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Evidence of shallow fault zone strengthening after the 1992 M7.5 Landers, California, earthquake

Science

By:
, , , ,
DOI: 10.1126/science.279.5348.217

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Abstract

Repeated seismic surveys of the Landers, California, fault zone that ruptured in the magnitude (M) 7.5 earthquake of 1992 reveal an increase in seismic velocity with time. P, S, and fault zone trapped waves were excited by near-surface explosions in two locations in 1994 and 1996, and were recorded on two linear, three-component seismic arrays deployed across the Johnson Valley fault trace. The travel times of P and S waves for identical shot-receiver pairs decreased by 0.5 to 1.5 percent from 1994 to 1996, with the larger changes at stations located within the fault zone. These observations indicate that the shallow Johnson Valley fault is strengthening after the main shock, most likely because of closure of cracks that were opened by the 1992 earthquake. The increase in velocity is consistent with the prevalence of dry over wet cracks and with a reduction in the apparent crack density near the fault zone by approximately 1.0 percent from 1994 to 1996.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Evidence of shallow fault zone strengthening after the 1992 M7.5 Landers, California, earthquake
Series title:
Science
DOI:
10.1126/science.279.5348.217
Volume
279
Issue:
5348
Year Published:
1998
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Science
First page:
217
Last page:
219
Number of Pages:
3