibratory ground motion at the GETR site would result from a magnitude 7 to 7 1/2 earthquake centered on the sector of the Calaveras fault nearest the site.. Acceleration peaks at the free-field surface could be slightly in execca of ig.
(6).The horizontal vibratory ground motion at the GETR site result-ing from an earthquake of magnitude 6 to 6 1/2 centered on the Verona fault could contain acceleration peaks as high as Ig.
However, the overall level and duration of-shaking would be less than for a magnitude 7 to 7 1/2 earthquake centered on the Calaveras fault approximately 2 kilometers from the site.
The effective value of acceleration to be used as a scaling parameter for Regulatory Guide 1.60 to describe the seismic design basis ground motion at the GETR site for this' event will be evaluated by Dr. N. M. Newmark.
(7)
Combined loadings caused by fault offset at the surface and peak vibratory ground motion must be considered to act simultan-cously because there is no reasonable way to forecast:
a) The location of rupture initiation, the mode of rupture propagation and the potential source area for radiated seismic energy, b) The location of possible fault asperitics or other localized bea. ck inhmtogeneities which may control peaks of strong i
ground motion.
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-8 c) The sequence of possible interaction among the Calaveras, the Verona and the Las Positas faults.
In view of the above and the virtual absence of near-field records of strong ground motion for larger earthquakes, there is insufficient evidence to support the proposition that peaks of a strong ground motion and offsets'from surface rupturing will be separatec' in time.
(8) The availabic evidence suggests that the large landslide com-Icx north of the GETR facility is inactive and poses no hazard to the plant.
III. Discussion 1.0 Geolog 1.1 General The staff's geology review has been concerned with defining the earthquake sources in the site vicinity and evaluating the potential hazard of faulting and landsliding at the site. The CETR site is located in a highly active tectonic environment (Bolt and others, 1977;
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Lee and others, 1971). Physiographically the site is within the Vallecitos Valley cection of the larger Livermore Valley.
Coologi cally both of thene valleys lie within Livermore cyncline and the central part of the Coast Ranges structurally related to the San Andreas fault syst.cm, a transform fault which forma a major sector of the boundary between the llorth American and Pacific lithospheric plates extending from Cape l'endocino to the Gulf of Calif ornia (Anderson, 1971). Diffeien'.lal i;ovem n! c er oc.o thc lithor.pher ic pl atet rcrena this boundary is npparently occuring at 6.tu t 6 cm/yr with
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the Pacific plate moving northward relative to the North American plate.
This movement results from a regional orientation of the maximum principal stress that is approximately north-south horizontal (hnderson,1971).
The sector of the San Andreas fault system in the vicinity of the San Francisco Bay consists of the main San Andreas fault and two, perhaps three other major mesbers. The casternmost of these is the Cal ~averas fault zone which passes about 2 k11ometers vest of the CETR site.
Geologic and geodetic data (Rogers and Nason, 1971; Radbruch, 1968'; Thatcher, 1975) indicate that the Calaveras fault is moving in a right slip sense (rock mass on 'he west t
side of the faulting being moved northward relative to rock mass on the cast side of the fault). We consider the Livermore syncline and the major structural elements therein, including faults,.to owe their existence to movement across the Calaveras fault. The faults significant to our review which we consider genetically related to the Calaveras are the Las Positas fault, which trends approximately northeast-southwest across the Livermore syneline, and the Verona fault, which as interpreted is a low angle thrust within the southern flank of the syncline. The Greenville fault, which may also be considered a member of the San Andrens fault system, lies about 16 kilometers cast of the GETR site (Herd, 1977).
1.2 Verona Fault In response to the Show Cause Order dated October 24, 1977, CE has submitted a ntmiber of geologic reports. The report entitica, " Geologic Investigation of General Electric Test Reactor Site, Vallecitos, California," dated February 1978, and Addcndum I dat ed April 1978, compiles GE's inve ;tigat ions and summatizen and n:'dificu carlier conclusions.
With renpoet to (N existence of the Verona fault and the potentfal for surface faulting in the.
site area thin report concludes:
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"This investigation has disclosed several lines of evidence which indicate that neither the "Verona fault" nor any other active or capable fault exists in the vicinity of the GETR."
This conclusion by GE is based primarily on the following interpretations:
(1) Evidence presented for the existence of a fault is either erroneous or can be explained more easily by other geologic processes.
(2) The thrust offsets or shear features observed in trenches 1 and 2 and in the large diameter borehole result from large scale land-sliding.
(3)
Continuous mappable stratigraphic units around Vallecitos Valley-preclude the existence of north-or northwect-trending faults which postdate deposition of the Livermore age gravels.
(4) A north-side up thrust fault is inconsistent with the structural and stratigraphic relationships in the Livermore Valley.
(5) The regional tectenit framework indicates that the Livermore l
Valley region is in an extensional stress environment which argues against development of, or movement on, a thruct fault.
(6) The similarity and centinuity of landforma and crocional surfaces between the Livermore Valley and Vallecitos Valley preclude significant faulting in the GETR site area.
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' The thrust of GE's response to the Show Cause Order ith respect to the question of surface faulting is that the Verona fault as postulated does not exist.
