【摘要】 本文用Delta矩阵的分离形式,对波场基本传播项进行重新组合,简化了利用(?)、(?)振幅比资料测定小震震源参数的计算程序。 利用本文的算法,对北京台网1980年2月至1982年12月所记录的47个小震震源参数进行了测定,其结果呈不规则分布。但平均结果与据初动符号得到的大震震源机制解接近。结果还表明,该时期北京地区的小震震源机制多数是走滑型断裂,P轴和T轴大多近于水平,且分别集中在北东—南西和北西—南东方向上。更多还原

【Abstract】 When we determine source parameters of small earthquakes by means of P and S amplitude ratios in the regional network, a key link of present algorithm is to compute coefficients of generalized transmission of the medium layer above a source in the network. In this paper, Delta matrics in separation form is recomposed by basic profagation terms of wave field, therefore a simpler computation process is obtained.We computed 47 small earthquakes recorded bv Beijing network from Feb. 1980 to Dec. 1982 on our improved algorithm. The results are irregular distribution. However, the average result is closed to source mechanism of the macroquake by means of first motion direction in this region. The results can be summarized as follows: Focal mechanisms of most small earthquakes during the period appear to be of the strike-slip fault, their pressional principal stresses P and tensile stresses T are most nearly horizontal, P axes and T axes concentrate on NE-SW and NW-SE respectively.更多还原