Application of simulated annealing to inversion of surface wave phase velocity

摘要

Applicability of simulated annealing to inversion of surface wave phase velocity that is commonly used in microtremor array exploration is investigated in this study. Numerical experiments using a 4-layer model of sedimentary layers indicate that the inversion method is effective in the Rayleigh wave phase velocity inversion. We compare the performances of very fast simulated annealing (VFSA) inversion with another inversion method based on genetic algorithms (GA) by Yamanaka and Ishida (1995). The GA inversion can find near-optimal models with less computational costs than that required in the VFSA inversion. However, inverted model from the VFSA inversion has less error than that from the GA inversion. This means that the VFSA inversion can find models that are much closer to the global minimum solution because of high ability in global and local searches. We, then, apply the VFSA method to actual phase velocity data and determine S-wave profiles.