Seismic wave modeling in tilted transversely isotropic medium with irregular topography by a mimetic finite-difference method on curvilinear staggered grids

Modeling of seismic wave propagation in tilted transversely isotropic medium with irregular topography has been considered as a difficult task for the finite-difference method. Currently, the most popular standard staggered grid scheme requires a rectilinear grid and poses restrictions on the anisotropic medium. To address this problem, we propose a new finite-difference method for simulating anisotropic wavefield propagation in the presence of strong topography. This method employs generalized curvilinear grids that conform to surface topography to discretize the computational domain, thereby eliminating staircase approximation artifacts associated with arbitrarily irregular surfaces. Additionally, we describe the implementation of a fully staggered grid (FSG) finite-difference scheme to solve the first-order hyperbolic velocity-stress equations on the curvilinear grid. The free-surface boundary conditions are accurately applied by a mimetic approach, which allows for a less restrictive grid spacing criterion in computations. Numerical tests verify that using the curvilinear grid, the FSG scheme and the mimetic finite-difference scheme can simulate seismic wave propagation in the presence of surface topography with sufficient accuracy. The present study focuses on the 2-D P-SV problem, though it can be extended to address 3-D P-SV problem in the future.