HR: 14:40h
AN: S13E-05 INVITED    [Abstracts]
TI: Model-Independent Stochastic Declustering
AU: Marsan, D
EM: david.marsan@univ-savoie.fr
AF: LGIT, Universite de Savoie, Le Bourget du Lac, 73376, France
AU: * Lengline, O
EM: olivier.lengline@univ-savoie.fr
AF: LGIT, Universite de Savoie, Le Bourget du Lac, 73376, France
AB: Earthquakes, whatever their size, can trigger other earthquakes. For example, large mainshocks are followed by aftershocks, which then in turn activate their own local aftershock sequences, and so on. This results in a cascade of triggering, so that the event initiating this chain can indirectly be the cause of many more earthquake occurrences than what it directly triggered, hence extending its reach through multiple triggering. A long-lasting difficulty is to determine, from earthquake data, which events are directly, indirectly, or not at all, connected together. Here we demonstrate that this can be done in a probabilistic way, with no a priori model nor arbitrary parameterization. It is found that even large regional earthquakes (the 1992, Mw7.3 Landers and 1999, Mw7.1 Hector Mine earthquakes in California) have a surprisingly short direct triggering influence (of the order of 10 days for M3+ aftershocks), which is then very substantially extended (by a factor of ~ 100) in duration through multiple triggering. These results show that cascade triggering is a key component in earthquake interactions, and must therefore be accounted for in probabilistic earthquake prediction and seismic hazard assessment.
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: 2007 Fall Meeting