τ法反演与地壳结构研究

本文对用爆炸地震资料研究地壳与上地幔结构及速度分布的τ法反演进行了探讨,并且在Bessonova提出的平均值方法的基础上,就减少解的不确定性及简化反演过程提出了新的作法:1.τ（p）的上下界各自独立地参与反演而后再将所得到的结果合并起来;2.在τ法反演中,抽去地壳模型中的低速层。根据以上两种计算方案,改进方法,取得较好的效果。 本文还用Bessonova的平均值方法计算了我国东部地区地壳-上地幔爆炸地震探测剖面的实例。该地区地壳厚度约为31 km,在18 km深处存在着低速层,厚度约6 km,速度为6 km/s。

THE TAU METHOD INVERSION AND THE CRUST STRUCTURE RESEARCH

In order to obtain the structure and the velocity distribution in the crust and upper mantle, the tau method which is widely used in explosion seimology is studied in this paper. Based on Bessonova.'s method （1974）, some improvements for minimizing the uncertainty of solution and simplifying the inversion procedure are presented.1. The inversions of the upper and lower boundaries of τ（p） are carried out and after that the previous results are summed up.2. The effect of low velocity layers can be subtracted from the initial model in the tau method.The application of above approaches has led to fairly satisfactory results.Bessonova's method is applied to deep seismic sounding data of the Bast China. The results indicate that the crustal thickness in this region is about 31 km; there exists a low-velocity layer of 6 km thick （Vp=6 km/sec） at the depth of 18 km.