2008年盈江地震序列的震源参数和震源机制相关系数研究  

Source Parameters and Correlation Coefficients of Focal Mechanisms for the 2008 Yingjiang Earthquake Sequence

作　　者：邓菲[1] 刘杰[2] 

机构地区：[1]中国地震局地震预测研究所,北京100036 [2]中国地震台网中心,北京100045

出　　处：《地震》2014年第2期22-34,共13页Earthquake

基　　金："十二五"国家科技支撑计划项目(2012BAK19B02)

摘　　要：基于云南数字地震台网记录的2008年盈江地震序列的数字波形资料,采用波谱分析方法和Brune震源模型,得到盈江地震序列的震源参数。利用两次地震事件的相同台站的震源谱参数(零频振幅)计算谱振幅相关系数,据此对地震的震源机制进行聚类分组,并收集和对比地震序列已知的震源机制解结果,发现每组内震源机制解P轴的相关性较好,且相关系数越大,P轴的方位角就越接近。将盈江地区划分为三个研究区,联合震源参数的应力降和聚类分组中每组的平均震源机制解结果研究地震序列发生过程中应力的释放水平和应力场方向变化特征。结果表明:不同阶段震源机制解类型的变化和转化特征一定程度上反映了孕震过程中区域应力场随时间的变化特征,并且地震震源机制解类型在时间段上的集中并向区域构造应力场方向转换的现象可能是发生强震的标志。震源机制解分组类型和对应类型的地震的应力降有一定依赖关系,震源机制解类型反映的应力场与区域应力场接近的地震应力降高,震源机制解类型反映的应力场与区域应力场差距较大的地震应力降普遍较低。Based on the digital waveform data recorded by the Yunnan Digital Seismic Net- work in 2008, the source parameters of the 2008 Yingjiang earthquake sequence are ob- tained by applying spectrum analysis and the Brunets source model. The correlation coeffi- cients are calculated using the low-frequency spectral amplitude recorded by the same sta- tion for 2 events, and the events with similar focal mechanism can be grouped using cluste- ring method. Comparing with the obtained focal mechanisms, it is found that there are good relations in the trend of P axes in each group and if there are higher correlation coeffi- cients, the trend of P axes are closer. The Yingjiang area is divided into 3 studied regions to analyze the stress levels and stress directions by combining the source parameters and the mean focal mechanism of each group. The results show that the change and transfor mation of types of focal mechanism solutions at different stages reflects the temporal char- acteristics of the regional stress field, and that a type of earthquake focal mechanism solu- tions concentrated in a time period and switching to regional stress field may be a sign of strong earthquakes. There is some relationship between the stress drop and the type of fo- cal mechanism. The closer the direction of the focal mechanism in a group close to the re- gion stress field, the higher the stress drops increase.

关 键 词：应力降 震源机制相关性 聚类分组 2008年盈江地震序列 

分 类 号：P315.7[天文地球—地震学]