HR: 11:20h
AN: S42B-04 INVITED     [Abstracts]
TI: Using Regional Seismicity to Forecast Large Earthquakes
AU: * Sammis, C G
EM: sammis@usc.edu
AF: University of Southern California, Department of Earth Sciences, Los Angeles, CA 90089 0740 United States
AB: It is generally accepted that each earthquake changes the probability of successive earthquakes in a region the size of which scales with its magnitude, the shape of which is determined by its focal mechanism, and by an amount that can be estimated using the Gutenberg-Richter magnitude distribution and the Omori law for the rate of aftershocks, where aftershocks are allowed to be larger than the mainshock. This epidemic type aftershock (ETAS) model forms the basis of many current probabilistic earthquake prediction schemes. Inherent in these models is the assumption that the probability of a large earthquake is completely determined by the sum of stresses transferred by prior earthquakes. The question we address here is whether this assumption is true and, if not, is it possible to make forecasts that are statistically better than ETAS. For example, is there a critical state of stress in the crust that makes a large earthquake more likely and can we use seismicity to identify such a state? Another relevant question is whether large earthquakes are mechanically different from small earthquakes in a way that affects their forecasting? Is accelerating moment release observed before many large events an upward cascade predicted by the ETAS model, or evidence that the crust is approaching a critical state? Finally, are the ETAS predictions affected by the structure of the fault network and the interaction of this network with a more ductile lower crust?
DE: 7209 Earthquake dynamics (1242)
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
SC: Seismology [S]
MN: Fall Meeting 2005