Investigations and information to date have increased our understanding of the site geology and have produced evidence for large scale landsliding in the site vicinity.
The f ault of.fset found in the excavated trenches could have been caused by this landslide, llowever, GE has not undertaken investigations necessary to resolve this question. Moreover, the existence of a landslide near the site does not in any way preclude the existence of faulting there. As dis-cussed below, evidence for faulting exists in areas away from the land-t,lide area. In fact, landsliding often results from oversteepening of slopes due to fault movement and ceismic shaking. Ue conclude that sufficient Investigations have not been accomplished to date to show t. hat faulting does not exist in the plant site area. This conclusion is based on the following observat. ions:
(1) Offsets observed in trenches 1 & 2 may be due to novements on a thrust fault or to movement of a large scale landslide.
Suf-ficient investigations have not been undertaken along the proposed fault trace in areas where landsidding definitely does not exist to the northwest and to southeast of t he GETR site for us to assess the presence or absence of faulting.
Areas to the northwest of the GETR show, both in t he field and on aerial photonraphs, the presence of geolonic features which are indicative of the exist ence
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Steeply-dipping Livermore gravel beds are truncated along a linear to curvilinear topographic escarpment. Along the base of this escarpment are a number of sceps and springs.
(2) To the southeast of the GETR, the geologic log of the La Costa i
tunnel (California Department of Uater Resources,1966) suggests low angic faulting and folding in an area th' rough which the post-ulated Verona f ault would pass if projec'ted castward.
In the same general area there is e, major abrupt change in the strati-graphic section above.the middic conglomerate unit of the Livermore gravels when compared to the section to the north of the GETR.
This change can be explained either by the presence of a thrust fault or by an unconformity. Presently, it is cicar caly that this area is otructurally complex and these obccrvations could be judicat.ive of post-Livermore gravc3s faulting.
(3) The relationnhip between the Verona fault and the Las Positas fault has not been investigated and the area of the Uilliam's f ault (llall,1958)-La Costa tunnel intersection has not been investigated sufficiently to permit a satisfactory interpretation of the structurc in that critical area (see above). Understanding this relationship becomes important in attempting to synthesize a tectonic model for f ault development and fault. movement in the Livermore valle.y.
Arcas of int ersection or merging of faults can be in a transitional stress state which usually leads to the development of fault patterns which are geologically complex such as en echelon faulin rather than a cingle pinnar fault ourface.
Suc h comp]ex p::t t erns are dif ficul t to interg :t without ext enn]vt finL1 invi:,tJgation,.
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l jj (4) A prominent south-facing scarp and topographic breck does exist in the cite area. To ascribe the origin of this scarp solely to macs wasting and crocion is not supportable based on the availabic data.
That is, fault movement explains these features just as well as crosional processes.
(5) Exist.ing geologic maps and texts o'f Vickery (1925), Hall (1958), Prince (1957), Uns/Blume Associates (1973), and more recently Ucrd (1977) support the existence of the Verona fault and other faults in the GETR site area and vicinity.
In addition, t.o the northwest of the CETR site and along the general northwesterly projection of the Verona fault is the northwest-trending Pleacanton fault which is identified as a pot entially active f ault on the California Division of Mines and Geology Special Studies 7,ones Map, Du.blin Quadrangle'(S3osson, 1974).
Several authors (Burkland and Associates, 1975; Judd Hull Associates, 1977; Carpent.cr, 1977) have assigned various locations to the Pleasanton fault.
At the present time, it is reasonabic to conclude that the Pleasanton fault is a possibic continuation of t he Verona fault.
(6) Recent scismological studies of earthquake fault plane solutions indicate that-the Liverriore Valley region is in northeast-southwest comprecsion (Simila and Somerville, 1978) and not extension as argued by the licensee.
Morever, this indirect observation of the st ress direction is consistent with the highly active regional tectonic framework.
Northea s t-sou t huc. s t compression would support.
developteut of, and continued movement along, a northeast-dipping y
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14 thrust fault such as the Verona fault.
If extension were occurring in this area, stresses would not be likely to cause the develop-ment of, or movement along, a northeast-dipping thrust fault.
(7) The ages of geologic units in the site area have not been determined.
Of special concern are the ages of offset units observed near the ground surface in the trenches.
As discussed later, such a determination is absolutely necessary in resolving the origin of the offset ob-served in the trenches.
(8)
Critical elements of the arca geologic mapping are still in question evidenced by a Continuing discovery and interpretation of.tcC-88 tonic deformation within t.he Livermore gravels with the increased acquisition of field information. The nore recent geologic mapping provided by GE contains substantially more geologic structures than the earlier versions, indicating more post-Livermore tectonic deform-ation than would have been ascertained from GE's earlier mapping.
(9) Photo 11ncars and the cause of seeps and ponds to the south of and in close proximity to the GETil site area have not, been trenched or explained.
In tectonically active areas photolinears are often due to groundwater barriers or differential erosion due to the l
presence of a fault.
