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Title:: The Temporal-Spatial Pattern of Focal Mechanism Consistency of Small Earthquake Sequence in Lushan

作者:: 段云歌¹; 陈天长¹; 苏金蓉¹; 雷建设²; 唐淋¹; 吴朋¹; (1.四川省地震局,四川成都 610041; 2.中国地震局地壳应力研究所,北京 100085)

Author(s):: DUAN Yunge¹; CHEN Tianchang¹; SU Jinrong¹; LEI Jianshe²; TANG Lin¹; WU Peng¹; (1. Sichuan Earthquake Agency,Chengdu 610041,Sichuan,China,)(2. Institute of Crustal Dynamics,China Earthquake Administration,Beijing 100085,China)

Keywords:: Lushan 7.0 Earthquake; aftershock sequence; correlation coefficient of spectral amplitude; focal mechanism consistency

摘要:: 利用体波谱振幅相关系数分析方法,对2013年4月20日至6月30日芦山M_S7.0地震余震序列中四川地震台网固定台站记录的M_L2.0～4.0地震的震源机制一致性进行了研究。将主要研究区分为5个子区,分区计算震群的平均相关系数。结果显示,同一时段内,震后2区平均相关系数最高,达0.809,随着与该区距离的增大而逐渐减小。4区2013年6月平均相关系数最低,仅为0.524; 整个研究区的总平均相关系数由0.785变至0.575。主震发生后,随着时间的推移,各子区内地震的平均相关系数均逐渐减小; 随着区域应力场能量的释放,震群的震源机制一致性逐渐变差。

Abstract:: The method of spectral amplitude correlation is used to research the focal mechanism consistency of aftershocks from M_L2.0 to M_L4.0 of Lushan M_S7.0,which from 20th April to 30th June,2013. 5 subareas are set up for the research. The average correlation coefficient are calculate in each subarea,using the digital waveform records from permanent stations in Sichuan network. The result shows that the average correlation coefficient is highest in sub 2 just after the main earthquake,which reached 0.809,and the lowest one is 0.524 in sub 4 in June. The average correlation coefficient in the whole area reduced from 0.785 to 0.575. It is indicate that the average correlation coefficient in each subarea decreased as time goes by. It is highest in sub 2 in same period of time,and which decreased with the distance to the subarea. This shows that,the focal mechanism consistency of aftershocks gradually getting worse with the release of the regional stress field energy after main earthquake,and the focal mechanism become more disordered.