由大量的地震资料推断的我国大陆构造应力场

THE TECTONIC STRESS FIELD OF CHINESE CONTINENT DEDUCED FROM A GREAT NUMBER OF EARTHQUAKES

利用多个小地震的P波初动方向数据推断了新疆和西藏部分地区主应力轴的方向.根据以前华北、东部大陆和西南地区的工作结果,对个别地区补充新数据后重新作了分析;加上本文关于新疆和西藏地区的新结果,编制了我国大陆的地震构造应力场方向图.利用Brillinger等的概率模型,估计了用多个地震P波初动方向推断平均P、T轴的误差.讨论了单个大地震震源机制解的P轴与所在地区平均P轴方位角的差异.总结了我国大陆地震构造应力场的主要特征.

The directions of mean principal stress axes in parts of Xinjiang and Xizang area are deduced from the polarity readings of P-wave first motion of a number of small earthquakes. Based on the results previously obtained for North China, the eastern and southeastern part of Chinese continent, after correcting the results for a few subrcgions in these areas with supplementary data, and adding the new results of this study for the Xinjiang and Xizang area, a map of the tectonic stress directions for Chinese continent is compiled.The uncertainties in deducing the mean P and T axes from P-wavc first motion polarity data of multiple earthquakes are estimated by applying the probability model proposed by Bril-linger et al. (1980). The deviation of the P axes of individual focal mechanism solutions for large earthquakes from the mean P axes of the corresponding subregions is analysed, and thought to be possibly related to the frictional angles of the faults. Finally, this study sums up the main feartures of the tectonic stress field for the Chinese continent.