题目：Frozen Gaussian Approximation Based Seismic Tomography
报告人：柴利慧 博士 （University of California， Santa Barbara）
摘要：We present a systematically introduction to the Frozen Gaussian Approximation (FGA) for high-frequency seismic tomography in 3-D earth models. In the frozen Gaussian approximation (FGA) we approximate the seismic wavefield by a summation of frozen (fixed-width) Gaussian wave-packets propagating along ray paths. One can use a relatively small number of Gaussians to get accurate approximations of the high-frequency wavefield. Meanwhile, FGA algorithm can be perfectly parallelized, which speeds up the computation drastically with a high-performance computing station. In order to apply FGA to the computation of 3-D high-frequency seismic tomography, first we reformulate the FGA so that one can efficiently compute the Green's functions; and second, we incorporate Snell's law into the FGA formulation, and asymptotically derive reflection, transmission and free surface conditions for FGA to compute high-frequency seismic wave propagation in high contrast media. We successfully apply FGA in the local earthquake inversion and cross-well inversion using travel-time tomography and full-waveform inversion. Our numerical tests show that FGA has a huge advantage in comparison with the classical direct solver such as spectral element method in improving the computational efficiency, parallelizability, and accuracy in the high-frequency regime and large domain simulation.
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