摘要
叙述了利用P波初动和短周期体波振幅联合测定震源机制解和利用震源机制解求取区域主应力张量的方法,采用成都遥测数字地震台网在2001年2月雅江Ms 5.0、Ms 6.0地震前后的3.0级以上的26个地震,共14个台站的垂直分向速度波形记录进行计算。使用主事件定位法,确定了这些地震较准确的震中位置,并在此后的计算中采用该数据。震源机制解结果表明:5.0和6.0级地震与另外3次地震为走滑型,呈北东向分布;而外围的其他21次地震全部是倾滑型。分析认为,雅江震区位于鲜水河断裂带南端西侧的以贡嘎山为中心的地壳隆起区内,地壳的抬升运动导致震源体的形成,两种破裂方式与之有关。前震与余震时段的最大主压应力σ1轴的方向大致相同,5.0和6.0级地震期间,σ1轴的方向偏转了约100°。
The method of joint determination of focal mechanism solution and stress field using P wave polarities and short-period body wave amplitudas are presented, using 26 earthquakes (M≥3) of 2001 Yajiang Ms5. 0 and Ms6. 0 earthquake sequence with 14 vertical component velocity waveform records which are from Chengdu telemetry seismic network. More accu-rate epicenter location data were obtained by use of the master event technique for the follow-ing computation. The results show that the focal mechanism solutions of 5 earthquakes (in-cluding Ms5. 0 and Ms6. 0) are strike slip type; and others are dip slip type. The further a-nalysis indicate that 2 rupture ways were resulted from the formation of earthquake focus which is caused by earth crust uplift motion, since Yajiang earthquake area is located at the south-west side of Xianshuihe fault zone and within the crust uplift region which Gonggas-han mountain is considered to be the center. In addition, the direction of major principal stress axis are almost the same before and after the main shock, but the direction rotated a-bout 100° during Ms5. 0 and Ms6. 0's occurrences.
出处
《地震地磁观测与研究》
2004年第4期48-55,共8页
Seismological and Geomagnetic Observation and Research
基金
国家"十五"科技攻关项目<强地震短期预测技术研究>02-03-04课题资助
关键词
雅江6.0级地震
震源机制
应力场
Yajiang Ms6. 0 earthquake, focal mechanism, stress field
