A Shortest-path-aided Fast-sweeping Method for the Acoustic VTI Eikonal Equation

Summary The accuracy of the traditional fast-sweeping method (FSM) is severely decreased in the diagonal directions (x=z and x=-z in two-dimensional cases) due to the source singularity and numerical errors in these ray directions. To improve the accuracy of travel time calculation in FSM, we propose a shortest-path-aided fast-sweeping method (SPAFSM) in isotropic cases ( Zhang et al., 2023 ). We extend the SPAFSM to the acoustic vertically transversely isotropic (VTI) media in this paper. This method is implemented nearly without additional computational cost and memory consumption. Numerical examples illustrate that the accuracy of travel time is mainly improved in the diagonal directions by the shortest-path-aided solution, hence, traveltime isochrons are closer to the wavefronts.