Full waveforms are inverted using two global optimization methods, a genetic algorithm and simulated annealing. The inversion scheme is based on a finite-difference solution of the 2-D elastic wave equation in the time-distance domain. The strength of this approach is the ability to generate all possible wave types (body waves and surface waves, etc.) and thus to simulate complex seismic wavefields that are then compared with observed data to infer subsurface properties. The capability of this inversion technique is tested herein with synthetic data sets. The inversion results show the ability of characterizing both low- and high-velocity layers in laterally inhomogeneous profiles. Based upon the cases presented, coupling of global optimization with full waveforms is computationally practical, as the results presented herein were all achieved in a few hours of computer time on a standard laptop computer.
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