HR: 08:30h
AN: S31A-03    [PDF]
TI: Detecting Seismicity Shadows at Short Time Scales
AU: * Marsan, D
EM: david.marsan@univ-savoie.fr
AF: LGIT Universite de Savoie, Campus Scientifique, Le Bourget du Lac, 73376 France
AB: Stress changes following the occurrence of an earthquake can lead to significant changes of the seismicity rate. While triggering (eg, aftershocks on the main fault) is clearly observed, regions of seismicity rate decrease can be harder to detect. We here address this detectability issue, which becomes particularly severe at short (eg days-weeks) time scales. A robust method is proposed in order to estimate the probability that a given region has experienced a seismicity rate decrease. This probability is generally (for large, recent California earthquakes) found to be low: seismicity shadows are significantly not as common as activated regions. The role of crustal heterogeneities in promoting triggering is discussed.
DE: 7209 Earthquake dynamics and mechanics
DE: 7223 Seismic hazard assessment and prediction
DE: 7230 Seismicity and seismotectonics
SC: Seismology [S]
MN: 2003 Fall Meeting