ML20209C048
| ML20209C048 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Diablo Canyon |
| Issue date: | 03/18/1983 |
| From: | Rolonda Jackson Office of Nuclear Reactor Regulation |
| To: | Knight J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20150F500 | List:
|
| References | |
| FOIA-86-391 NUDOCS 8303230524 | |
| Download: ML20209C048 (5) | |
Text
MAR 181983 DISTRIBUTION:
DOCUMENT CONTROL DESK GSB RDG
!!EMORMIDUtt FOR:
James P. Knight, Assistant Director for
[-
Components & Structures Engineering, DE FPOM:
Robert E. Jackson, Chief Geosciences Branch, DE
SUBJECT:
DIABLO CANYON - Hnsr@I FAULT DISCOVERY CHPON01.0GY As you reouested, please find attached a limited chronology of events relating to the Hosgri fault as recalled and reassembled by R. McMullen of the Geosciences Branch. This should be considered as a draft for the time being.
If it becomes necessary, we can recheck the authenticity nf the infomation and polish the presentation. This chronology certainly reveals the extensive arrount of work that has taken place over the years. This was previous 1v issued on March 14,19R3 but item n nnber 18 was improperly described in that memo.
0T1 tnal Signed by 8
E*.H._ Jackson Pobert E. Jackson, Chief Geosciences Brarch Division of Engineerirg
Attachment:
As stated cc: w/sttachment S. Broccum I.. Reitar R. McMullen R. Rothman t.. Chandler B. Buckley G. Kniahton H. Schierling 1 Devine, USGS Y
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DIABLO. CANYON - HOSGRI FAULT
SUMMARY
STATEMENT: The AEC first learned of the fault, later to be called the Hosgri fault, in 1973 during its review of the FSAR, from a description of the fault given in that document. Questions generated by the AEC staff and its advisor, the U. S. Geological Survey, regarding this fault and its significance to the seismic design of Diablo Canyon caused extensive additional investigations by PG&E over the next few years. Concern about offshore structure in general also resulted in numerous independent offshore investigations by'the USGS, many of them funded by the'AEC-NRC. Synthesis and interpretation of the data from all of these studies led to the September,1979 Partial Initial Decision of the ASLB and the June, 1981 Decision of-the ASLAB. The following is a general chronology of significant milestones in the geologic and seismologic evaluation of the Hosgri fault zone.
1.
1966-1969. Detailed onshore geological investigations and seismologic evaluations were performed by PG&E during construction permit phase. Offshore investigations did not seem to be necessary to PG&E (Bettinger Testimony, 1978) because:
- a. low seismicity and the absence of seismic activity that would indicate a nearby offshore fault;
'. b. the assumption a magnitude 6.75 earthquake near the site which was expected to envelope the maximum earthquake on any offshore fault;
- c. geologically mapped sea cliffs north, west and southwest of the site (any offshore major. structure would be indicated on cliffs) and;
- d. they had trenched and geologically mapped at site and the trenches were oriented according to regional geologic structural grain.
2.
1970. USGS report
" Preliminary Reconnaissance Marine Geology of Area Between Santa Lucia Escarpment and Point Buchon, California,"
by S. L. Wolf and H. E. Wagner. Reflects USGS concern about offshore structure that may have been related to an apparent NE-SW alignment of earthquakes that occurred during late 1960's and early 1970's between the Santa Lucia Escarpment and Point Buchon. The apparent NE-SW earthquake alignment is approximately perpendicular-to the Hosgri fault zone. (June 28, 1982 letter from D. G.
Frederick, USGS to F. Eissler, Scenic Shoreline Preservation Conference,Inc.)
3.
1971. Hoskins, E.G. and J.R. Griffith publication
" Hydrocarbon potential of Northern and Central California offshore," in Cram, I.H. (editor), " Future Petroletm Provinces of the U. S. - Their Geology and Potential"; AAPG Memoir 15, Vol. 1, pp. 212-218. Based WA 8% ~3W ff-/.1L4
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on' data (proprietary) gathered in mid 1960's they described a sedimentary basin offshore from Diablo Canyon, bounded on the east side by a fault (later called Hosgri).
4.
1972.
PG&E, through its consultant, Earth Sciences Associates (ESA), learned about the fault while preparing the FSAR.
D.
Hamilton, ESA, interviewed Hoskins and examined some of the proprietary data (Bettinger, 1978).
