岫岩5.4级地震序列主应力变化特征研究

Study on stress variation characteristics of Xiuyan 5.4 earthquake series

根据1999年岫岩地震序列的活动特点,将其划分为前震、余震密集、余震平静、余震衰减4个时段,利用收集整理的1999年6月至2000年9月间该序列中161次2.5级以上地震的震源机制解和Gephart的应力反演方法,研究了震源区各时段内构造应力场的总体特征和时序变化特征。结果表明,序列的主压应力方向与华北地区的构造应力场基本一致,而且最大主压应力的空间取向经历了主震前相对稳定—主震后分散—最大余震前相对稳定—最大余震后分散的全过程。该结果对主震和最大余震的预测具有一定的参考价值。

Based on the active characteristics of 1999 Xiuyan earthquake series, it is divided into four periods, namely, foreshock, aftershock concentration, aftershock tranquilization and aftershock attenuation. We used 161 focal mechanisms of M2.5 from June of 1999 to September of 2000 and stress inversion method by Gephart to study the overall characteristics and time series variation characteristics of tectonic stress field in every period of source area. It is found that the direction of the principal compressional stress is basically consistent with the direction of tectonic stress field in North China, and the spatial orientation of the maximum principal compressional stress experienced relative stabilization before the mainshock-disperse after the main shock-relative stabilization before the maximum aftershock-disperse after the maximum aftershock. This result has a certain reference value for forecasting of main shock and the maximum aftershock.