(10) Questions concerning tim relat ive stratigraphic position of Liver-more gravel nnd younger stratigraphic units to the north and south of t he postu]ated Verona f ault have not been reco1ved. Without such otratinrephic informat Jon it jr not pomlble t o deter:,ine tbnt beds hn.
not beca di:.placed vc rLically.
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e the origin of the offsets in the trenches has not been resloved.
Evidence which favors a large landslide includes:
(1) pho tointerp re-tation of landforms and oblique overflight pho'tographs, (2) the jumbled nature of subsurface materials, and (3) the presence of rotated blocks and shear surfaces as observed especially in t.rench 2 and along the avine near trench 2 northwest of the CETR and (4) soils may be dated at an age when more humid climates were known to exist in the site area.
A serious question with regard to,the landslide versus fault origin of the of f sets in trenches 1 and 2 relates to the age of the offset soil units.
This has not been determined.
If the landslide is older than the offset soils, then the observed thrust features must be attributed to some other more recent mechanism s'uch as faulting.
The data currently available do not resolve the conflicting interpretations of geologic features in the site area (e.g., topographic scarp, linear features, springs).
One interpretation is that faulting is the primary ge let i' cause of these features.
This interpretation has been put forward by a number of geologists whc have uorked in the site region [Vickery (1925), Hall (1958), Herd (1977)] and by the URC staff.
An alternate inter-pretation hu been of f ered which would att ribute the cause of the f eatures in the s-ite area solely to erosion and mass vasting. This interpretation is supported h'y data interpret atiohs made by CE's consul tants.
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present time, sufficient data have not been provided to reco1ve there con-flict inn int erpretat ions. For the Show Cause proceed 16g the licencee has, t heref ore, chosen to as sume that a surface offset of I r:eter could occur a s ti renalt of t:nvenwnt on a hypot hm:iwd t brunt fault.
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- 16 1.3 Surface Fault Offset On December 16, 1977 [ letter, R. W. Darmitzel (GE) to V. Stc11o (HRC)], GE stated that a hypothetical offset displacement at the ground surface of 1.02 meters on a 15 degree shallow-dipping shear plane would be used to analyze the effects of surface rupture e
on the GETR structure. This hypothetical fault displacement is based on an empirical relation of maximum surface displacement to total length of surface rupture (Earth Sciences Associates, 1978). The licensee accumes 8.2 kilometers for the total length of the Verona fault. Utilizing data from Slemmons (1977), the licensee developed a plot of surf ace displacement versus rupture length for known faults. Utilizing a maximum rupture length in a single event of one-half the total mapped length or 4.2 kilometers for the Verona, a maximum surf ace displacement of 1.02 meters was estimated.
The liccusee considers this to be a very conservative value becauce the data set includes large faults along crustal plate boundaries.
Uc have concluded that a poctulated 2.5 meters of net slip resulting from reverse oblique movetuent along a fault plane which dips from 10 to 60 degrees provi_deo a reasonably conservative description of cu face clip on the postulated Verona fault during a single event.
Our judgei..ent is 1
I based, in part, on our understanding and evaluation of observationa of fault s offsetc made following t he 1971 San Fernr.ndo, California earthquake (Earrous and othere, 1973).
The Verona fault, including it : northuc> t erly projec t Ion along possih3 e opinyt, of L'
f t bc P3.u.snut en fault, l' a ' on ent i mted rurfno 1 canth of 12 kil o--
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,'.,J a by or merging with the Calaveras fault to the northwest and by joining with, or being truncated by, the northeast trending Las Positas fault in the general area of the La Costa tunnel. We believe that utilization of the San Fernando data is a reasonabic basis for postulating the amount of offset that could occur on the Verona fault near the GETR because of simil a ri ty.
The length of observed surface rupture during the San Fernando event was about 12-15 kilometers. Movement was predominantly in a thrust sense with a substantial horizontal component. Assuming the Verona fault ruptures along ito estimated trace, it would have a rupture 1cngth of about 12 kilometern.
Based on observations of a reverse thruct move-racnt in the trench excavations near GETR and regional stress considerations which would support crustal compression (Lee and others, 1971), we would anticipate the Verona fault to undergo reverse movement as did the San Fernando aren faults.
In addit. ion, due to the orientation of the. regional stress, the Verona fault should be expected to have a horizontal component Of moVelitenL.
In support of our judgement, we used tuo approaches to analyne the available information on reverne and reverse-oblique f ault movement.
Uc firnt analyzed 3 79 observations of vertical surface of f sets that oc-cured during the San Fernando carthquake as compiled by Barrova and
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othera (1973).
This analysis indicates that the mean of the observed vertical throw on n given fault break to have been about 34 centinetern
(.34 metern).
Of the.179 obnervatioon, 97% uure lov than 1 neter and c: c<ed"d 1 ter.
The : min.u-rt Le : 1 t h!,
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offnet unted wh kh exceeded 1 ta ter f: 160 c ent h clers (1.6 rrt er s).
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, One meter of vertical offset exceeds the mean plus two standard deviations for the San Fernando data.
Observations of offsets in excess of the above values either reflect releveling which travere ed some distance and several f ault of f sets or are not slip calculations (resultant of the dip-slip and strike-slip movement). The mean value of t.hc horizontal movement would be about 40 centimercra (.4 meters).
