Seismicity in the twenty years preceding the Loma Prieta, California earthquake

Journal Article · Wed Aug 01 04:00:00 EDT 1990 · Geophysical Research Letters (American Geophysical Union); (USA)

DOI:https://doi.org/10.1029/GL017i009p01429· OSTI ID:6400527

Olson, J A ^[1]

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1. Geological Survey, Menlo Park, CA (USA)

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.

• OSTI ID: 6400527
• Journal Information: Geophysical Research Letters (American Geophysical Union); (USA), Journal Name: Geophysical Research Letters (American Geophysical Union); (USA) Vol. 17:9; ISSN GPRLA; ISSN 0094-8276
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CALIFORNIA
DEPTH
DIMENSIONS
DISTRIBUTION
EARTHQUAKES
FAILURES
FEDERAL REGION IX
FORECASTING
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOMETRY
HISTORICAL ASPECTS
HYPOCENTERS
MATHEMATICS
MECHANICS
NORTH AMERICA
ROCK MECHANICS
RUPTURES
SEISMIC EVENTS
SEISMICITY
SPACE DEPENDENCE
TIME DEPENDENCE
USA