新源、和静交界ML6.8地震序列的应力降和震源机制研究  

Research on stress drops and the focal mechanisms of the Xinyuan-Hejing M_L6.8 earthquake sequences

作　　者：刘建明[1] 王琼[1] 刘杰[2] 邓菲[3] 向元[1] 杨文[1] 李金[1] 

机构地区：[1]新疆维吾尔自治区地震局乌鲁木市北京南路42号,830000 [2]中国地震台网中心,北京100045 [3]云南省地震局,昆明650224

出　　处：《中国地震》2016年第1期28-39,共12页Earthquake Research in China

基　　金：2014年度震情跟踪合同制定向工作任务(2014020110);新疆地震局科学基金(201402)联合资助

摘　　要：采用新疆区域台网记录的2012年6月30日新源、和静交界M_L6.8地震序列的数字波形资料,研究分析了余震序列应力降的变化特征及其地震序列震源机制的相关性。采用波谱分析方法和Brune震源模型,计算了新源、和静交界M_L6.8地震序列震源参数、地震序列中不同事件在相同台站的体波零频震源谱值、地震谱振幅相关系数;并对地震序列震源机制解进行聚类分组。结果表明:①在余震序列平静阶段,应力降呈平稳态势,强余震前应力降出现升高-回落变化过程;②滑动平均谱振幅相关系数在主震后发散,表明余震的震源机制解与主震的相关性降低;③震源机制解聚类分组结果显示,M_L6.8地震序列主要以走滑型地震为主,主压应力轴呈近NS向,与近NS向的构造应力场结果基本一致,一定程度上显示了地震前天山中段受NS向水平挤压应力作用明显;④震级、震源机制演化表明,强余震前震源机制解表现较好的一致性,显示了区域应力场控制作用增强,对后续强余震发生具有预测意义。Based on the digital waveform data recorded by Xinjiang Digital Seismic Network for the Xinyuan-Hejing ML6.8 earthquake sequences of June 30,2012,the paper analyzes stress drops of earthquake sequences and the correlation coefficients of focal mechanisms significant for strong aftershocks. Firstly,the source parameters of the Xinyuan-Hejing ML6.8 earthquake sequences are obtained by applying the spectrum analysis and the Brune＇s source model. Then,the correlation coefficients of spectral amplitude are calculated using the low-frequency spectral amplitude recorded by the same station for the different events. Finally,based on the results of the correlation coefficients of spectral amplitude,the events with similar focal mechanism are grouped using clustering method. The results show that：（1） The stress drop values show a steady trend in the aftershocks sequence calm period and the stress drop values show rise-fall in the strong aftershocks.（2） Moving average correlation coefficient of amplitude spectrum begins to spread after the main shock. It shows that the correlation decreases between the main shock and the aftershocks in mechanisms.（3） The results of focal mechanism groups show that the earthquake sequences are mainly strike slips. The stress distribution of the main pressure axis is nearly NS which is the same with the structural stress field.（4） The magnitude and mechanism show that there is an agreement before the strong aftershock,which shows that the regional stress field is enhanced.

关 键 词：新源、和静交界ML6.8地震序列 应力降 震源机制相关系数 体波谱振幅 聚类分组 

分 类 号：P315[天文地球—地震学]