Included description of the fault in the FSAR. PG&E concluded that the assumed maximum local earthquake of magnitude 6.75 was adequate.to envelope the earthquake from.this fault.
5.
1973.
FSAR submitted to AEC staff with application for OL. AEC learned about the Hosgri fault from the FSAR.
In a later amendment it was referred to as the Eastern Boundary fault.
6.
1972 & 1973. As part of the ongoing California research program offshore investigations were being carried out by the USGS with AEC funding.
Interpretation of the data from these studies required months and years to interpret, and the information was not published until much later.
Interpretation of these data confirmed the existence of the Hosgri fault zone and defined its extent and recency of movement.
- a. USGS Bartlett Cruise in 1972 - Silver, E. and R. von Huene, 1975, " Seismic reflection profiles, USNS Partlett, Nov.1972 cruise offshore central and southern California (Legs 2 and 3), USGS Open-File Report 75-121.
- b. USGS Palaris cruise in 1972 - Wolf, S.C.,1975, " Seismic reflection profiles R/V Polaris, March, 1972 offshore southern California, Point Conception cruise," USGS Open-file Report 75-166.
- c. USGS Kelez cruise in 1973 - Wagner, H.C.1974, " Marine geology between Cape San Martin and Point Sal, south-central California, offshore, a preliminary report, August,1974;" USGS Open-File Report 74-252. The fault is named the Hosgri fault.
7.
1974 USGS requests additional information about the fault in letter from E. H. Baltz, USGS to W. P. Gammill, AEC, March 28, 1974.
8.
1973 & 1974.
PG&E initiated investigations offshore of its own, partly in response to questions from the staff and USGS. These data were provided to the NRC and USGS reviewers.
- a. December, 1973 - White Plume Survey by Bolt, Beranek, and Newman (BBN) of Houston.
- b. July, 1974 - State Race survey by Aquatronics, Inc.
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9.
1975.
In February 1975 and November,1975 questions by the USGS and NRC were sent to the applicant requesting additional information on the Hosgri fault, its relationship to regional tectonics and other faults in the region, its earthquake-generating capability, and ground motion effects. By this time USGS data previously obtained was available, the interpretation of the data from the applicant's investigations had been completed, additional proprietary data from oil companies was available (Western Geophysical Co., 1974). The answers to the NRC and USGS questions were provided in amendments to the FSAR from 1974 through 1976 and are included in Appendices 2.50, 2.5E and~2.5F.
i 10.
1976. USGS final report transmitted by a April 29, 1976 letter from Henry W. Coulter, USGS, to Benard C. Rusche, NRC.
In that report the USGS concluded as it had in an earlier report (January, 1975), that a magnitude 7.5 ehrthquake could occur anywhere on the Hosgri fault and that that earthquake should be considered.
Horizontal ground motion should be as described in USGS Circular 672 (NRC SER Supplement 4,1976).
11.
1976. The HRC adopted the USGS position, and based on advice of its consultant, Dr. Nathan Newmark, required that an " effective" horizontal ground acceleration of 0.75g be used for the development of a design response spectra (NRC SER Supplement 4,1976).
12.: 1978. NRC staff summarized its position on the Hosgri fault zone in written testimony in preparation for the ASLB Hearing beginning December 4,1978. USGS submitted their April 29, 1976 report as testimony.
13.
1978.
PG8E summarized its position in the December 4,1978 written testimony.
.14,
1978. May and June, Fugro. Inc., under contract to USGS conducted an offshore geophysical survey between Point Sal and Point Conception and published data in a November 15, 1978 report, Investigation of the Hosgri fault offshore southern California, Point Sal to Point Conception."
15-December 1978 - February 1979 - Seismic ASLB Hearing for Diablo l
Canyon.
- 16. September 28, 1979 - ASLB Partial Initial Decision on seismic matters.
17.
February 28, 1980 R. B. Leslie Affadavit about Hosgri-San Simeon faults, based on interpretation of 1979 Seismic reflection profiles between Cape San Martin and Point Estero run under USGS contract.
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1980 - ASLAB Hearing on Imperial Valley Earthquake data applied to Diablo Canyon and new evidence from the.USGS that 1927 Magnitude 7.3 Lompoc Earthquake occurred either on the Transverse Range Structure or the Hosgri.
- 19. June 1981 - ASLAB Decision
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