ML20234D956

Forwards Comments on Seismolgical Aspects of St Amand Rept Geological & Seismologic Study of Bodega Head

ML20234D956
Person / Time
Site:	05000000, Bodega Bay
Issue date:	10/11/1963
From:	Neumann F NEUMANN, F.
To:	Hadlock G US ATOMIC ENERGY COMMISSION (AEC)
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ML20234A767	List: IA-85-665, Discusses Seismic Design of Nuclear Power Plants,Including Const of Nuclear Plants in Seismically Active Zones ML20234A761 ML20234A769 ML20234A792 ML20234A798 ML20234A803 ML20234A812 ML20234A816 ML20234A827 ML20234A830 ML20234A838 ML20234A841 ML20234A844 ML20234A847 ML20234A851 ML20234A855 ML20234A858 ML20234A861 ML20234A864 ML20234A868 ML20234A871 ML20234A874 ML20234A893 ML20234A896 ML20234A900 ML20234A911 ML20234A922 ML20234A929 ML20234A932 ML20234A937 ML20234A944 ML20234A956 ML20234A965 ML20234A968 ML20234A976 ML20234A984 ML20234A993 ML20234A996 ML20234A999 ML20234B005 ML20234B008 ML20234B023 ML20234B032 ML20234B035 ML20234B040 ML20234B062 ML20234B066 ML20234B076 ML20234B084 ML20234B098 ... further results
References
FOIA-85-665 NUDOCS 8709220243
Download: ML20234D956 (4)

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, THANK NEUMA'NN 4 54 s rentv-rerTH AVCMut N.E.

SEATTLE. WABM 981D5 J

. October 11,-1963.-

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'I Mr. Gerald P. Hadlock, Counsel for AEC Regulatory Staff, U. S. Atomic Energy Commission, Washington 25, D. C..

I - Res Pacific Gas and Electric Co.,

Bodega Bay Atomic Park, l Unit No. 1, 1 Docket No. 50-205 j

Dear Mr. Hadlock:

On September 12 you mailed me a copy of. Dr. a Pierre Saint-Amand's report entitled " Geologic and Seismologic l Study of Bodega Head" with the request that I comment on it, i if possible at the September 17 meeting in Bethesda. As the report did not reach me in Seattle until after I returned from the meeting I made only a few verbal comments to you after looking over a copy of the report in Bethesda.

I I am enclosing some, written comments on the report in  ;

order to keep your records complete.- I am also reporting to-  ;

day to Dr. Bryan on Jerry P. Eatord report a copy of which Dr. i Bryan sent me earlier in the week.

I Very truly yo rs,  !

s-UNM( bhe -_ -- ,v Frank Neumann.

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Comments on " Geologic and Seismologic Study of Bodega Head" by St.

Amand, 1963.

By Frank Neumann '

(Only the seismological aspects are discussed in the following paragraphs.)

At bottom of p. 5, St. Amand states, "A combination of the fracturing, mylonitization, deep weathering, and an abundance of ground water render the bedrock far less stable than similar rock would be had it not been comminuted by the cons of shearing which it has undergone." If this condition extends down to depth of the order of 50 feet, then the granodiorite in Bodega Head may not possess all the seismic stability we generally credit to granitic rock--a rock which for the present purpose must be defined as one yielding minimum earthquake intensities. The writer has previously stated in AEC memo-randa that the true seismic foundation factor at the Head can be obtained only l l

af ter a number of strong motion seismograph records are obtained on this rock. I For epicenters within only a few miles of the Head the local geology is not a serious factor, but if the rock were less stable than granite, a maximum intensity might be experienced from earthquakes that centered poscibly 10,20, or 30 miles away. The rapid intensity attenuation found in granitic basement l rock would not apply to the allegedly less stable rocks of Bodegi Head.

Page 16, Richter's tabic showing magnitude-intensity relationship. St.  !

Amand says the table values are in good agreement with those observed in actual 4 earthquakes. Just how good this agreement is can be seen in Fig. 4 of the writer's paper on Bodego Head now under review by the L & R Division of A.E.C.

The table entirely ignores the' lower intensities experienced on granitic rocks l 1

for the deeper type California earthquakes, and the reader is lef t to conjec-ture what it might be. Fig. 4 shows it directly. 'Ihe writer deplores the  !

practice of those who attempt to evaluate the work of others without offering

. any worthwhile evidence to support such evaluations.

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, f I 2-In the middle paragraph of p. 16 St. Amand explains the attenuation of the El Centro carthquake as being due to the thick alluvium beneath El Centro.

Fig. 3 of my report, which is now being reviewed, shows El Centro as having the minimum intensity of a town on the thick sedimentary basement of southern California, so there is no need to postulate a thick alluvial overburden to explain its intensity or the character of the record obtained. We are not sure to what extent the sedimentary basement itself " alters the power spec-trum." St. Amand assumes this alluvial cover somewhat masked the'effect of the " fling" at El Centro. In my recent comments on statements by Prof. Housner in Chicago I stated that the acceleration due to this so-called " fling" is quite cicarly defined on the El Centro acceleration record. St. Amand evidently hoped to see his " fling" concept better illustrated on seismograph records than it actually is. As to the shaking being much harder in the direction in which' faulting progresses, this is entirely a theoretical consideration that still l

l has to be proved from observational data. The shaking is certainly not so '

L much harder that it can be immediately spotted on an intensity distribution l

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l map of a shaken area. None of these are seriously important considerations l but point up the weakness that many seismologists have in treating their theoretical concepts as facts.

In paragraph 4 I thoroughly agree with St. Amand in his statement that the historical record shows very clearly that higher intensities go with larger earthquakes; and that the use of the El Centro record will not guarantee ade-quate design factor for che proposed Bodega Head power plant.

Using the equation at the bottom of p.16 St. Amand arrives at a value of 1 g for mm-10 1/2. If referenco is made to Fig. 5 of the writer's Bodego Head report now in preparation, it will be seen that the same result will be J. (

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5 formula quoted by St. Amand.

. Last line on p.16. - St.' Amand evidently believes that 1 g. accelera-tions have been observed; so does the writer. Dr. Housner does not..

Seattle, Washington, t October 11, 1963 .

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