Six of the 40 hor-izontal taovement observations noted equalled or exceeded 1 meter with the maximum being 190 centimeters (1.9 meters). Using one meter of vertical throw, one meter of horizontal movement, and 55 degrees as an average dip, uc obtain 3.57 meters as a conservative representation of the average net slip along the fault breaks.
Such a statistical data interpretation must be viewed cautiously because consideration has not been given to possibic bias in the data used in our evaluation.
For exampic, we have not analyzed how many measurement were made on a given break or if the authors had a bias touard more acasurements on cmaller or larger breaks.
Bonilla'and others (1971) calculated slip vectors along an assumed fault plane in the Orange Grove k.enue and Eighth Street areas that sustained surf ace rupture during t he 1971 San Fernando event. These calculations indiente that 2.4 meters of net slip displacement took p] ace.
It is also noted that vertical displacenent for this location is distributed across a zone of breakage 200 metern wide which is complicat ed by a zone of shear-ing and thrusting and a zone of extension. At the present time, ue do not have a compilation of direct. neasurements of net. ulip on individual norfsco ropture,
e.
r_
i; n.,
b u
ll i
, l In order to provide further information on possible fault dicplacement, we used the approach of Slemmona (1977) and EDAC (1977) which relates maximum surface displacement to length of surface rupture. For purposes of this analysis the Verona is accumed to be a reverse thruct fault with a rupture length of 12 kilometers as discussed previouc3y.
Slemmons (1977) performs an analysis which deve? ops a best straight 'line fit to fifteen data points of reverne and reversc-oblique-slip faults.
For a rupture length of 12-15 kilometerk as observed af ter the 1971 San Fernando carthquake, tnis relationship would predict a maximum net-slip value of 1,66 to 1.83 meters.
Actual net-slip observations at San Fernando indicate that the maximum net slip was about 2.5 meters.
Utilization of the relationship developed by Slemmons (1977) would have under estimatcd the maximum dinp3acement by about 0.8 meters for a 12 kilometer rupture length. Using cit.her a log normal distribution or the Student's t distribution, which may be more appropriate for small data sets, and the general technique of Mark (1977), ve obtain an exceedance probability of 26-30% for 2.5 ueters, of net slip.
That is, there is 70-74% confidence that the mulmun displacement value predicted for a 12 kilometer surface rupture vill be encompassed by the 2.5 meter value, it to cicar that this worldwide data set for reverne and reverse-obliquc-clip faults in nm11' and har, a wide variation in values.
Because of this fact, t he above obaerval ion cannot be used in a rigoroun sense with a high 3evel of confidence.
L'o do believe, however, th,t the nboce analyet do provide furt her nopport of our judg ment.
./ ? 3 7! !:"(lp
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Baced on the above conciderations, we conclude that 2,5 meters of net clip at the surface resulting from reverse-oblique novement along a fault plane which could dip 10-60 degrecs provides a reasonably conserva-tive description of the magnitude of offset that might be anticipated as a result of movement on the Verona fault during a single event.
The USGS indicated in their letter of January 30, 1978, that considering the fact that the San Fernando earthquake produced 2.4 meters (7.9 feet) slip, the one meter of net-alip movement postulated by CE does of net not seem to provide adequate conservatism.
We have considered the recommendations of the USGS and our present ppsition takes into account thoce views.
2.0 Lando11 ding 2.1 General This section addreusca the contention that there is evidence for a 3nrge landslide complex northeast of the' GETR site, evaluates the future movement, stabilit y of t.he pont ulated 3 nndslide compicx against and discunnen the potential for surficial failures.
The crent of the northwest-trending hills (Rocky Ridge) immediately northear.t of the tajor building complex at GETR is at au clevation of about 1,200 feet.
The toe of the southwest f acing hillside in at about el evat t on 600 f eet. Near the GETR, the drop in elevation from the ridge (clevnt ton 1200 f eet) to the toe (clevation 600 feet) is typ!cally 600 feet. The lorJ: or.t al dist ance from the rJde,e to thn toe varier, from 2,800 f ut t o 4,800 f eet and in typically 3,600 With a vertical drop of 600 iert and i lar.!zontal di.1,nce of 3lNO feet, thc crerage clope in 6 bori::ent al to 1 vertical.
w,
, '4',
_arge handslide compicx_
2.2 L
d U 2.2.1 E_vi d enc e The detailed topographic map, Figure 14, of the Geologic Invesigation by Earth Sciences Associates (1978b) for the GETR provides the config--
uration of the hillside slopes northeast of the GETR complen, In addition to the canyon aidewalls, three separate slope conditions can be identified from the ridge crest down to the toe of the hillside.
l Relatively steep (1.7 llorizontal to 1 Vertical) amphitheater scarplike areas can be identified between about elevation 900 and 1,100 feet.
~
The central portion of the slopes is characterized by a relatively flat bench area typically between elevation 900 and 950 feet. The toe of the hillside benches below elevation 900 feet consists of noderately steep slopes, typically 3 horizontal to 1 vertical.
