ML20213E788
| ML20213E788 | |
| Person / Time | |
|---|---|
| Issue date: | 04/25/1984 |
| From: | Rolonda Jackson Office of Nuclear Reactor Regulation |
| To: | Vollmer R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20213E750 | List: |
| References | |
| FOIA-86-197 NUDOCS 8405150176 | |
| Download: ML20213E788 (2) | |
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'% , , , , , # April 25, 1984 MEMORANDUM FOR: Richard H. Vollmer, Director Division of Engineering THRU:
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l James P. Knight, Assistant Director for Components & Structures Engineering Division of Engineering FROM: Robert E. Jackson, Chief Geosciences Branch Division of Engineering .
SUBJECT:
MAGNITUDE 5.8 EARTHQUAKE NEAR SAN JOSE, CALIFORNIA ,
An earthquake occurred on April 24, 1984 10 miles southeast of San-Jose, California near the town of Morgan Hill. The following preliminary information was provided by the USGS, the National Earthquake Information Service, the California Division of Mines and Geology, NRC Region V and the Incident Response Center.
The magnitude 5.8 (mb) earthquake occurred at 21:15:17.2GMT (1:16PST).
The epicenter was located at 37.3N, 121.8W and the focal depth was about 10 km. The event has been associated with the Calaveras Fault, a NNW trending strike slip fault, which.has experienced similar size-historic events.
Personnel at the Vallecitos General Electric Test Reactor (about 50 km
, northwest of the epicenter) felt the event, inspected and found no damage.
The Aerotest Operations Test Reactor (about 60 km northwest of the epi-center) felt.the event and manually scrammed _the reactor, although there was no actuation of strong motion instruments. At the Diablo Canyon nuclear power plant (about 230 km-south of the epicenter) the event was not felt. Recordings were made on a sensitive strong motion instrument.
The recordings are being analyzed, but the maximum acceleration appears to be less than 0.019 . The standard strong motion instrumentation did i not trigger. The event was not felt at Rancho Seco (over 100 km north of the epicenter).
Damage was reported.in the towns of Gilroy and Morgan Hill. Both towns are about 5 to 10 km southwest of the Calaveras. Fault. Houses in hilly terrain were thrown off their foundations. A fire was attributed to a l
ruptured gas line ignited at an auto repair shop in San Jose.
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Richard H. Vollmer No ground rupture has been observed. The earthquake cracked the pavement atop Anderson Dam, which is close to the Calaveras. Engineers inspected the dam and saw no concern. A bridge east of Morgan Hill was knocked from its foundation and suffered serious damage. In San Francisco (about 100 km northwest of the epicenter) skyscrapers swayed and windows broke.
Presently there is no reported damage to industrial facilities.
About 125 aftershocks have been recordad,, but most were not felt. Field teams from the USGS and the California Division of Mines and Geology are presently surveying the damage, looking for evidence of surface rupture, checking strong motion accelerometer stations for possible recordings, and installing portable seismometers. ,
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Robert E. Jackson, Chief Geosciences Branch Division of Engineering cc: H. Denton E. Case D. Eisenhut J. Knight G. Lear -
G. Lainas T. Novak
- L. Beratan H.-denrilling F. Ingram J.' Martin, R-V GSB staff 6
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