三维复杂山地多级次群推进迎风混合法多波型走时计算

Computation of multiple seismic traveltime in mountainous areas with complex 3D conditions using the multistage group marching upwind hybrid method

三维复杂山地条件下的各种地震波型的走时计算技术,可以直接用于复杂山地区域地震波运动学特性的分析、地震数据采集观测系统的设计以及直接基于三维复杂地表的地震数据处理技术的研发.为了在三维复杂地表条件下准确、灵活且稳定地计算各种地震波型的走时,提出一种多级次群推进迎风混合法.该算法利用不等距迎风差分法简洁稳定地处理三维复杂地表及附近的局部走时计算问题,利用计算精度不错的迎风双线性插值法处理绝大部分均匀正方体网格中的局部走时计算问题,利用群推进法模拟三维复杂地表条件下地震波前的扩展问题,利用多级次算法处理各种类型的地震波的走时计算问题.算法分析和计算实例表明:新方法具有很好的计算精度与效率,且能灵活稳定地处理三维复杂地表复杂介质条件下的多波型走时计算问题.

The techniques for computing traveltime of different types of seismic waves in mountainous areas with 3D complex topographic conditions can be directly used for analyzing the kinematical characteristics of seismic waves, designing the seismic data acquisition system, and developing some seismic data processing techniques directly for the 3D complex earth＇s surface. To compute traveltime of different types of seismic waves with high accuracy, great flexibility, and unconditional stability in 3D complex topographic conditions, we propose a multistage group marching upwind hybrid method. In this new method, we use the upwind finite-difference method with non-uniform grid spacing to compute the local seismic traveltime on or nearby the earth＇s surface with unconditional stability and concisely. The local seismic traveltime on the other uniform grids is computed by using the upwind bilinear interpolation method which has high accuracy. We also use the group marching method to simulate flexibly the extended processing of the seismic wave-front in 3D complex topographic conditions. Finally, the computational problem of multiple seismic traveltime is solved flexibly by the multistage algorithm. The contrast analysis to computational accuracy and the numerical example show that the new method presented in this paper has high accuracy and the flexible adaptability to solve the problem of multiple seismic traveltime computation in mountainous areas with complicated media and 3D complex surface topography.