ML19256F674
| ML19256F674 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 12/07/1979 |
| From: | Devine J INTERIOR, DEPT. OF, GEOLOGICAL SURVEY |
| To: | Rolonda Jackson Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-06, TASK-3-6, TASK-RR NUDOCS 7912190791 | |
| Download: ML19256F674 (4) | |
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United States Department of the Interior
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GEOLOGICAL SURVEY 7
RESTON, VA. 22092 In Reply Refer To:
December 7, 1979 Mail Step 905 Dr. Robert Jackson Chief, Geosciences Branch Division of Site Safety and Environmental Analysis U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Bob:
Enclosed are the USGS questions concerning the study entitled " Report of the Evaluation of Maximum Earthquake and Site Ground Motion Parameters Associated with the Offsnore Zone of Deformation San Onofre Nuc Generating Station" by Woodward-Clyde Consultants.
If you wish to discuss these further please let me know.
Sincerely yours,
- (ha-hamesF.Devine Deputy for Engineering Office of Earthquake Studies 1627 557 S.. '.
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%e Hundred Years of Earth Science in the Public Service 9 ', f,_ Q, g 7912190 e6
December 7, 1979 USGS questions concerning San Onofre Nuclear Generating Station 1.
Based on the literature, some strike-slip faults fall well outside the " Design Earthouake Limit" line shewn on figure 7 of the 1979 Woodward-Clyde report entitled " Report of the Evaluation of Maximum Earthquake and Site Ground Motion Parameters Associated with the Offshore Zone of Deformation San Onofre "uclear Generating Station."
Matsuda (1977, table 1) gives slip rates for several strike-slip faults that have had large historic earthquakes, as follows:
Earthquake Magnitude Slip Rate, mm/yr 1891 Nobi 7.9 (probably from intensity) 1-5 1927 Tango 7.5 0.05-0.1 1943 Tottori 7.4 0.05-0.1 1974 Izu-Hanto 6.9 0.5-1.0 The slip rate of 20 mm/yr used by Woodward-Clyde for the North Anatolian fault has been modified in some recent literature.
The 20 mm/yr rate is based on Pavoni's interpretation of 300 400 km displacement on the Anatolian fault, but this interpretation is strongly disputed by Ketin (1969) who conculdes that the displacement is much less.
A later report (Canitez,1977) says the slip rate in the last 15 m.y. has been 5-6 mm/yr and in the last 1/2 m.y. has been "about 7 mm/yr" (abstract) or
" greater than 7 mm/yr" (text).
The 1976 Tan Shan earthquake of magnitude 7.8 was a complex event that was predominatly strike-slip with about 1.5 meters of displacement. The Chinese were aware of the fault in the coal mines, but did not consider it active.
Inasmuch as Chinese civilization has been centered near Tan Shan for several thousand years, the geolog'c slip ratae on the fault is very probably less than 1 mm/ year.
Kanamori (1973) states that the 1948 Fukui m 7.3 earthquake, predominatly strike-slip, occurred on fault with a slip reate less than 0.3 mm/ year.
Please assess the impact of these comments on the slip-rate technique for estimating earthquake magnitudes.
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References Canitez, Nezihi, 1977, Dynamics of the North Anatolian Fault, in Proceedings of the CENTO seminar on recent advances in earthquake hazard minimization:
Iran Tech. Research and Standards Bureau, Plan and Budget Crganization, Publication 70, p. 353-366.
- Kanamori, H., Mode of strain release associated with major earthquakes in Japan, Annual Review of Earth and Planetary Sciences, vol. 2, Donath et al. eds., 1973.
Ketin, Ihsan,1969, Uber die nordanatolische horizontal-vershiebung:
Mineral Res. and Exploration Inst. of Turkey, Bull.
(Foreign Ed.), no.
72, p. 1-28.
Matsuda, Tokihiko,1977, Estimation of future destructive earthquakes from active faults on land in Japan: Journal of Physics of the Earth,
- v. 25, suppl., p. S251-S260.
2.
In Woodward-Clyde's empirical search for a correlation between geologic slip rate and maximum magnitude there is a serious sampling bias in restriction of magnitude data to historic earthouakes, even though there may be no alternative. A fault with a smaller geologic slip rate will have a smaller rate of seismic activity, on the average. Therefore, the largest earthquake experienced in historic time is less likely to be near the " maximum magnitude" for a fault with a small slip rate.
Please explain how this concept impacts the confidence in the placement of the " Design Earthquake Limit" line on figure 7.
3.
Survey reviewers believe there is a problem with the functional formac(R+C)#usedintheregressionandwiththevglueadoptedfor C.
There is no physical basis for the form <x(R + C).
Furthermore, C =
20 has not been demonstrated to give a better fit than other values.
Furthermore, it needs to be demonstrated no; only that C = 20 gives ;
better fit but also that the better fit is statistically significant.
Moreover, site-specific data set should be used to determine C.
If C means anything at all, it should be considered a site-dependent t
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4 property, since a likely mechanism for limiting acceleration is the finite strength of the near-surface materials at the recording site.
Consequently please explain the validity of the quantity C = 20.
5 4.
Strong motion data recorded at the base of large buildings have been included in the ground motion ?nalysis. 'Aork by Boore and others (1978) and Crouse (1978) suggests that the peak acceleration values recorded at such sites may be biased downward from the values that would have been recorded under free-field conditions. A number of records have been included from NW California earthquakes, the locations of which are I
subject to notoriously large uncertainties.
The weighting scheme gives these data equal weight with the San Fernando data for which the distances are much more accurately known. Also, a large number of strong motion data points have been attained very near to the fault during the two recent California earthquakes (Coyote Lake August 6, i
1979, and Imperial Valley October 15, 1979).
Please assess the impact of these comments and of the new data on your estimates of peak ground motion at the SONGS site.
l References Boore, D. M., Joyner, W. B., Oliver, A. A. III, and Page, R. A.,1978, l
Estimation of ground motion parameters:
U.S. Geological Survey Circular 795, 43 p.
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Crouse, C. B.,1978, Prediction of free-field earthquake ground motions: Proceeding, ASCE Specialty Conference Earthquake Engineering and Soil Dynamics, v. 1, p. 359-379.
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