Fault-crossing P delays, epicentral biasing, and fault behavior in central California

Tectonophysics
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Abstract

The P delays across the San Andreas fault zone in central California have been determined from travel-time differences at station pairs spanning the fault, using off-fault local earthquake or quarry blast sources. Systematic delays as large as 0.4 sec have been observed for paths crossing the fault at depths of 5-10 km. These delays can account for the apparent deviation of epicenters from the mapped fault trace. The largest delays occur along the San Andreas fault between San Juan Bautista and Bear Valley and Between Bitterwater Valley and Parkfield. Spatial variations in fault behavior correlate with the magnitude of the fault-crossing P delay. The delay decreases to the northwest of San Juan Bautista across the "locked" section of the San Andreas fault and also decreases to the southeast approaching Parkfield. Where the delay is large, seismicity is relatively high and the fault is creeping. 

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Publication type Article
Publication Subtype Journal Article
Title Fault-crossing P delays, epicentral biasing, and fault behavior in central California
Series title Tectonophysics
DOI 10.1016/0040-1951(79)90275-0
Volume 52
Issue 1-4
Year Published 1979
Language English
Publisher Elsevier
Description 1 p.
First page 600
Last page 600
Country United States
State California
Other Geospatial central California
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