The horizontal length of each of these areas is typically 1000 feet for the toe.
The above con-ditions combined with the bulboun, lobate-shaped toe of the slope are cuggestive of old landslide deposits.
Evidence that the couthwest facing hillside north of the GETR site con-tainn a large 'ar islide complex can be identified on high altitude' infrared air photos (Eart h Sciences Associates,1978b) of the hill f ront.
The high al titude phot on c1carly show a scarp-like f eature two-thirdn of the way up the southwest facing hillside and the lovaltitude photos clearly show a nearp-bench-toc configuration frequently associated with large landslidee Shear planes and low angle thrunt features were identified in trenche-(T-1 and T-2) and borings (Bil-1, L!I-2 and Bll-3) loca t ed near the basc of t he hillsJde (Ref. Fin
- 7. Ea r t h Sc ience' /.< noc i a t ea, 1970b).
In
- r r ial s o, m r e r.' Jn t ren'h 2 wre j uW ee' addition, cab au f.m e s
nheared.
Tliese featurer, aie t ypically ob:.crved at or near the toe of a landalide.
'l r :,.;,
l c
- 22 Shear planes and icw ant c thruct features were identified in trenches i
(T-1 and T-2) and borings (B11-1, B11-2 and Ell-3) located near the base of the hillside (Ref. l'ig. 7, Earth Sciences Associates, 1978b). In addition, subsurf ace caterials observed in trench 2 were jumbled' and sheared. These features are typically observed at or near the toe of a landslide.
Although the shear planes and low angle thrust features identified in the trenches and borings can be interpreted to be landslide features, we cannot rule out fault offset as the source of these features. Detemining the age of the youngest offset in trenches 1 and 2 is an itaportant consideration in the evaluation of the large landslido complex. The age of the youngeat offset in trenches 1 cad 2 has not been documer.ted adequately. This point must be resolved before any adequate exp10. nation of the origin of thoce offsets can be deteruined.
2.2.2 po,mi bi n Ori g i n Several condit ions have been postuint ed by the licensee (Earth Sciencen k nociates, 1978b) to kve influenced forration of the landslide corapicx, 1,arge lando11 des of thir type in tbn Coast Ra n g c e, of California have. been int erpret ed (F:irt h Sciener s Anroc !at eo, 1970e) to have occurred at a l
th.ie when:
(1) climatic conditions s.'re wetter; (2) nea 1cvel stande were l o uce r ; (3) Coast Range canyons were considerably steeper; and (4) crosion ratnu were much Licher.
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23 -.
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We agree that the hillside was probably cteeper and higher before any landslide occurred and steep slopes which are subject to high precipitation rates have a high probability of experiencing landslides. Toe crosion as postulated by the applicant would further increase the landslide potential. The occurrence of all or cost of these conditions concurrently in the past could have caused the formation of the large landslide complex northeast of the GETR and we conisder the liccusee's interpretations to be reasonabic. However, to evaluate this hypothesis, the age (s) of movement (s) along of fsets observed in trenches 1 and 2 must be determined and correlated with the history of past environmental. coaditions.
2.2.3 Relative Stabili1v_
The stability of the landslide complex northeast of the GETR site depends on the driving force due to the weight of enterials within the hillside conplex, the strength of the geologic materials, and the influence of the groundwater conditions on both the resisting and driving forces, A qualitative evaluation of the stability of the complex at the pretent tine can be made by cenparing the current conditions with thore under which the complex was believed to have forrced aad assessing ev:!dence from field observations.
The priert y evidence cupporting the relative stability of the large landslida cog lex in that the postulated lanAlide mass and headocarp area have been T.rently modified by erosion. This hn served to stabilize in over,!
itx.
First, erosion ch.mnels which disne-t the slid the tut pt af u e fm ef fic iat dr i,
'f
<1'd: W i:.
T1. e dr 1- - e p[ n;, e fl ici at d:,i n y;c
,rattm ca the sur f ac e of the d ide tini:.ze,
24 infiltratica of water during concentrated winter rains. This enhancec the relative stability of the casa because (1) reduction of strength due to pere water preocures within the landslide rmss is minimized and (2) the weight of water contributing to the driving force is minimized.
Second, the deep crocion channels obcerved on the slide mass also indicate that much of the original landslide material has been removed from the landslide cc:uplex. This has resulted in a decrease of the potential static driving force thereby enhancing relative stability.
Some of the materials creded fro:o the slide cmss continue to be deposited as alluvial fans along the bacc of the hill front and serve as a minor buttreca fill to lupede movement of the slide.
Other evidence supporting the relative etability of: the large landslide compicx is the exintence of the broad flat bench. The postulated landslide compicx is assumed to consint of one or ceveral rotationni block f ailures.
These types of f ailures of t en result in adjustr:ents of slope.profilec to form benches sin!1ar to thoce observed in the landalide comp 3 ex.
Bench formatica reduces the gravity driving force act.ing on the block thereby increaning relative atchility.
Haced upon the conditions lint ed above, we believe that a rot ational block failure node in nant reasonable for t he pontulat ed Jaudo.lide compl ex and tlnt the slopea have adjusted to enimuce t he reJ at ive stab 31.i ty of the f ailure nass.
