2D time-domain acoustic-elastic coupled modeling: a cell-based finite-difference method

Abstract

To describe wave propagation in a fluid-solid environment which is usually encountered during marine seismic exploration, we design a time-domain acoustic-elastic coupled modeling algorithm based on the cell-based finite-difference method. The cellbased method has proven to delineate stress-free conditions correctly at the free surface with just changes in the material properties, which indicates that it can also properly deal with subsurface interface boundaries. In the acoustic-elastic coupled modeling, we first compose finite differences individually for the acoustic and elastic media; we then combine the differences using fluid-solid interface boundary conditions. Numerical experiments show that the cell-based coupled modeling algorithm gives solutions compatible with analytic solutions and that it properly describes S- and converted waves as well as P-waves. Applying the cell-based coupled modeling algorithm to a slope model, we confirm that our coupled modeling algorithm describes irregular interfaces properly, although it employs a staircase approximation of them.