Seismomagnetic Observation during the 8 July 1986 Magnitude 5.9 North Palm Springs Earthquake
Johnston MJ and Mueller RJ. 1987. Seismomagnetic Observation during the 8 July 1986 Magnitude 5.9 North Palm Springs Earthquake. Science. 237(4819):1201-1203
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 observations 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.
- Type
- Journal Article
- Authors
- Johnston, M; Mueller, R
- Units
- JOTR
- Keywords
- Active Faults, Aftershocks, arrays, Banning Fault, California, Deformation, Earthquakes, Engineering Geology, Faults, Field Studies, Geologic Hazards, Geology, Geophysical Surveys, magnetic anomalies, magnetic field, Magnetic Surveys, magnetometers, Magnitude, North Palm Springs earthquake 1986, Pacific Coast, Prediction, Riverside County, San Andreas Fault, San Bernardino County, Seismology, Sketch Map, Southern California, Stress, Strike Slip Faults, time variations, Western U.S.