Effect of Grid Step Sizes on Computational Time Using Finite-Difference Method for Seismic Wave Modeling

摘要

Finite-difference method, a popular seismic forward modeling method is a technique which allows us to numerically solve partial differential equations like the wave equation solved in this paper. Beyond its use in standard data acquisition, it is a very instructive tool to understand how waves propagate in the earth's subsurface. Since the accuracy obtainable by using the finite difference scheme lies solely on its stability and ability to handle grid dispersion, this is achievable by applying appropriate grid step sizes. The developed finite-difference method was employed to generate snapshots of synthetic seismograms to highlight the effect of grid step sizes on computational time while ensuring numerical stability of the scheme used through accurate discretization of the medium and adopting Perfectly Matched Layer (PML) absorbing boundary conditions. Results shows that for a grid size of 5m × 5m × 5m having 260 × 260 × 100 grid points and time step of 100 - 500, the wavefield propagating is horizontally symmetric. From the results, the importance of grid step sizes on computational time is re-emphasized.