Two-Dimensional Global Seismic-Wave Simulation Using Multiblock Structured Grid Finite-Difference Method

With increasing computational power, global seismic wavefield simulations have become feasible, with the spectral-element method (SEM) demonstrating outstanding performance. Despite these advances, extending other numerical methods to the global scale remains nontrivial. In particular, the traditional finite-difference method (FDM) encounters notable challenges in global-scale applications due to its limited grid flexibility. To address this issue, we propose a curvilinear grid FDM (CGFDM) tailored for 2D global seismic-wave modeling. The method integrates several key techniques: (1) the dispersion-relation–preserving optimized MacCormack operators on collocated grids to preserve dispersion and accuracy, (2) the traction-image method for free-surface boundary conditions, (3) the split-node technique for solid–fluid coupling, and (4) multiblock structured grids to overcome polar singularities and enable nonuniform meshing adapted to Earth’s heterogeneous structure. These innovations substantially enhance both the geometric adaptability and numerical stability of FDM for global-scale problems. This article presents the theoretical formulation and numerical implementation of CGFDM, introduces a multiblock mesh design suitable for global simulations, and verifies the method against the SEM benchmark. The results demonstrate that CGFDM achieves high accuracy and computational efficiency, establishing it as a robust and promising alternative for large-scale seismic wavefield modeling.