Bulletin of the Seismological Society of America; June 2009; v. 99; no. 3;
p. 1760-1785; DOI: 10.1785/0120080253
© 2009 Seismological Society of America
A Viscoelastic Earthquake Simulator with Application to the San Francisco Bay Region
Fred F. Pollitz
USGS, Menlo Park, California
Earthquake simulation on synthetic fault networks carries great potential for characterizing the statistical patterns of earthquake occurrence. I present an earthquake simulator based on elastic dislocation theory. It accounts for the effects of interseismic tectonic loading, static stress steps at the time of earthquakes, and postearthquake stress readjustment through viscoelastic relaxation of the lower crust and mantle. Earthquake rupture initiation and termination are determined with a Coulomb failure stress criterion and the static cascade model. The simulator is applied to interacting multifault systems: one, a synthetic two-fault network, and the other, a fault network representative of the San Francisco Bay region. The faults are discretized both along strike and along dip and can accommodate both strike slip and dip slip. Stress and seismicity functions are evaluated over 30,000 yr trial time periods, resulting in a detailed statistical characterization of the fault systems. Seismicity functions such as the coefficient of variation and a- and b-values exhibit systematic patterns with respect to simple model parameters. This suggests that reliable estimation of the controlling parameters of an earthquake simulator is a prerequisite to the interpretation of its output in terms of seismic hazard.
Copyright © 2009 by Seismological Society of America