论确定地震震源深度的地震宏观方法及其解答

ON THE METHOD FOR DETERMINATION OF EARTHQUAKE FOCAL DEPTH BASED ON THE MACROSEISMIC DATA AND ITS SOLUTIONS

摘要:

作者基于在近场震源不能视作点源的认识,分析导出了相当于线、面源幅射场的深度公式,进而对源的类型不予作假定,将源指标的几何扩散率n作为待定参数,导出了一个物理意义明确且普遍化的震源深度公式。该公式的诸种解法中,以计算方法较准确,精度高;作图求解有较直观的优点,但准确性差,精度低;图算法仅作为获取粗略值和考察数据的均匀性用。用该公式对我国发生的一些不同震级的地震的震源深度进行了计算,经对比,效果很好。利用计算所得震源类型,初步研究了这些地震的震源几何学,并且首次给出了宏观地震震源深度测定值的标准误差。

Abstract:

Based on a point of view that the near-field seismic source can't be considered as a point source, the author derived a formula for focal depth corresponding to the line and plane sources from their radiant field as follows:h=r₁√10(1₀-1_i)/(1.5m)-1
Where I₀ is the seismic intensity at epicentre, I₁, the intensity at observation point i, and r₁ the radius of the isoseismal curves defined by the intensity I₁, the index n of geometrical diffusivity within macroseismic field is a varible parameter. For n=2, it is G-R-Min formula, for n=1-2 corresponds to S=1.5-3.0 in Blake formula, n=1.78, Blake formula et al. And importantly, first gave the value of macroseismic focal depth to a standard error in the world.