3D frequency-domain elastic wave modeling using a fourth- and second-order combined staggered-grid finite-difference scheme

By combining the average-derivative method and the anti-lumped mass strategy, we develop a fourth- and second-order combined staggered-grid finite-difference (FSSFD) scheme for 3D elastic wave modeling. The dispersion analysis shows that this scheme has similar accuracy to the optimal fourth-order scheme and higher accuracy than the classical fourth-order scheme and the optimal and classical second-order schemes. When the phase velocity error limit is set to 1%, the new scheme requires only 3 grid points per unit shear wavelength. Finally, numerical experiments are performed to analyze the advantages of the new method in terms of accuracy and computational cost.