分块三维速度模型生成及理论地震图的计算

BLOCK-LIKE 3-D VELOCITY MODELS AND SYNTHETIC BODY WAVE SEISMOGRAMS

本文提出了在计算机上实现分块三维地壳模型及利用加权最小二乘拟合生成平缓光滑的三维速度函数的方法,给出了适用于分块、块内速度连续变化的三维模型中Cauchy射线追踪的新算法,简介了基于上述方法反射线的基本理论所编制的合成三维理论地震图的程序包RSSGTD.给出的两个盆地状模型的算例表明,所使用的模型生成方法具有模拟复杂地壳结构的能力;与三维样条函数方法比较,最小二乘拟合方法能给出更加适合射线方法合成地震图计算的速度函数,并且内存小、计算速度快;所给出的Cauchy射线追踪算法能够适合块状模型中任何体波射线的追踪.

Methods for generating block-like 3-D crust models and velocity functions with upto two degree patial derivatives from discrete samples are introduced in this paper. An algorithm used for tracing the complex ray fields in the block-like models is presented. By using these new methods and the asymptotic ray theory, the package RSSGTD is designed to compute body wave fields in the block-like 3-D models. For test purpose,two basin-like models are used to calculate synthetic seismograms. The results show that our methods are capable of generating complex crust models and the algorithm is suitable for tracing rays in the block-like models.