An improved acoustic/elastic interface approach for 2D staggered grid finite-difference modeling of Rayleigh waves in the presence of surface topography

Rayleigh waves are generated along the free-surface and their propagation can be strongly influenced by surface topography. Therefore, a critical aspect of Rayleigh-wave study is to understand the wave-propagation behavior in the presence of surface topography. The acoustic/elastic boundary approach was incorporated into a ‘stair-case’ mesh for Rayleigh-wave modeling in the presence of surface topography. The conventional acoustic/elastic boundary approach, however, fails to completely fulfill the free-surface boundary condition at some grid nodes, leading to unphysical simulation results. To solve this problem, we develop a stable acoustic/elastic boundary approach that fully satisfies the free-surface boundary condition by adjusting the free boundary conditions at problematic nodes in the mesh. The accuracy is demonstrated by modeling tests in two-dimensional isotropic models in the presence of surface topography. And compared to the improved vacuum formulation, the proposed method takes less time. Our approach optimizes the free-surface boundary condition and enables the high-precision numerical simulation of Rayleigh waves. •A stable acoustic/elastic boundary approach is developed to satisfy the free-surface boundary condition by adjusting problematic nodes.•The accuracy of the approach is demonstrated through modeling tests using two-dimensional isotropic models with surface topography.•The proposed approach is more efficient than the improved vacuum formulation, requiring less time.