HR: 09:15h
AN: G21D-06 INVITED    [Abstracts]
TI: 3-D FEM derived elastic Green's functions for the coseismic and postseismic deformation of the 2005 Mw 8.7 Nias-Simeulue, Sumatra earthquake
AU: * Hsu, Y
EM: yaru@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, 128 Academia Rd, Sec. 2, Nankang, Taipei, 115, Taiwan
AU: Simons, M
EM: simons@caltech.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E California Blvd, MC252-21, Pasadena, CA 91125, United States
AU: Williams, C
EM: willic3@rpi.edu
AF: Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Jonsson-Rowland Science Center, 1W19 110 8th Street, Troy, NY 12180, United States
AU: Casarotti, E
EM: emanuele.casarotti @gmail.com
AF: Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E California Blvd, MC252-21, Pasadena, CA 91125, United States
AB: We adopt a finite element method to investigate the effect of 3D variation of material properties in the subduction zone using the coseismic and postseismic deformation of the 2005 Mw 8.7 Nias-Simeulue, Sumatra earthquake. In this study, we construct a simple subduction model using the mesh generation software, Cubit, developed by Sandia National Lab., USA. The fine element code, PyLith, is used to compute Green¡¦s function responses due to unit dislocation. To validate the FEM results, we compare simple modeling results between FEM and Okada analytic solutions. Preliminary analysis shows the difference of surface displacement calculated from homogeneous and 3-D heterogeneous material models can be as large as 20%. Ignoring the spatial variation of material properties leads to systematic misfits in surface horizontal and vertical displacements. Inverting fault slip distributions with assumption of a homogeneous, isotropic earth, results in biased fault slip distributions and fault geometries in our synthetic tests. For the coseismic and postseismic deformation of the Nias-Simeulu earthquake, we infer a model with less up-dip slip when using a more realistic 3-D elastic structure. We find the spatial variation of coseismic and postseismic slip distribution in various models remains similar, while integrated potency along depth in 3-D elastic models shift along the down-dip direction comparing with that in an elastic half-space model. The down-dip shift of maximum integrated potency along the depth depends on the material contrast in the fault zone. In addition, the impact of 3-D fault geometry seems to play a more important role comparing to the effect of heterogeneity.
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Geodesy [G]
MN: 2007 Fall Meeting