The October 17, 1989, Loma Prieta, California, earthquake and its aftershocks: Geometry of the sequence from high-resolution locations

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

DOI:https://doi.org/10.1029/GL017i009p01417· OSTI ID:6400547

Dietz, L D; Ellsworth, W L ^[1]

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

Hypocenters of the Loma Prieta sequence form a dipping zone that rises from the mainshock hypocenter and is parallel to the mainshock nodal plane. Most aftershocks cluster around the perimeter of the zone, surrounding a relatively aseismic center which approximates the region of mainshock rupture. At its southeastern end, the dipping aftershock zone warps into a vertical surface that corresponds to the San Andreas fault. In the central and northwestern parts of the zone at depths above {approximately}10 km, the aftershocks define numerous disjoint fault structures. The large component of reverse-slip observed in this event agrees with a simple model for slip on a dipping plane within a compressional fault bend. The authors do not believe that the Loma Prieta earthquake occurred on the Sargent fault. However, they are unable to conclude whether it ruptured the principal plate boundary fault or a less frequently active fault.

• OSTI ID: 6400547
• Journal Information: Geophysical Research Letters (American Geophysical Union); (USA), Vol. 17:9; ISSN 0094-8276
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CALIFORNIA
EARTHQUAKES
HYPOCENTERS
AFTERSHOCKS
DEPTH
EARTHQUAKE MAGNITUDE
GEOLOGIC FAULTS
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
ROCK MECHANICS
RUPTURES
SEISMIC SOURCES
SPACE DEPENDENCE
TECTONICS
TIME DEPENDENCE
DIMENSIONS
FAILURES
FEDERAL REGION IX
GEOLOGIC FRACTURES
MECHANICS
NORTH AMERICA
SEISMIC EVENTS
USA
580000* - Geosciences