HR: 1330h
AN: S12B-0390    [PDF]
TI: Paleoseismologic Evidence for Long-Distance and Long-Term Elastic Interactions in Southern California
AU: * Dolan, J F
EM: dolan@earth.usc.edu
AF: Dept. of Earth Sciences, University of Southern California, Los Angeles, CA 90089-0740 United States
AU: Bowman, D D
EM: dbowman@fullerton.edu
AF: Dept. of Geological Sciences, California State University, Fullerton, Fullerton, CA 92834-6850 United States
AU: Sammis, C G
EM: sammis@earth.usc.edu
AF: Dept. of Earth Sciences, University of Southern California, Los Angeles, CA 90089-0740 United States
AB: Paleoseismologic data reveal four temporal clusters of large earthquakes in the Los Angeles region during the past 12,000 years. The 200-year-long historic period in Los Angeles is part of the most recent, and ongoing, lull between earthquake clusters. The Los Angeles-region clusters are temporally anti-correlated with similar seismic clusters along the Eastern California Shear Zone and the Garlock fault in the Mojave Desert. These three fault systems serve collectively to accommodate N-S compression across the Big Bend region of the SAF. Simple elastic models demonstrate that motion on the Los Angeles-region fault network moves the Garlock and ECSZ faults away from failure, and vice versa. This slight unloading of the faults, combined with a non-linear response, will cause the system to evolve towards the observed out-of-phase behavior, even if the two parts of the system are initially in phase. These results suggest that long-distance elastic strain interactions exert a first-order control on earthquake occurrence on the scale of the entire plate boundary. Moreover, these data indicate that seismic slip on regional fault systems is not a temporally and spatially random process, thus calling into question Poissonian models of seismic hazard assessment.
DE: 7221 Paleoseismology
DE: 7230 Seismicity and seismotectonics
SC: Seismology [S]
MN: 2003 Fall Meeting