ML20209B317
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DI RIBUTION:
NTRAL FILE SB RDG March 22, 1982
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4 MEMORANDUM FOR:
Robert E. Jackson, Chief Geosciences Branch, DE 4
THRU:
Leon Reiter. Leader 1
NO.
Seismology Section, GSB, DE Z
88
-y FROM:
Robert L. Rothman, Seismologist Seismology Section, GSB, DE 6
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SUBJECT:
SMALL EARTHCUAKE NEAR DIABLO CAtlV0N NUCLEAR DOWER N
8LANT (DCN#8) 14 MARCH 1982 On 14 March 1982 there was a small earthquake near (15 to 20 km) DCriDo.
USGS - Denver Origin Time:
09:58:47.9Z M, = 3.5 0
Datitude:
35.08N, Longitbde 120.79 W Depth 5 km University of CA - Berkeley 09 58:52 Mr = 3 5 Origin Time:
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Latitude 35 11.7' (35.195 )N, Longitude 220 37.3' (120.622')W Depth 11 km felt in Arroyo Grande and San Luis %1spo Cal Inst. Tech Date was not good enough for them to release the location they calculated.
l The earthquake was not felt at DCNoo but was felt by two DGE employees at home in Arroyo Grande. The main strong motion instruments at DCN88 (Kinemetrics l
System) did not trigger but the Supplemental system (Terra Tech DCS 302) did trigger. The supplemental system has a much lower triggering level than the Kinemetrics System. Three free-field and three base of containment triaxial systems were played back. The largett peak acceleration recorded was in the
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free field and was 0.0004g. A signal was visible above the background noise for I
about 10 seconds. The other signals both free field and containment base were less than this signal in amplitude.
Earthquakes of this type are not unconsnon in the region and it is obvious from the low horizontal peak acceleration that they offer no danger to the plant.
h
,l N Rober
. Rothman, Seismologist
! L 820407OOCENB20322 Seismology Section "E
Geosciences Branch l
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