4 g
25 7,,
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4 2.2.4 Staff Position Daned on our evaluation of the available information, it in the staff's opinion that the hillside north of the CETR site is a landslide compic:: which has become stabilized.
We consider reactivation of the landslide highly unlikely under the environmental conditions anticipated during the life of the plant.
Additional data regarding (1) headscarp boundaries, (2) lateral limits of the slide, (3) identification of slip curfaces and bedding within the slide mass, (4) age dating of youngcat offset, and (5) quantitative stability analyses will be required to conffrm the above conclusion during the detailed safety review for licente renewal.
^
2.3 of Many small, shallow landslides occur in the hilln northenst GETR.
Most of there surficial landslides include debris slides, bank caving and slumping, and earthficus' involving coil, col]uvial deposit n, and older landslide debric.
Shallow landsliden of the typen rent!eued are comcon on t a/ crate to steep slopen in the Conat Ran y,c a. They gcnurally occur or are reactivated during the winter taanths.ch.,n precipitation in the area is highest. Their formaticu and t eac t-t va tica in influe:ced predor.Luautly by (Eart h Sc 3 enter Ancociatea, 197Eb) :
(1) the derrec of. slope, (2) concentratien of precipitation (3) thick-of rail and colluv!al deposita, (4) draina"y characteristics of ucer t he surficial materJalo, and (5) rcr wa3 of toe support.
26 i,
~
The licensee has stated that the largest of these failures han a plan area of about 1 1/2 acres and a maxinua thickness on the order of 4 to 5 feet.
In general, the su:all landslide deposits are less than about 5 feet thick but locally are reported to be as much as 20 feet thich or core.
The earthflows and debris slides are believed to fail episodically with only ninor downhill novement during a given event. Movement is generally believed to be slow although short surges of a few tens of feet have been reported. Ihny carthflows stabilize before reaching the base of the hillside on which they originate.
Miuor slumping and bank caving are ecuman along the oversteepened tanks of poorly consolidated unterials such as t hoae near the site.
The tass of ::aterial involved in these failu'res is relatively small and slump debris is tradually washed dcun the channel during seaseaal cencentrations of precipitation.
Uc expect that thtne relatively tinor slope proccascu will continue to be nctive in the hills northeast of GETP as lotu; as prescat e t tvi r ettren ' al 1
1 condit ions persist. Houever, bcsed 0:. our review of surficial land-sliding in the clea, it is the staff's judgement tFnt it is high]y railure taste - will recch or pese a thrent unidi:ely that any of these to the CET"
27 -
3 l v.. )g o'
),-
3.0 Seisnology 3.1 Scistaic Design Basin The neismic design hazards for the GETR site include vibratory ground taction, f ault off set at the surface hencath the unit and vibratory ground taction combined with surf ace of f set caused by postulated move-ment on the Verona fault.
The licensee has provided an evaluation of thece design hazards in reports by EDAC (1976, 1977) and has provided additional supporting discussion in a report by Earth ilciences twoociates (1978d). The ntaff has reviewed these reports and has taken account of the analyses and cone]usions contained in them in the preparation of thic testimony. This testinony is concerned with an evaluation of the nature and magnitude of the hazards of f aulting and ground motion at the site.
3.2 Vibratorv Groural Motion The CETR site ic located in a complex fault environment 2.3 ki3cneters eact of the Calaveras fault, direcity over the projected surface trace of the postulated Verona f ault and within 3 kilometers of the Las Positas fnult. The licensee's evaluation of vibratory ground motion at the GETR r.it e f u given in EDt C (1976 and 1977).
The evaluation considered both recto c enre probabilitien of eart hqu;&: intensit.y at the nite and taximum earthquakes on the San And rean, lhycard and Calm / eras fau2tn (CDAC, 1976).
The liccarce concluded th a t a valuc of Lorizontal ground acceleration of 0.56 n i n t i e approprJate effective value to he used to scale Rec,u l a t o r y Culde 1.60 spect ra as the se i s: te desi;,n ba: 1, vibratory ground not ion
}
,f 4f at the CETR site.
This conclusion is based in part on an assumed tr.aximum earthquake of inagnitude 6.5 on the Calaveras fault.
In a later report the licennee adopted a seismic design basin vibratory ground mot:f on described by a reaponse spectrum having the chape of Regulatory Guide 3.60, but with amplificalion factors ccaled to 0.8g f or the GICR site (EUAC, 1977). This dcaign basin van put foruard by the licencce in response to preliminary indicationn of the level of conservaticta that might be accept able to the URC ntaf f and concultanto, The licennee continues, however, to support 0.56g as being the proper reference acceleratden for the site and conciders this value to properly reflect l
the v.ibratory ground motion huard there.
i l
l We consider that the potential earthquake:, sources that are important in ascenning the vibratory ground motion hazard at the GETR site are the Calavnran fault, the Las Positas fault and the Verona f aul t.
Ib x-iraum carthquakes for t hc oc fau1LL would have magnitudes of 7 to 7'1/2, 6 to 6 3/2 and 6 to 6 1/2, renpectively.
