ML20236L922
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pa ge 1.
Supplemental statement by Flalph Vrama concerning J
testimony of the August 7, 1970 hearing tefore the AEC Board in 3cn Luis_ 0 bispo, California i
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The comments in this report ura on points raised l
1 in the au6ust 7,1970 hearing.
I have not seen the f
report to be submitted by the A30 consultas.ts and the applicant on points raised at the au6ust 7th hearing.
f i
I understand that I will have an udditional fif teen I
days beyond the thirty granted for filin6 this report, in which to comment on the reports of the other parties.
These are my findings, titled as follows:
1.
The offshors epicenters 2.
The need for u geologio map of the Port Uun i
Luis t,uudrangle.
3.
The 4dnu fault 4.
Somo general comments (continued on page 2) 4 8708100408 870729 PDR FDIA CONNOR87-214 PDR w
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1.
The off-shore Ipioenters The offshore earthquake series of 1969-70 was discounted by the AEC's consultants und by Dr. Johne.
Their testimony i
appears on p. 52, 53, 90, 91, 97, 98, 104, 111.
On these ja ges their main contention was that fracture zones do not brameh as I maintained.
Ok pa6e 90, lino 12-16, Dr. Jahms states: "So we are really talking about branches here of five or ten degreest right?
Iam't this one of tho churnoteristics of all the so-called fracture zones on the sea floor, where they branch the ang$es are very small?
( empha si s mine ).
Dr. Jahns continued on p. 91, line 9-lE, that my description i
of these epioe:itera as a branch of the ll.uITa;' fracture zone was unique in terms of any features we know about these continental scale structurse.
(emphasis mine ).
Further study indioutes to me that three fracturo zones off South Ameriou show bruxching in. precicely t e direction I suggest for the Lurray (angles of 45 dodreec).
The word " branching" is
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used to describe this in H. a. Renard's work.
"Three fracture zones branch" he caya on p. 43 of " Marine Geology of the puoirio",
a book referred to in the hearings.
(cap. p. 42, Monard)
Again, en p. 97 of the t estimony, Dr. Ja;th finds it "very difficult to reconcile that geonetry (branching of the Murray Fracture Zone) with any conceivable interpretation of global l
tectonios".
Furthor study convinces me that there are established l
branches of the Eurray Fructure Zone parallel to the line of epicenters.
The goometry Dr. Smith finds very difficult to
Pr 3 reconcile with 6 obal tectonica is established even in the 1
fracture zone under consideration.
It is just possible that this 8sometry is crucial in an understanding of the structure of the westerm margin of the North American contiment.
(See the map in the 3assingor report, " Interpretation of Mugnetio Amoralies off Central California").
This map shows faults l
bramohing off the Murray (designated as "c" and "D" on the l
map).
Om page 104 of the testimony Dr. Jahms again refers to the remarkably strajght churuoter of the oceanic faults.
I agree with him that they are soe But Dr. Jahms maintains that to i
send off banches at 45 degrees "very soon proposes a mechwa ical l
problem that is virtually insoluble, when cae is dealing with the scale of those things".
Further study indicates to me that not only is the problem solved but en axolaxation of why i
branchet;4xist is given in U2 nard's book (se<.
pages 136 and 137).
It is quite likely that the same explanation that Monard pro, poses for the branching of nomos off the South american coast applion to the Murray.
Ho postulates that a bend in the continental coast is a necessary starting point.
There is just such a ' send in tho California coast whero the ll.urray fracture approathos shore.
On pago 52, Mr. Waldron indicates that to has no evil enos to warrant any association of these epicoaters with the Eurray fracture.
Further study indiontes to me that there is such
- p. 4 l
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evide nc e.
A seismio study morth of Arguello canyon in the l
l re6 ion of the epiobaters was made by Von Hueno of the United Statos Geological Survey.
It was entitled, "Geolo61o Structures i
l between the Murray Fracturo Zomo and the Transvarso Ranges" and 3
appeared im Marine Geology v.7, 1969, p. 475-499.
He found that l
the sediments morth of Arguello Canyon showed tootomism.
(Tectomism j
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is defined as crustal instability in the Dictionary of GeoJ ogical l
Terms).
This is in the ro6 ion of tbs epic antors.
Some of the linear elomonts of the Rodriguez bench (just south of the epicenters) 1 l
trend in a northeast dirootion.
Von Huomo supports tbc idea j
that the lower course of the Arguello Canyon is " structurally oojholled". (emphasis mine).
The Arguello Cunyou trends northeast l
in the region of the epicenters.
Vone Huone also supportre the idea that the Rodriguez seamount and Davis seekno*.1 " formed along l
one or more northeast-trending conjugate fissures of the Eurray".
i (emphaals mine).
I kr. daldron socc no relation between the Eurray Practure zone and the off shoro opicenters.
The bove evidence, of a positive nature, affirms the possibility of a connection.
I do not claim more at this time, Tho " state of the art" in geology is advanced enou6h to supply the information necessary, if only it is applied.
i Er. "saldron and Dr.
