A time-dependent probabilistic seismic-hazard model for California

For the purpose of sensitivity testing and illuminating nonconsensus compon ents of time-dependent models, the California Department of Conservation, D ivision of Mines and Geology (CDMG) has assembled a time-dependent version of its statewide probabilistic seismic hazard (PSH) model for California. T he model incorporates available consensus information from within the earth -science community, except for a few faults or fault segments where consens us information is not available. For these latter faults, published informa tion has been incorporated into the model. As in the 1996 CDMG/U.S. Geologi cal Survey (USGS) model, the time-dependent models incorporate three multis egment ruptures: a 1906, an 1857, and a southern San Andreas earthquake. Se nsitivity:tests are presented to show the effect on hazard and expected dam age estimates of (1) intrinsic (aleatory) sigma, (2) multisegment (cascade) vs. independent segment (no cascade) ruptures, and (3) time-dependence vs, time-independence. Results indicate that (1) differences in hazard and exp ected damage estimates between time-dependent and independent models increa se with decreasing intrinsic sigma, (2) differences in hazard and expected damage estimates between full cascading and not cascading are insensitive t o intrinsic sigma, (3) differences in hazard increase with increasing retur n period (decreasing probability of occurrence), and (4) differences;in mom ent-rate budgets increase with decreasing intrinsic sigma and with the degr ee of cascading, but are within the expected uncertainty in PSH time-depend ent modeling and do not always significantly affect hazard and expected dam age estimates.