CSMIP Strong-Motion Records from the Palm Springs, California Earthquake of 8 July 1986

OSMS 86-05

by M.J. Huang, R.W. Sherburne, D.L. Parke and A.F. Shakal

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Introduction

Strong motion records were recovered at over thirty stations of the California Strong Motion Instrumentation Program (CSMIP) following the earthquake of 8 July 1986 which occurred approximately 18 km north of Palm Springs. In total, records were recovered from 21 free-field stations, 8 buildings, 2 earth dams and one power plant. In addition to these records recovered by CSMIP, records were also recovered by such agencies as the U.S. Geological Survey and the University of Southern California.

Current estimates of the earthquake location and magnitude are (K. Hutton, CIT, personal communication):
           Hypocenter: 33.998 N, 116.607 W, 12 km depth. Magnitude: 5.9 ML
           Origin Time: 09:20: 45 GMT (02:20:45 PDT), 8 July 1986.

Surface faulting was observed in the epicentral area (E. Hart, personal communication). A total of about 7 cm of predominantly right-lateral strike-slip displacement was observed on the Banning Fault, a branch fault of the San Andreas Fault. The displacement observed was distributed over several parallel fault strands crossing Highway 62. Minor rupture was also observed on the Mission Creek Fault and along a branch fault at the mouth of Whitewater Canyon.

Serious damage was reported at an electric power substation near Devers Hill, and at the Whitewater Interstate 10 overpass west of North Palm Springs.