SIMILA, G. W., Department of Geological Sciences, California State Univ., Northridge, CA 91330; V. A. GALLARDO and K. McNALLY, Earth Sciences Department, University of California, Santa Cruz, CA 95064; M. L. BEGNAUD and D. S. STAKES, Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039

Abstract: New Investigation of Significant Monterey Bay Area Earthquakes (M=4.0+, 1926-79) Utilizing Data From a 1998 Portable Seismic Network and Master-Event Methods

During 1998, nine land-based PASSCAL Ref-Teks (3-component) were deployed along the coast of Monterey Bay from Pigeon Point to Carmel Valley to supplement the USGS network and supplement five ocean-bottom seismic (OBS) instruments deployed in the Monterey Bay as part of "Margin Seismology System Deployment Project" of the Monterey Bay Aquarium Research Institute (MBARI). Small well-recorded earthquakes from diverse source areas within the Bay have been used as a series of Master-Events to relocate a catalog of larger earthquakes from 1984-97. P and S wave travel times to historic UC Berkeley stations were thus "calibrated" for the various subareas within the Bay, and used to systematically relocate the largest historic Monterey Bay events (M=4-6.1) since 1926. Analysis of the Pasadena and Riverside Wood-Anderson amplitudes are used to compare relative sizes of the events. Our results suggest that most historic energy release at scattered locations found in the old catalog is real and these events can be confidently associated with the younger San Gregorio or older Monterey Bay fault zones.

AAPG Search and Discovery Article #90920©1999 AAPG Pacific Section Meeting, Monterey, California