A discrete representation of material heterogeneity for the finite-difference modelling of seismic wave propagation in a poroelastic medium

As recently demonstrated the most advanced finite-difference (FD) schemes are sufficiently efficient and accurate numerical-modelling tools for seismic wave propagation and earthquake ground motion especially in local surface sedimentary structures. The key advantages of the explicit FD schemes are a uniform grid, no matter what positions of material interfaces are in the grid, and one scheme for all interior points, no matter what their positions are with respect to the material interfaces. Efficiency and accuracy is determined by the grid dispersion and discrete representation of a material heterogeneity. After having developed discrete representations for the elastic and viscoelastic media, we present here a new discrete representation of material heterogeneity in the poroelastic medium. The representation is capable of subcell resolution and makes it possible to model an arbitrary shape and position of an interface in the grid. At the same time, the structure and thus the number of operations in the FD scheme are unchanged compared to the homogeneous or smoothly heterogeneous medium.