A New Second Order Absorbing Boundary Layer Formulation for Anisotropic-Elastic Wavefield Simulation

Abstract

The hybrid perfectly matched layer (H-PML) approach to boundary absorption, a combination of convolutional and multiaxial perfectly matched layer (C-PML and M-PML) approaches, is extended to simulate second-order displacement-stress elastic wave equations. The displacement components instead of the velocity components can be directly updated, which can further be used in elastic full waveform inversion. A general stability condition for the second-order displacement-stress elastic wave equations is also proposed. The C-PML and H-PML simulation that results in isotropic and anisotropic media are compared. H-PML is capable of absorbing boundary reflections in both isotropic and anisotropic media, but C-PML suffers severely from the boundary reflections in anisotropic media. The H-PML simulation results for both first- and second-order elastic wave equations show its efficiency in boundary reflections suppression. The computational cost comparison between C-PML and H-PML also demonstrated that H-PML needs smaller computational volumes than C-PML for suppressing the same level of boundary reflections, which is more suitably applied in anisotropic full waveform inversion to reduce the computational volume.