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Focal mechanism of the August 1, 1975 Oroville earthquake

Langston, Charles A. and Butler, Rhett (1976) Focal mechanism of the August 1, 1975 Oroville earthquake. Bulletin of the Seismological Society of America, 66 (4). pp. 1111-1120. ISSN 0037-1106.

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Long-period teleseismic P and S waves from the WWSS and Canadian networks are modeled to determine the focal parameters for the main shock in the Oroville earthquake series. Using the techniques of P first motions, wave-form synthesis, and phase identification, the focal parameters are determined as follows: dip 65°; rake −70°; strike 180°; depth 5.5 ± 1.5km; moment 5.7 ± 2.0 × 10^(24) dyne-cm; and a symmetric triangular time function 3 sec in duration. This is a north-south striking, westward dipping, normal fault with a small component of left-lateral motion. The time separation between the small foreshock and mainshock appears to be 6.5 sec at teleseismic distances, rather than 8.1 sec as observed at short distances.

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Additional Information:Copyright © 1976, by the Seismological Society of America. Manuscript received February 19, 1976. We would like to thank the numerous seismic station administrators throughout the world who took their valuable time to respond to our seismogram requests. We also would like to extend our gratitude to Don Helmberger and Tom Heaton for their critical reviews of the manuscript. This research was supported by the Advanced Research Projects Agency of the Department of Defense and was monitored by the Air Force Office of Scientific Research under Contract F44620-72-C-0078. One of the authors (R.B.) was supported by the Fannie and John Hertz Foundation.
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Advanced Research Projects Agency (ARPA)UNSPECIFIED
Air Force Office of Scientific Research (AFOSR)F44620-72-C-0078
Fannie and John Hertz FoundationUNSPECIFIED
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Caltech Division of Geological and Planetary Sciences2718
Issue or Number:4
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ID Code:48529
Deposited By: George Porter
Deposited On:14 Aug 2014 15:03
Last Modified:03 Oct 2019 07:04

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