用广义射线和有限差分计算近场理论地震图的混合方法

本文提出一种结合广义射线和有限差分理论而形成的混合方法（以下简称混合方法）．在介质均匀区（包括平行介质分层区）应用广义射线理论，在介质不均匀区应用有限差分理论．在这种结合过程中，把均匀区广义射线的结果作为不均匀区有限差分区波场连续的输入．对于均匀介质模型，混合方法理论地震图和广义射线理论地震图、广义反射透射系数矩阵及离散波数法地震图的对比，取得了满意的结果，在数值上证明了该方法的正确性．计算了１９９０年８月５日Ｈａｋｏｎｅ地震前震在日本Ａｓｈｉｇａｒａ山谷盲测点的响应，理论地震图和实际资料的比较同样取得好的结果．这种方法可用于地震勘探、工程地震、强地面运动的研究．

THEORY AND APPLICATION OF HYBRID METHOD SEISMOGRAMS

A hybrid method combining finite-difference method and generalized ray theory is presented.This method is a combination of finite-difference method applied to heterogeneous region and generalized ray theory outside.This combination is an alternative to the use of generalized ray theory line solution as a source for finitedifference.In the case of a homogeneous region and a homogeneous overburden,synthetic seismograms computing by hybrid method are checked by the computing by generalized ray theory and generalized reflection-transmission coefficient matrlix and discrete wavenumber method.As the application of hybrid method,we simulate the strong motion of August 5,1990 Hakone foreshock in the blind sizes in Ashigara Valley,Japan.The. comparison. of the hybrid seismograms with the records, of Hakone foreshock yields a good result. Since the model size can be strongly enlarged and the computing time extremely reduced in comparison with usual finitedifference computations, the method can be expected to have a wide range of applications in seismic prospecting, earthquake engineering and strong motion seismology.