摘要
本文应用Pnl及SH波理论地震图方法求得了大同-阳高地震前、主、余震的震源机制解,并结合发震区的地质构造,推断了这次地震的发震过程及发震构造。结果表明:前、主、余震发生在同一断层上,前、主震发生在浅层,余震发生在深层;发震断层为一具有右旋走滑分量的正断层,走向201°,倾向NW,浅层倾角75°左右,深层倾角58°左右;前、主震断层运动主要为平移运动,滑动角为—169°,余震断层运动的平移与下滑分量几乎相等,滑动角为—138°。发震区的应力场为北60°东水平向挤压,与华北地区统一应力场一致,深部应力场的P轴俯角较大,体现了发震区局部应力场的特征,并与此区域较大的形变沉降相符合。由华北地区的地震活动性,我们还推测这次地震实际上是此区域的应力场沿桑干河断裂带释放能量的结果。此外,文中还讨论了这次地震与一般地堑地震的异同点。
In this paper,the focal mechanisms of the foreshock,mainshock and aftershock of the 1989 Da-tong-Yanggao earthquake were determined by Pnl and SH waveform fitting,and the earthquake progresses and seismotectonics were inferred. The results show that the foreshock, mainshock and aftershock occurred on the same fault;the fault motions were right-lateral strike slip with mechanism;strike 201°,shallow dip 75°,rake-169°,deep dip 58°,rake-138°;the epicentral area is subject to a NEE-SWW horizontal compression and a NNW-SSE extension which is consistent with the tectonic stress orientation of North China,and the relatively large P axis plunge in depth corresponded with the great depressed deformation in this area. In addition,the similarities and differences between the Datong-Yanggao earthquake and general graben-associated earthquake were discussed.
出处
《中国地震》
CSCD
北大核心
1992年第1期51-59,共9页
Earthquake Research in China
