山西大同-阳高M>5.5地震震源机制中心解的确定

Determination of Focal Mechanism Central Solution of Datong Yanggao M>5.5 Earthquake in Shanxi Province

1989年大同-阳高6.1级地震是山西地区自现代仪器记录以来最显著的地震事件,之后该地又发生多次中强地震,这些地震的发生受到诸多地震学者的关注。不同研究机构和多位学者应用不同方法和资料,求得这些中强地震的震源机制解,同一个地震的多个解间存在一定的差别。文章采用最小空间旋转角表达2个震源机制解的差别,然后从已知多个震源机制中确定中心解,使其与所有收集的震源机制解差别的平方和最小。研究结果可为后续地壳应力场、地震应力触发、地震概率预测、地震动力学等分析研究工作提供合理选取震源机制解即中心解提供参考借鉴。

The Datong Yanggao 6.1 earthquake in 1989 is the most significant earthquake event in Shanxi since modern instrument records.After that,there have been many moderately strong earthquakes.The occurrence of these earthquakes has attracted the attention of many seismologists.Different research institutions and scholars use different methods and data to obtain the focal mechanism solutions of these moderately strong earthquakes.There are some differences in multiple solutions of the same earthquake.In this paper,the difference between the two focal mechanism solutions is expressed by the minimum spatial rotation angle,and then the central solution is determined from the known multiple focal mechanisms to minimize the sum of squares of the difference between the central solution and all the collected focal mechanism solutions.The research results will provide a reference for the subsequent analysis and research work of crustal stress field,seismic stress triggering,seismic probability prediction and seismic dynamics and so on to reasonably select the focal mechanism solution,that is,the central solution.