HR: 0800h
AN: S11C-0710    [Abstracts]
TI: Dependence of the Omori-Utsu law parameters on mainshock magnitude: observations and modeling
AU: * Hainzl, S
EM: hainzl@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Marsan, D
EM: david.marsan@univ-savoie.fr
AF: Laboratoire de Geophysique Interne et Tectonophysique, Universite de Savoie, Le Bourget du Lac, F-73376, France
AB: We examine the dependence on m of the p and χ parameters appearing in Omori-Utsu formula λ(t,m)=χ×(t+c)^-p relating the rate of aftershocks λ at time t after a mainshock of magnitude m. Observations point out to a significant increase of p with m, along with a scaling relationship of the form χ~ 10^{α m}. We here show that these observations can be explained within the framework of the rate-and-state friction model, when accounting for realistic levels of co-seismic stress heterogeneity on the main fault. We constrain the model parameters in order to recover the trends observed in previous and new analyses of aftershock sequences. Finally, the influence of afterslip on parameters p and χ is studied, to highlight the fact that it can significantly perturb the p(m) and χ(m) relations obtained with the initial afterslip-free model.
DE: 7209 Earthquake dynamics (1242)
DE: 7215 Earthquake source observations (1240)
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