震源区和接收区结构不同情况下体波合成地震图的矩阵-射线方法

THE RAY-MATRIX METHOD OF SYNTHETIC SEISMOGRAMS FOR DIFFERENT SOURCE AND RECEIVER STRUCTURES

本文进一步扩展了合成地震图的广义射线方法.由于算法中将地球模型划分成震源区、接收区和地幔区,因此可用于计算震源区与接收区速度结构不同时的体波合成地震图.新算法把广义射线理论与传播矩阵理论结合起来,并采用了分层Q值模型,从而可以自动包括指定介质层内所有多次波的混响.为简便数据准备,设计了射线编码自动生成算法. 本文算法与Kind扩展的反射率法用相同的地球模型进行了数值结果对比,结果表明,矩阵-射线方法用于计算体波地震图时,不但有足够好的精度,而且还具有速度快并适于单个震相研究的优点.在计算由10个接收点组成的地震剖面时,其计算时间仅为反射率法的7％左右.

The generalized ray theory of synthetic seismograms has been exfended to calculate seismic body waveforms in the Earth model with different source and receiver areas. For this purpose, the Earth model used is divided into three parts: the source, the receiver and the mantle areas. In the new algorithm, the generalized ray theory and the propagator-matrix theory are combined together, and the multiple reflections within thin layers can be included automatically. A new automatic ray-code technique has been described, which makes the data file for the ray-codes used greatly simplified.The algorithm in this paper has been compared with the reflectivity method (Kind, 1985) on the same model. It has been shown that the synthetic seismograms by this two methods are quite consistent each other and the computation time of our method is much less than that of the reflectivity method.