HR: 1340h
AN: S13A-0178    [Abstracts]
TI: Triangular Spectral Element simulation of 2D elastic wave propagation using unstructured triangular grids
AU: * Mercerat, D
EM: mercerat@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Vilotte, J
EM: vilotte@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Sanchez-Sesma, F
EM: sesma@servidor.unam.mx
AF: Instituto de Ingenieria, UNAM, Coyaacam 04510, Mexico DF, 04510 Mexico
AB: Many problems in geophysics need to infer parameter distributions of the earth's interior from information provided by seismic wave propagation through complex media. Numerical simulations of earthquake-induced wave propagation within heterogeneous geological structures, have also important implications in terms of earthquake risk assessment and strong motion predictions. The development of new seismic interpretation methods requires accurate numerical modeling tools for the simulation of the complete wave field in heterogeneous media with complex geometries. Recent developments toward high-order numerical simulation of seismic wave propagation have been based on Spectral Element Method (SEM). Spectral elements add some geometrical flexibility to classical spectral or pseudo-spectral methods, while retaining the spatial exponential convergence for locally smooth solutions with quasi-optimal dispersion errors, and allow accurate resolution of evanescent interface and surface waves. Moreover spectral elements are much easier to implement than global spectral methods on today's generation parallel computers, which involve non uniform distributed access to the memory. However classical SEM are restricted to quadrilateral subdomains. Geometrical flexibility is especially important in computational seismology, at regional and local scales, when dealing with complex scattering phenomena and complex multi-scale geological structures. Today's such a flexibility is hardly achieved when using classical SEM and higher geometrical flexibility is therefore a strong motivation for exploring the use of triangular elements and unstructured meshes. A Triangular Spectral Element Method (TSEM) is presented for elastic wave propagation using unstructured triangulation of the domain. TSEM makes use of a variational formulation of elastodynamics based on unstructured straight-sided triangles that allow enhanced geometrical flexibility. Comparisons with classical SEM show similar accuracy and long term stability. Surface and interface waves are shown to be accurately modeled even in the case of complex topography with TSEM. Numerical results are presented for 2D canonical examples as well as more realistic problems such as the 2D elastic wave scattering by cylindrical cavities embedded in an elastic half-space. On going extensions will be presented for elastic wave propagation both in the frequency and time domains.
DE: 0500 COMPUTATIONAL GEOPHYSICS (3200, 3252, 7833)
DE: 7203 Body waves
DE: 7255 Surface waves and free oscillations
DE: 7260 Theory
DE: 7290 Computational seismology
SC: Seismology [S]
MN: Fall Meeting 2005