Jahns utnted to know how to determine wh other there is a connoo tion between the Murray fracture and these offdiore l
opioenters.
I suggest the following (obtiimed mainly from like studies done elserhere):
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A hydroacoustic study which will detect minor earthquakoo l
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1 in the region of the epioenters.
Such a study was made for the eastern end of the Meadooine Fracture Zone and was reported by-Northrup, Menard and Dusmaebier in " Science", Aug.16,19tB.
In this connection Chairman Gleason on p. 96 emphasized the
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l importasce of a question asked of me by Dr. Smith comoerming 1
i small earthquakes as defining structure.
Northrup's report
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used very small earthquakes in his study to investigate a mascent fracture zone branching 'off from-the Eendocino.. Thus i
l it is possible to defino structure using small shocks at least j
in the Eendocino area.
It seems worthwhile to ocasider trying it in the 1*urray Fracture Zone.
2.
IIent flow measurements in the region of.the epicenters.
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This will indicate if there is similarity to the branching of
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the South and Central American fracture zones where volonaism j
I has accompanied the branching.
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3.
Installation of a more accurate seismograph monitoring l
system.
This can be done by placing seismographs in the San Luis Obispo vicinity.
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A magnetic anomaly study of the region near the epicenters.
I This may indicate faulting below the sediments.
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A gravity anomaly survey of the region.
Some of this has been dono and was in part the basis for Von Huene's belief that the Transvers ranges do no_t connect structurally with the Murray fault.
The gravity anomaly map of San Luis Obispo Collaty will be out la early 1971, I have been advised by the California Div$ sion of Eines and Geology.
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- p. 6 l
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An acoustic reflootion profiling of the area of the opioentero.
Tllis will delineate tectoniam in the codiments,
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if thero is any.
7.
A detailed bathymetric curvey between the region of the l
l epicenters and the calst contiguous to the plant.
1 2.
The Need for a Geologio Rap of the l' ort Sun Luis undran6 e q
s There is need for a careful atudy of the area within a rudius of about 10 miles of the plant.
Juch an area would cover #1e Port l
Gan Luis quadrangle.
Clarance Hell's planned mapping of the Port 1
Jan Luis quadran6 o would fulfill this careful study.
Such a map j
1 is a necessary document to protoot all parties from criticism that tbsy were not thorough enough in their studios.
"A Good 68010g10 cap ", wri ta s Dr..Tuhne, "is neccesary but not sufficient for purposer of dafining hazards and various levela of rist...."(see al so p.120 of the tastinny).
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3.
The 2dna Fault I asked that the 4dna fault zono be conaldered by thoso involved with ussesning onrthquuto danger at the propocod inctsllation.
Several questions still remain in my mind.
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The connection between the Ednu faul t and the Los Osos fault nas disputed by Dr.
Jahn3 at the Au6 7,
1970 hearing.
He said 1
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that the 2dna fault had its lower side uway from the San Luis Valley and homeo was not related to the formation of that valloy.
There are branches to the Edna fanit, sometimes three, and these branches
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H show movement different than Dr. Jahns indicated.
Cae branch moves as he said, the others do not.
The following quote from Clarance Hall from his field trip notes in the area may help.
"During the last few yeare an our mappin6.has progressed we at first thought that the ciost Hunana fault continued to the northwest near Edna toward Seo Canyon and westward to the ocean.
However, our recent mapping has shown that the series of parallel faults that are immediately south ofEdna and in the See Canyor. area are dip-clip faults, each witha a displacement of a few hundred feet, and that tha main Yleet Huasna fault may continuo e.ither northwest throtch Los Osos Valley, or toward ana Luis Obispo or Ctosta grade."
(1900 field trip to the Hipomo-Arroyo G1cnde arca, arrangc6 for the GSA meetin6 und which IIall's may of the Arroyo Grando should now be in the hands of i
the Board).
O Soma *. ei3ral Comr. ents It m s n.y u-dcrateMing that we would all exchange copies of our my e.
I r::!4e mine available to tho other partie c concerned viu !Lr. Crase of the P.G. emd E.
It was my impression that everf' one vished to move as quickly on thie as possible.
I asked Er. Dsvine ir the testimony for his map on which he based a northwest-southeast alignnant of the controversial epicenters.
I Peminded him af ter the hearing that I would like it and Mr. Crano reminded him.
I have not yet received it.
I wrote Dr. Jahms also for a copy of the 10 square mile map of Diablo Canyon which he did not include in the PSAR, I have had no reply from
- p. 8 Dr. Jchns.
For my own researebos ur well as for c.:ty bearing is n.ight have on the once, I receivad permission to enter land naar the proposed.31 ant to investi$ ate what looked l'.ko a fault on aerial photos about a mile and a hair from the planf site and im a XW-SE direction.
Thie investigation contixues.
l Respectfully, W$
.W%
l Ralph S. Vrana, Intructor Physics Depa rtsont, California State Po.lytechnic Colle ge, Sun Luis Obispo, Chlifor2.ia Dated:
September 5 1970 l
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