Variation of P-wave velocity before the Bear Valley, California, earthquake of 24 February 1972

R. Robinson; R. L. Wesson; W.L. Ellsworth

doi:10.1126/science.184.4143.1281

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Variation of P-wave velocity before the Bear Valley, California, earthquake of 24 February 1972

R. Robinson·R. L. Wesson·W.L. Ellsworth

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Abstract

Residuals for P-wave traveltimes at a seismograph station near Bear Valley, California, for small, precisely located local earthquakes at distances of 20 to 70 kilometers show a sharp increase of nearly 0.3 second about 2 months before a magnitude 5.0 earthquake that occurred within a few kilometers of the station. This indicates that velocity changes observed elsewhere premonitory to earthquakes, possibly related to dilatancy, occur along the central section of the San Andreas fault system.

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Source-reported bounding extent: 38.43780040863717° to 38.48735887611156° latitude; -120.0718612189573° to -120.00672664440306° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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R. Robinson, R. L. Wesson, W.L. Ellsworth. 1974. Variation of P-wave velocity before the Bear Valley, California, earthquake of 24 February 1972. https://doi.org/10.1126/science.184.4143.1281

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