Seismicity in the twenty years preceding the Loma Prieta California Earthquake

Geophysical Research Letters
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Abstract

Persistent seismicity occurred at a low rate during at least the twenty years before the Loma Prieta earthquake along the 60 km-long rupture zone. The depth distribution of this seismicity forms a broad “U”-shape that delineates the previously locked rupture zone. Relocations of seismicity during the ten years before the earthquake relative to the Loma Prieta aftershocks show that this “U”-shaped distribution can be partitioned lengthwise into activity on two adjacent subparallel structures: a vertical fault beneath the San Andreas fault trace and an eastward-dipping blind fault beneath the Sargent fault trace. The 11–18 km deep, southwest-dipping part of the Loma Prieta rupture was not active during at least the preceding ten years. The slip geometry of intersecting fault structures in this zone could contribute to both the preparation process and the complexity of the rupture.

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Publication type Article
Publication Subtype Journal Article
Title Seismicity in the twenty years preceding the Loma Prieta California Earthquake
Series title Geophysical Research Letters
DOI 10.1029/GL017i009p01429
Volume 17
Issue 9
Year Published 1990
Language English
Publisher American Geophysical Union
Description 4 p.
First page 1429
Last page 1432
Country United States
State California
Other Geospatial Loma Prieta, San Andreas Fault
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