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Three-dimensional P and S velocity structure in the Coalinga Region, California

Journal of Geophysical Research

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Abstract

The Coalinga earthquake sequence of 1983 provided a unique opportunity to perform a three-dimensional velocity and hypocenter inversion in an area of complex three-dimensional structure dominated by folding and blind thrusts. Inversion of 7696 P and 1511 S first arrivals from earthquakes and 696 P first arrivals from refraction shots produced a three-dimensional velocity model with grid spacing of 1-2 km in the hypocentral area. The overall shape and location of velocity features correspond well to the mapped surface geology. There is a linear high-velocity body (6.1-6.5 km/s), about 25 km long, from 6 to 8 km depth, that may represent a fragment of Coast Range ophiolite. A shallow low-velocity zone (LVZ), which extends for 20 km along the fold axis at about 6 km depth and correlates with LVZs observed in both the refraction and the reflection data, may indicate high pore pressure caused by lateral compressive strain, Deeper LVZs occur within inferred Franciscan material and may represent multiple thrust faults. -from Author

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Three-dimensional P and S velocity structure in the Coalinga Region, California
Series title:
Journal of Geophysical Research
Volume
95
Issue:
B10
Year Published:
1990
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article