射线层析技术中的算法探讨

ON ALGORITHMS OF RAY-PATH TOMOGRAPHY

成都地质学院深部研究所

Deep Geology Research Institute, Chengdu College of Geosciences

本文首先讨论了目前常见的弯曲射线层析方法中所存在的问题。其次,以网格节点局部线性函数描述的二维介质模型为基础,给出了一种精度较高的地震波走时层析成象的计算公式。其特点是(1)采用局部坐标的旋转和平移变换,简化了射线追踪中射线坐标的求解和反演中的部分计算过程;(2)导出了解析的雅可比矩阵的计算公式,与N·D Bregman等人给出的公式相比,较为简单。

In this paper, problems commonly existing in the curved raypath tomography were examined and analysed before everything. Based on the 2-D model characterized by mesh node local linear function,an algorithm for seismic travel time tomography with high accuracy was given. Such an algorithm is characterized by; (1 )By rotating and translating the local coordinates,the extraction of the coordinates of ray-path and part of the procedure of inversion calculation could be simplified) (2)By means of the algorithm recommended, the analytical formula for calculating the Jacobin matrix was derived and it is simpler than that derived by N. D. Bregman,et al.