Optimized Least Squares Method for Elastic-wave Variable-order Rotated Staggered-grid Forward Modeling

Forward modeling of seismic waves is an effective numerical simulation method to analyse geological structure changes in subsurface. In elastic wave forward modeling, the rotated staggered-grid method (RSM) is a modification of the standard staggered-grid method. The variable-order rotated staggered-grid method (VRSM) is further developed after applying the variable-order method to the RSM to solve the numerical dispersion problem of the RSM and reduce computing cost. In this study, the optimized least squares method (OLSM) is developed by combining the advantages of the least squares method (LSM) and the Taylor series expansion method (TSM). And we develop the optimized variable-order rotated staggered-grid method (OVRSM) by applying the OLSM to the VRSM, which can decrease the dispersion error and improve the precision of the VRSM. The theoretical deduction and experiments confirm the effectiveness of the OVRSM and its new order distribution, and demonstrate the potential of the OVRSM in high precision modeling.