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Science 4 September 1987:
Vol. 237. no. 4819, pp. 1201 - 1203
DOI: 10.1126/science.237.4819.1201
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Articles

Seismomagnetic Observation During the 8 July 1986 Magnitude 5.9 North Palm Springs Earthquake

M. J. S. JOHNSTON 1 and R. J. MUELLER 1

1 U.S. Geological Survey, Menlo Park, CA 94025.

A differentially connected array of 24 proton magnetometers has operated along the San Andreas fault since 1976. Seismomagnetic offsets of 1.2 and 0.3 nanotesla were observed at epicentral distances of 3 and 9 kilometers, respectively, after the 8 July 1986 magnitude 5.9 North Palm Springs earthquake. These seismomagnetic observation are the first obtained of this elusive but long-anticipated effect. The data are consistent with a seismomagnetic model of the earthquake for which right-lateral rupture of 20 centimeters is assumed on a 16-kilometer segment of the Banning fault between the depths of 3 and 10 kilometers in a region with average magnetization of 1 ampere per meter. Alternative explanations in terms of electrokinetic effects and earthquake-generated electrostatic charge redistribution seem unlikely because the changes are permanent and complete within a 20-minute period.

Submitted on April 22, 1987
Accepted on June 30, 1987


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Seismomagnetic Effects from the Long-Awaited 28 September 2004 M 6.0 Parkfield Earthquake.
M. J. S. Johnston, Y. Sasai, G. D. Egbert, and R. J. Mueller (2006)
Bulletin of the Seismological Society of America 96, S206-S220
   Abstract »    Full Text »    PDF »
Magnetic field observations in the near-field the 28 June 1992 Mw 7.3 Landers, California, earthquake.
M. J. S. Johnston, R. J. Mueller, and Y. Sasai (1994)
Bulletin of the Seismological Society of America 84, 792-798
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