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Earthquake Prediction: Variation of Seismic Velocities before the San Francisco Earthquake

Whitcomb, James H. and Garmany, Jan D. and Anderson, Don L. (1973) Earthquake Prediction: Variation of Seismic Velocities before the San Francisco Earthquake. Science, 180 (4086). pp. 632-635. ISSN 0036-8075. doi:10.1126/science.180.4086.632.

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A large precursory change in seismic body-wave velocities occurred before the earthquake in San Fernando, California. The discovery that this change is mainly in the P-wave velocity clearly relates the effect to the phenomenon of dilatancy in fluid-filled rocks. This interpretation is supported by the time-volume relation obtained by combining the present data with the data from previous studies. The duration of the precursor period is proportional to the square of an effective fault dimension, which indicates that a diffusive or fluid-flow phenomenon controls the time interval between the initiation of dilatancy and the return to a fully saturated condition which is required for rupture.

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Additional Information:© 1973 American Association for the Advancement of Science. Received 29 December 1972: revised 27 March 1973. We thank Y. P. Aggarwal, L. R. Sykes, J. Armbruster, and M. L. Sbar for a preprint of their paper. H. Kanamori made many useful contributions and reviewed the manuscript. Supported by U.S. Geological Survey contract 14-08-0001-12714 and by NASA contract 49-615-95650-0-3910 to the Jet Propulsion Laboratory. Contribution No. 2284, Division of Geological and Planetary Sciences, California Institute of Technology.
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Caltech Division of Geological and Planetary Sciences2284
Issue or Number:4086
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Official Citation:Earthquake Prediction: Variation of Seismic Velocities before the San Francisco Earthquake James H. Whitcomb, Jan D. Garmany, and Don L. Anderson Science 11 May 1973: 180 (4086), 632-635. [DOI:10.1126/science.180.4086.632]
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59055
Deposited By: Tony Diaz
Deposited On:29 Jul 2015 19:05
Last Modified:10 Nov 2021 22:14

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