Highly Accurate 3D Traveltime Calculation and Raytracing Based on Multi-stencils Fast Marching Method

Highly accurate seismic traveltime calculation and ray tracing methods have continuously been the key technique in fist arrival traveltime tomography. Classical fast marching method (FMM) only use one stencil to solve for the eikonal equation thus often suffer severe numerical error along diagonal directions. In this paper, we propose an improved version of 3D fast marching method (FMM), which is called 3D multi-stencils fast marching method (MSFM). In contrast, the new method computes the solution at each grid point along six different stencils rather than one, by which could covers the entire 26-neighbors of calculating point. Besides, The implementation scheme of MSFM for irregularly topography is also illustrated. Moreover, on the basis of MSFM, we put forward an accurate and efficient ray tracing algorithm based on tri-linear interpolation and Runge-Kutta method. Numerical experiments on synthetic complex near-surface model have verified the better accuracy of MSFM in contrast to FMM.