ML20213A397

From kanterella
Revision as of 06:23, 20 January 2021 by StriderTol (talk | contribs) (StriderTol Bot insert)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search
Summarizes ACRS Subcommittee on Extreme External Phenomena 861120 Meeting Re Facility long-term Seismic Program.Studies Necessary & Conducted in Excellent Manner
ML20213A397
Person / Time
Site: Diablo Canyon  Pacific Gas & Electric icon.png
Issue date: 11/30/1986
From: Thompson G
AFFILIATION NOT ASSIGNED, Advisory Committee on Reactor Safeguards
To:
Advisory Committee on Reactor Safeguards
References
ACRS-CT-1873, NUDOCS 8702030256
Download: ML20213A397 (1)


Text

_ . . . _ _ . _ _

0-M7'9 George A. Thompson 421 Adobe Place Palo Alto, Califomia 94306 November 30, 1986 To: ACRS Subcommittee on Extreme External Phenomena, via Richard Savio From: George A Thompson -

Subject:

Report on November 20, 1986 Subcommittee meeting on the Diablo Canyon Long Term Seismic' Program This report attempts to highlight a few important topics re-lated to the meeting. In general, the program is energetically engaged in fact-finding and, as yet, is less focussed on alter-native tectonic models. Increasing emphasis on models/ hypotheses and the priorities for testing them will be useful from here on out, because the general scientific problems are open-ended.

The Hosgri Fault Zone is deservedly receiving greatest emphasis.

By Hosgri Zone I refer to the broad band of active and inactive fault strands that may have both strike-slip and reverse movement.

The fault zone extends northward into the San Simeon fault and poss-ibly also includes strands seaward of San Simeon Point. Alternative working hypotheses about the fault zone need to be defined as clearly as possible: (1) It isataSan complex, the present evidence Simeonprimarily strike-slip)(2zone, clearly suggests? asare If so, splays from the the thrust faults,faults, strike-slip seen inasseismic is the case re'flection at somesections,long places a the San Andreas Fault? (3) Are the thrust faults independent late structures that cut or join the strike-slip faults? An intensification of com-pression and thrusting in the last 3-5 million years is in accord with a change in Pacific plate motion evidenced by hotspot tracks and by the geology of the Coast Ranges. (4) Do the thrust faults have a significant earthquake potential in crystalline bedrock beneath the plant?

The emerging analysis of earthquake records is' making a lot of sense and should help to narrow the possibilities for future earth-quakes.

A second focus of concern is the San Miguelito and other on-land f aults that are more or less on trend with it. This problem is being addressed effectively by a variety of studies, but getting definitive answers may be difficult or impossible. I would like to see an analysis of the possible hazard based upon alternative assumptions within the bounds of obtainable evidence.

about, these faults,believe I continue to that the studies are necessary and rele-vant. They are being managed and conducted in an excellent manner.

Sincerely, 8702030256 861130 '

PDR ACRS CT-1873 PDR

.y

_