HR: 1330h
AN: S42D-0194    [PDF]
TI: Stochastic Model of Complexity in Earthquake Slip Distributions
AU: * Lavallee, D
EM: daniel@crustal.ucsb.edu
AF: Institute for Crustal Studies, University of California, Santa Barbara, CA 93106 United States
AU: Liu, P
EM: pcliu@crustal.ucsb.edu
AF: Institute for Crustal Studies, University of California, Santa Barbara, CA 93106 United States
AU: Archuleta, R J
EM: ralph@crustal.ucsb.edu
AF: Institute for Crustal Studies, University of California, Santa Barbara, CA 93106 United States
AB: Finite-fault source inversions reveal the spatial complexity of earthquake slip or prestress distribution over the fault surface. The basic assumption of this study is that a stochastic model can reproduce the variability in amplitude and the long-range correlation of the slip spatial distribution. The model is tested for the 1992 Landers earthquake and the 1994 Northridge earthquake and the results are compared with the stochastic model derived for the 1979 Imperial Valley earthquake. For the three earthquakes, we show that the average power-spectra of the raw, i.e., non-interpolated, data follow a power law behavior with scaling exponents close to unity. For the three earthquakes, we have found that non-Gaussian distributions, i.e., the Levy distributions, are better suited to describe the spatial variability of slip over the fault. The values of the Levy parameters differ from one earthquake to the other. We discuss the variation in parameter values from one earthquake to another and its signification for earthquake properties. We also show that a stochastic characterization of the slip amplitude based on a Gaussian distribution fails to reproduce the spatial variability observed in the original slip distribution. Especially, the "extreme" large slip values-frequently defined as asperities-are present in the synthetic slip amplitude based on a Levy distribution but are missing in their Gaussian counterpart. The results obtained for the Imperial Valley, Landers and Northridge earthquakes suggest that some features of the slip spatial complexity are universal and can be modeled accordingly. If this is proven correct, this will imply that the spatial variability and the long-range correlation of any slip or stress distribution can be described with the help of five parameters: a scaling exponent controlling the spatial correlation and the four parameters of the Levy distribution constraining the spatial variability.
DE: 3210 Modeling
DE: 7209 Earthquake dynamics and mechanics
DE: 7215 Earthquake parameters
DE: 7260 Theory and modeling
DE: 8168 Stresses--general
SC: Seismology [S]
MN: 2003 Fall Meeting