We performed numerical simulation for seismic waves propagation from the Mexican Pacific to Mexico basin. We improved the 2-D elastic code developed by a previous study based on the finite difference method including the radiation pattern for a point shear dislocation of arbitrary orientation The anelastic attenuation effects were incorporated using a time domain attenuation operator and the nonreflecting boundary conditions were included. To approximate the line source solution obtained by the 2-D method to 3-D source solution we mapped the seismograms using a correction filter for the difference in the pulse shape between the line and the point source solution. Finally, we matched synthetic seismograms with the observed data using the convolution of the source function. All this process allowed us to follow the 2.5-D method and obtain a code for a staggered-grid formulation with a few computational requirements for a current personal computer.
In order to compare results of our code, we used two scenarios and two models based on gravity and seismic data from previous studies. Both models were similar in the upper mantle and crust and different in the Trans-Mexican Volcanic Belt (TMVB) and basin. The first scenario was taken from the 2014 Papanoa, Guerrero, earthquake. The model for the basin and TMVB was constructed by isostatic compensation for this scenario. The second scenario was taken from the 2007 Guerrero earthquake. For this scenario we used a basin and TMVB structure derived from gravity data.
We found that the synthetic seismogrmas match well with the observed data when the distance between the 2-D model and station location was not large. Second scenario matched better than the first one when we used the velocity model with gravity information and distance between the line structure and a station was not large. This method and code can be applied to other basins and to active volcanos in future works.
Keywords: Seismic Modelling, Wave Propagation, 2.5-D Method