HR: 09:45h
AN: NG31A-08    [Abstracts]
TI: Scaling Properties of Aftershock Sequences
AU: * Shcherbakov, R
EM: roshch@cse.ucdavis.edu
AF: Center for Computational Science and Engineering, University of California, One Shields Ave., Davis, CA 95616 United States
AU: Yakovlev, G
EM: gleb@cse.ucdavis.edu
AF: Center for Computational Science and Engineering, University of California, One Shields Ave., Davis, CA 95616 United States
AU: Turcotte, D L
EM: turcotte@geology.ucdavis.edu
AF: Department of Geology, University of California, One Shields Ave., Davis, CA 95616 United States
AU: Rundle, J B
EM: rundle@cse.ucdavis.edu
AF: Center for Computational Science and Engineering, University of California, One Shields Ave., Davis, CA 95616 United States
AB: In this work the scaling properties of several aftershock sequences in California are studied using the framework of scaling analysis. The occurrence of aftershocks is an outcome of complex nonlinear threshold dynamics in the brittle part of the Earth's crust. This dynamics is a combined effect of different processes taking place in a highly heterogeneous media over a wide range of scales. In the temporal domain the decay of aftershock rates can be described by the generalized Omori's law, which incorporates three empirical laws: the Gutenberg-Richter relation for frequency-magnitude scaling, the modified Omori's law for the temporal decay of aftershocks, and the modified Bath's law for the difference between the magnitudes of a main shock and its "largest" aftershock. The analysis of decay rates suggests that the parameter c in the generalized Omori's law is not a constant but scales with the lower magnitude cutoff and plays the role of a characteristic time in the establishment of Gutenberg-Richter scaling. Distributions of inter-occurrence times between earthquakes in aftershock sequences are analyzed and a model based on a non-homogeneous Poisson (NHP) process is proposed to quantify the observed scaling. In this model the generalized Omori's law for the decay of aftershocks is used as a time-dependent rate in the NHP process. The formula describing the distribution of inter-occurrence times between events in NHP process over a finite time period T is derived and confirmed by numerical simulations. This analytically derived distribution of inter-occurrence times is applied to several major aftershock sequences in California to confirm the validity of the proposed hypothesis. It is argued that the NHP process combined with the generalized Omori's law can be used to a good approximation to quantify the observed temporal scaling of inter-occurrence times between earthquakes in aftershock sequences.
DE: 3265 Stochastic processes (3235, 4468, 4475, 7857)
DE: 4468 Probability distributions, heavy and fat-tailed (3265)
DE: 4475 Scaling: spatial and temporal (1872, 3270, 4277)
DE: 7260 Theory
DE: 7290 Computational seismology
SC: Nonlinear Geophysics [NG]
MN: Fall Meeting 2005