Assessing Site and Path Effects by Full Waveform Modeling

We have developed a method to calculate site and path effects for complex heterogeneous media using synthetic Green's functions. The Green's functions are calculated numerically by imposing body forces at the site of interest and then storing the reciprocal Green's functions along arbitrary finite-fault surfaces. By using reciprocal Green's functions, we can then simulate many source scenarios for those faults because the primary numerical calculations need be done only once. The advantage of the proposed method is shown by evaluation of the site and path effects for three sites in the vicinity of the Los Angeles basin using the Southern California Velocity Model (version 2.2). In this study, we have simulated 300 realistic source scenarios for 5 major southern California faults and compared their responses at three sites. The effects of hypocenter location, the rupture speed, and slip function are tested in the scenarios. The results indicate that the variations in the peak velocity amplitudes and durations due to various source scenarios are as large as variations due to the heterogeneous velocity model.