A magnitude 7 to 7 1/7 carth-quake is ent i::nt ed for the Calaveras f ault.
Strike-slip faulte nub-cidiary t o una connM: red to the S :n Andru f aul t have gener ated u.m-itaum ear thquakes of r.rrnit ude about 7 to 7 J /2 ba:-:d en the data of Co f fi:.au.md Von Hake (1973).
As previously discunccJ in the geo l o g;,
section, thc proposed Verono fault can be presum: d t.o exist beyond t he bou
of t he.4rea r.apped by Ferd '.nd to riei re wi t h the Cal v :n: f aul t.
Th i r.
< rumpt ion yieldr t ot al lengt h o f.:hout 12 hij o: tiers.
Until a
evidence to thc (ont.rary ic for t hc alug, it ont be presu :d that the
~,
6,
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6 29 -
Verona fault in structurally connected to larger faults, and that n tmjor port Ion and posnibly all of t.he 12 kilometers length could rupture during a.cingle earthquake.
It in our conclusion, therefore, that the San Fernando cart b uake of 1971 could be considered as an carthquake l
similar in cize to a potential event on the proposed Verona fault.
A larger earthquake (magnitude 8 to 81/2) could occur on the main San Andreas fault, but due to its dintance from the GETR site, approximately 50 kilometers, such an event would result in 1 css serious ground motion at the site than would be caused by the pot ential events dcrcribed above.
The GETR site in located 2.3 kilouctern cant of the Calaveras fault, about 3 kilometern vest of the Las Positas f ault and uithin the fault zone of the postulated Verone fault.
The level of ground motion hazard from the Las Positas in enveloped within the ;;round motion har.ard f rom the Calaveras fault since the anximum expected earthquake on the Las Positan fault i s less t hr.n that on the Cnlaverac fnuit and it is inore dictant f rom the CETR sit e.
Simi.larly, a aund motion from the postulated Verona ', mid be with in t hat f ror. t.he Ca} avel as fault.
The Gr.rR qite is vj t hin t he near r.ourco region of both f aults whc re attencatinn of nource encry; it conoidered negligtble. Tho,1 bra t ory preun3 mot ion huard
,t t he site can t here f ore, be cons idered t o renuit fro a ma;ritudi 7 to 7 J/2 earthquate on the Calaverct fault.
invol'. eJ in i at imat ing ea t t hqun '- ;round 1;ut, rous corapl er 13 t ier re motiour an a
.ite.
At di nt. n: m grmter t l.a n ch at ?n FiJoi ': m fn' il ih r<1(i., u a b i
1 At dis,tance, cJm cr to n.
~<e, L.
t i, e
. i
- s 3
l l
A l
l 1 l
Ja relatively small. There is, in fact, a virtual absence of records l
of strong ground motion for locations close to large carthquake sources.
Any estimate of free-field ground notion at the GETR sit.e must, therefore, he considered an extrapo3ation of data rather than supported by direct ob r,erva t i on s.
Simple source theory indicater, t ha't peak acceleration near t he causative fault taay be proportional 'to the stress conditions s
and rock physical properties at the source, possibly independent of eart hquake magnitude (nee for example Brune, 1970).
Limited observational dat a t.end to support t.hese theoretical results (IIanks and Jonhcon, 1976).
1)uration of tootion, ine]uding duration of high penkn in, however, a f unction of eart hquake r:agnitude or source size.
The level and durat. ion of acceleration near z.o carthquake cource have been evaluated based on the aval.lable dat a by 1' age and othen; (1972).
Their study indicates t ha t peak horfrontal rear-source acceleratJon for a magnitude 7 to 7 1/2 eart hquake could exceed 1g and t hat the total duration of nt rong motion
~
could be betwen 25 and 4 0 secondr.
The ntaff considers these values a pp rop t ic:l for desc r i.b i n,n the vJhr :t ory ground t ation hazard at the Gi:TP. si t e due t o a na;;n i.t ude 7 to 7 ]/2 carthiuake centered on th-Calas er;u f,.n1 t at a distance of 2.3 kilomet ors.
la, aucc of t he pa ta n t J ::1 presence of the Verona fault bmenth tbe.. ! t u,
c: mbined Joad!ac, u nt be connidi t ol f i rm bot h orf ace o f f r et and t he p o n hn o f v i l a a t o r y p, co o nd mo t i o't. k'hil e Jt is pornible that the pens irturinr.
~
'e erfor ta ti.c un 4 t of "ur! cc,
of arm m mn '
.s t M r.
sup i t.
i; f'
f ic! !
i Jel
'n I t' 1
c 31 l'ir i;,t 1
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muct be treated simultaneou.vly because of our inabi'ity to forecast the cource area of radiated peaks of sciamic< energy, the possible g
dnteraction noong the faults ncar and under the site, and the virtual absence of stront; notion records in cuch proximity to potential source areas for large earthquakes. 11anks (1974), for example, considered, based on the st rong motion record written by 'the 1971 San Fernando ea rt hquake at Pacoima Dam, that the breahout. Phase indicative of near-surface rupturing occurred during the time interval of the strongest ground tac t ion.
