HR: 17:15h
AN: S42H-06    [PDF]
TI: Nonlinear Dynamic Rupture Inversion of the 2000 Western Tottori, Japan, Earthquake
AU: * Olsen, K B
EM: kbolsen@crustal.ucsb.edu
AF: Institute for Crustal Studies, University of California at Santa Barbara, Santa Barbara, CA 93106-1100 United States
AB: Such inversion has traditionally been carried out kinematically, which has some important limitations, in particular unphysical constraints on the rupture velocity and the choice of source-time function. A more physically correct inversion would therefore take into account the dynamics of the rupture, i.e., the stress, and friction parameters. While the radiated waves are highly sensitive to the distribution of stress and friction parameters on the fault, an essential requirement for the inversion to work, such inversion is highly complicated due to the strong nonlinearity of the dynamic problem. We have developed a fully systematic, nonlinear inversion method to estimate dynamic rupture parameters using a Neighbourhood algorithm and a finite-difference technique for the forward modeling. The method provides an objective means of routinely estimating dynamic rupture parameters for large earthquakes. We test the method by estimating the initial stress within 32 regions on the causative fault for the 2000 M6.6 Western Tottori, Japan, earthquake. The synthetics for the dynamic models with the smallest misfit provide a good fit to 0.5 Hz strong motion data recorded at 12 near-field stations. The dynamic models with the smallest misfit agree with the slip distributions from conventional kinematic analyses in the location of the largest asperity. In the surrounding areas on the fault, where kinematic inversions generally produce only one, final model, our method provides an ensemble of nearly equally acceptable rupture models.
DE: 7209 Earthquake dynamics and mechanics
DE: 7212 Earthquake ground motions and engineering
DE: 7215 Earthquake parameters
DE: 7260 Theory and modeling
SC: Seismology [S]
MN: 2003 Fall Meeting