HR: 0800h
AN: G51B-0819    [Abstracts]
TI: Inversion Analysis of Postseismic Deformation in Poroelastic Material Using Finite Element Method
AU: * Kawamoto, S
EM: satoshi@eps.nagoya-u.ac.jp
AF: Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chigusa-ku, Nagoya, 464-8602 Japan
AU: Ito, T
G51B-0819 AF: Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chigusa-ku, Nagoya, 464-8602 Japan
AU: Hirahara, K
G51B-0819 AF: Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502 Japan
AB: Following a large earthquake, postseismic deformations in the focal source region have been observed by several geodetic measurements. To explain the postseismic deformations, researchers have proposed some physical mechanisms known as afterslip, viscoelastic relaxation and poroelastic rebound. There are a number of studies about postseismic deformations but for poroelastic rebound. So, we calculated the postseismic deformations caused by afterslip and poroelastic rebound using modified FEM code _eCAMBIOT3D_f originally developed by Geotech. Lab. Gunma University, Japan (2003). The postseismic deformations caused by both afterslip and poroelastic rebound are characteristically different from those caused only by afterslip. This suggests that the slip distributions on the fault estimated from geodetic measurements also change. Because of this, we developed the inversion method that accounts for both afterslip and poroelastic rebound using FEM to estimate the difference of slip distributions on the fault quantitatively. The inversion analysis takes following steps. First, we calculate the coseismic and postseismic response functions on each fault segment induced by the unit slip. Where postseismic response function indicate the poroelastic rebound. Next, we make the observation equations at each time step using the response functions and estimate the spatiotemporal distribution of slip on the fault. In solving this inverse problem, we assume the slip distributions on the fault are smooth in space and time except for rapid change (coseismic change). Because the hyperparameters that control the smoothness of spatial and temporal distributions of slip are needed, we determine the best hyperparameters using ABIC. In this presentation, we introduce the example of analysis results using this method.
DE: 0545 Modeling (4255)
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 7200 SEISMOLOGY
SC: Geodesy [G]
MN: Fall Meeting 2005