HR: 1340h
AN: NG43B-0573    [Abstracts]
TI: Numerical Born kernels to account for finite-frequency effects in surface wave tomography
AU: * Peter, D B
EM: dpeter@erdw.ethz.ch
AF: Institute of Geophysics ETH, Schafmattstr. 30, Zurich, 8093 Switzerland
AU: Boschi, L
EM: lapo@erdw.ethz.ch
AF: Institute of Geophysics ETH, Schafmattstr. 30, Zurich, 8093 Switzerland
AB: In order to conduct seismic tomography, one should use the most adequate description of wave propagation; thus far, almost all tomographic models rely on ray theory, a high-frequency approximation. Particularly for surface waves, Born theory, a single scattering theory, improves it by taking first order scattering effects into account. The resulting sensitivity kernels are typically derived from analytical far-field Green's tensors, which lead to singularities at source and receiver locations; numerical derivation of kernels in contrast can avoid this, but full numerical integration of the equations of motion in 3D is computationally too expensive when implemented on a realistic 3-D Earth. If we restrict ourselves to the case of a smooth, laterally heterogeneous Earth, we can use a 0-thickness membrane as an analogue for Love and Rayleigh wave propagation, speeding up dramatically the numerical integration. Here, following earlier work by Tanimoto (1990) and Tape (2003), we implement ``membrane waves'' with a new finite-difference algorithm that accounts for finite-frequency effects in the smooth Earth approximation; thus leading to the numerical derivation of Born sensitivity kernels for surface wave phase velocity tomography.
DE: 7255 Surface waves and free oscillations
DE: 7270 Tomography (6982, 8180)
DE: 7290 Computational seismology
SC: Nonlinear Geophysics [NG]
MN: Fall Meeting 2005