HR: 1340h
AN: S13A-0184    [Abstracts]
TI: A Simple Scheme for the Staggered FDM Computation of Seismic Waves for Full Anisotropic Media
AU: * Nakamura, T
EM: nakamura@geo.kyushu-u.ac.jp
AF: Kyushu University, Hakozaki 6-10-1, Fukuoka, 812-8581 Japan
AU: Takenaka, H
EM: takenaka@geo.kyushu-u.ac.jp
AF: Kyushu University, Hakozaki 6-10-1, Fukuoka, 812-8581 Japan
AU: Nishigami, K
EM: nishigam@eqh.dpri.kyoto-u.ac.jp
AF: Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, 611-0011 Japan
AB: A comprehensive picture of the seismic wave propagation in anisotropic media results from 21 independent elastic constants. In isotropy, two elastic constants are necessary to define the medium and in transversely isotropy five constants are necessary. Even in the case of the transversely isotropy, more than five constants must be defined when the symmetry axes are not uniform. From the stress-strain relation (Hooke_fs law), in computation of seismic waves for full anisotropic media, each component of the stress tensor is coupled with all components of the displacement gradient tensor. It is then difficult to directly applied the staggered FDM schemes used for isotropic cases to general anisotropic cases because some components of the displacement (or particle velocity) gradient tensor are not located at the grid points of the stress component. In order to solve this problem, some interpolation schemes have been additionally exploited to derive the desired quantity values at inter-grid points (e.g., Igel et al., 1995), where some care may be necessary to match the accuracy order of the interpolation schemes with that of the FDM. In this presentation we propose alternative approach to resolve this grid problem. We embed a simple differential identity into the government equations for elastic wave, which realize some first partial derivatives of the displacement (or particle velocity) in the equations by three sequential partial differentiations, so that we can avoid the grid problem applying the staggered FD schemes directly. We successfully implemented this approach with fortran and made a code for 3D seismic wave modeling. In this presentation we show the scheme of our new approach and some numerical examples to demonstrate its feasibility.
DE: 7200 SEISMOLOGY
DE: 7203 Body waves
DE: 7290 Computational seismology
SC: Seismology [S]
MN: Fall Meeting 2005