宏观地震忽略吸收确定震源深度问题的通解及其精确度

ON THE GENERAL SOLUTION TO THE PROBLEMNEGLECTING ABSORBTION FOR THE DETERMINATIONOF EARTHQUAKE FOCAL DEPTH FROM MACROSEISMICDATA AND ITS PRECISION

分析G-R-闵公式后得出,它是从点源幅射场导出的,与地震宏观场不相应。因在近场震源不能视作点源。在分析过程中,导出相当于点源、线源或面源以及复杂源的幅射场的深度公式。对实际的地震,它的源类型一无所知,所以不预作假定,将源指标几何扩散率n作为待定参数,导出了一个物理意义明确而又普遍化的震源深度公式。此公式的诸解法中,以计算方法准确、精度高,作图法有直观的优点,但准确性差、精度低,图算法只作获取粗略值和考察数据均匀性用。计算了9个8级以上巨震、1个71/2大震,和两个M_L=3的有感地震的震源深度,经对比结果很好,利用计算得出震源类型,结合宏观场研究了这些地震的震源几何学。并且首次在国际上给出宏观地震震源深度值的标准误差。

Analysing the G-R-Min formula for hypocentral depth:in which I0 is the earthquake intensity at epicenter, Ii the intensity at the observational point i, and ri the radius of the isoseismals defined by Ii, it is conclued that derived from the radiant field of a point source the formula is unsuitable to the macroscismic field. In the analysing process, the formulas for the hypocentral depth corresponding to the point, linear or plane sources and more comp lex sources from their radiant fields have been derived.Furthermore, supposed that the indes of geometrical diffusivit y. within the macroseismie field is a variable parameter when n=2 corresponds to a point source and n= 1 the linear and plane sources, a universal formula for hypocentral depth might be derived as follows.in which the definitions of I0, Ii, ri and n are as those mentioned above. The results obtained by the formula are comparable with the available data. Finally, the value of inacroseismie hypocentral depth to a standard error has been first presented in the world.