复杂地表条件下基于线性插值和窄带技术的地震波走时计算

摘要

为了在复杂地表条件下实现地震波走时计算,提出了一种基于线性插值和窄带技术的走时计算新方法.其中,线性插值用于局部走时计算,窄带技术用于局部波前捕获和追踪.为了逼近起伏地表,采用三角网和矩形网相结合的方法对速度模型进行剖分.为了得到局部走时计算公式,利用费马(Fermat)原理和关于入射点位置的限定条件.有关编程实践和数值试验表明:新方法不仅可以有效、灵活地处理地表高程的剧烈变化,而且还具有很好的适应性和稳定性,得到的计算结果满足波前传播规律.%For realizing the seismic traveltime computation under complex topographical conditions,we present a new method based on linear interpolation and narrow band technique.Here,the linear interpolation technique is used for carrying out the local traveltime computation,and the narrow band technique is used for capturing and propagating the wavefront.For fitting the complex topography,we use a hybrid grid,consisting of a triangular grid and a rectangular one,for dividing the velocity model into grid.For obtaining a formula for the local traveltime computation,we invoke the Fermat principle and a condition for limiting the position of the incident point.Programming practice and numerical tests show that the new method not only can treat the strong topographical change with effectiveness and flexibility,but also have satisfactory stability and adaptability to the complex velocity model.The results given by the new method consist with the laws on wave propagation.