The licensec argues (Unrth Sciences Associateo, 1978d) that strong ground tiot ion will t ravel at shear-wave velocity and that rupture will propagate at about 70 percent of shear-vave velocity, Eccause of this velocity dif f erential there unuld be a de]ay. time at. the cite of several seconds between the arrival of the strong motion and the propagat.ing rupture.
While thesc' ascumpt ionn are not unreasonable, there exist nany uncertainitien such no ihose descrJbed above not enconpassed by thin line of re,soning.
It in our conclecion that aufficient justification doec not exist for separating in tine the effects of strong ground taat ion and o f f s et : of urface rupturin;,.
1
p
~
,,4 Anderson, D. L.,1971, The San Andreau Fault, Scientific American, V. 255, No. 5, pp. 53-66.
Bartowa, A.
G.,
Kahle, J.
E., Weber, F.
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Jr., and Saul, R.
B.,
1973, Map of Surf ace Dreaks Resulting from the San Fernando California, Earthquake of February 9, 1971; in San Fernando, California Earthquake of February 9,1971, U. S. Department of Commerce, Washington, D. C.
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' Earthquake Swarm of January 8,1977, Contra Costa County, California
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Buchanan, J.
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- p. 55-76.
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Carpenter, D.
U., 1977, Ctologic Investigations for Master Plan j
rormlation, Santa ni La Property, Prepared for Alameda County l
Ponrd Supervisora, 17 p.
l Coffman, J.
L., and Von Fake, C. A.,1973, Eart.hquake History of the U.
S., U. S. i)ept. of Commerce (NOAA), Pubid ention 41-1, 208 p.
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Farth Scien i Associates, 1978a, Geologic Investigation General Electric Tent Rnac tor Valla i h m, Califorula (Preliuinary); Prepared for Genera]
Electric Co., PJ om,anton, Call f orni a.
Earth Sciono Acoci a te u, 197%, Crotonic Tr < st igat J oa Genernt Elect ric Test b ct or V 13 eci t on, CalJ fo:nia; Propa ed for General Electric am, M iiornic Co., Plo i
i;.n
.g.!
u C..m rl?
M s
i
'[ lith C 'i e; I ;it e i, 1972', O. ili Tent b n e t o r \\'. t 3 l o c i t o :, Caliicruin, h o d t n i t
3; f et paa d 1or C.: n...1 zitra, Cali!ornia.
E3 cc t r l:.
Co,,
Pl<
2
~
Earth Sciencea Associates, 1978d, Coologic Evaluations of GETR Structural Design Criteria, Prepared for Cencral Electric Co.,
Pleasanton, Calif ornia.
Earth Sciences Associates, 197Cc, Landslide Stability Cencral Electric Test Reactor Site, Valleciton, California, Prepared for General Electric Co., Plennanton, California.
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Engineering Decision Analysio company, Inc., 1977, Scinnic Criteria and Baois for Structural Aunlysin of Reactor Building, Attachment 1; j
Prepa red for General Electric Co., Pl ea santon, Cclif ornia.
l Engineering Deciclon Analysis Company, Inc.,1978, Determination l
of Vibratory Load:, to be Combined with Fault Displacements Loads; Prepared for General Electric Co., Pleacanton, California.
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11all, C. A., Jr.,1958, Geology and Paleontology of the Pleasanton Area, Alaneda and Control Costa Countien, Californj a, Calif. Univ.
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34, No. 1, 63 p.
llanks, T, C.,1974, The Faul ting Mechanim of the San Pernando Earthqucke Journal Geophysical Reccarch, Vol. 79, Mo. 8, pp 1215 1229.
lhinks, T.
C., and D. Johnuon, ]976, Ceophysical As >nnment of Penh Acce]etatfonn Full. Scian. Soc. Ater., Vol 66, p. 959.
11 erd, D. G.,.1977, Geologie Map of the Lao Ponitau, Greenville and Verona Paults,1 :tntern AL uda County, Cali f ornia, USGS Open-File Ecpott 77-689, 25 p.
Judd Hull and Annociaten, 1977, Geolor,Je Inecatigation for Proposed Civi c Cent er Addi rions, P i em ant on, Callfornia, Propered for City of Pl ea: nnton, CalJfornia, 24 p.
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Eaton, and E E. Urabb, 1971, The Earthquahe Sequence Ucar lhavJlle, Calif o rni a, 1970, Uull. Seica. Soc. An. V.
61, p. 1771-17%.
Pagu, R.
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and Coulter, H.
U., 1972, Ground Motion Valuer, for U:e in the,k i mi c Dal en o f the T1.ms-Ala hn ip lim
. ten, U.
C..J. J eal u:.m Circular 672, pp 23.
3 t.,a Prince, U.
S., 1957, Earthquake Considerations at Propoacd GETH Site, Cencral Elect ric Company, Atomic Pcuer Equipment Depart:nent Report, CEAP lio. 1050.
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R., and Grantz, Arthur, eds., Proceedings of conference on geologic problems of San Andreau. fault systen:
Stanford Univ. Puba. Geol. Soc., V. 11, p. 46-54.
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