A Nonbalanced Staggered-Grid FDTD Scheme for the First-Order Elastic-Wave Extrapolation and Reverse-Time Migration

Abstract

In this study, an efficient and accurate staggered-grid finite-difference time-domain (SG-FDTD) method to solve the two-dimensional first-order stress-velocity elastic wave equation is proposed. In the conventional implementation of the SGFD method, the same SGFD operator is used to approximate the spatial derivatives. However, we propose a numerical method based on mixed SGFD operators which are more efficient but similar in accuracy when compared to a uniform SGFD operator. We refer to the proposed method as the non-balanced SGFD numerical scheme which combines high-order SGFD operators with second-order SGFD operators. The suitability of the proposed scheme is verified by dispersion analysis. Through SGFD modeling and reverse time migration examples, we demonstrate that the proposed non-balanced scheme offers a similar level of accuracy with a lower computation cost compared to the time-consuming conventional SGFD method.