HR: 17:45h
AN: S32F-08    [PDF]
TI: Stress transfer and aftershocks
AU: * Shcherbakov, R
EM: roshch@physics.ucdavis.edu
AF: Center for Comp. Sci. & Eng., University of California, Davis, CA 95616 United States
AU: Turcotte, D L
EM: turcotte@geology.ucdavis.edu
AF: Department of Geology, University of California, Davis, CA 95616 United States
AU: Rundle, J B
EM: jbrundle@ucdavis.edu
AF: Center for Comp. Sci. & Eng., University of California, Davis, CA 95616 United States
AB: The earthquakes that are most readily associated with stress transfer are aftershocks. There are three important "laws" associated with aftershocks: (1) They satisfy Gutenberg-Richter frequency-magnitude scaling, (2) they decay in time according to Omori's law, and (3) they satisfy Bath's law. Bath's law states that the difference in magnitude between main shocks and their largest aftershocks is approximately constant, independent of the main shock magnitude. We propose a modified form of Bath's law by extrapolating the frequency-magnitude statistics of measured aftershocks of a given main shock to infer the largest aftershock. We consider eight earthquakes that occurred in southern and Baja California between 1987 and 2002 with magnitudes equal to or greater than 5.5. The difference in magnitude between main shock and largest aftershocks were 1.23+0.046 (Bath's law) and the difference in magnitude between main shock and inferred largest aftershocks were 1.21+0.27 (our modified Bath's law). We show that the applicability of the modified Bath's law implies that the fractional stress transfer responsible for aftershocks is a constant independent of main shock magnitude and that this scaling varies by about 25%. We find that about 95% of the energy dissipation due to an earthquake is associated with the main shock and 5% with the aftershocks.
DE: 7209 Earthquake dynamics and mechanics
DE: 7223 Seismic hazard assessment and prediction
DE: 8164 Stresses--crust and lithosphere
SC: Seismology [S]
MN: 2003 Fall Meeting