大同晚期强余震前震源机制解的一致性特征  

COHERENCE CHARACTERISTICS OF FOCAL MECHANISM SOLUTIONS OF LATER-PERIOD STRONG AF TERSHOCKS

作　　者：刁桂苓[1] 赵英萍[1] 啜永清[2] 王勤彩[1] 高景春[1] 曹肃朝[1] 王焱[2] 朱振兴[1] 

机构地区：[1]河北省地震局,河北石家庄050021 [2]山西省地震局,山西太原030002

出　　处：《内陆地震》2004年第3期202-206,共5页Inland Earthquake

基　　金：国家科技攻关项目(2001BA601B01-01-05)资助.

摘　　要：取层状介质中一点源位错模型,由计算综合地震图得到P、S各自最大振幅,通过其最大振幅比值与观测资料拟合的方式来确定震源机制。大同遥测地震台网较好地记录了大同地震序列的大量小震。经系统地查阅台网和周围其他台站1990—2002年的全部记录,读取垂直向的P、S最大振幅数据,反演计算得到620个小地震的震源机制解。这些解的优势取向和华北构造应力场的方向相同。定义各个震源机制解的P、N、T轴和构造应力场的3个应力主轴在3维空间的夹角之和为一致性参数,发现在1991年和1999年发生的晚期强余震前2—8个月,一致性参数出现显著的下降。我们认为,这是具有短期预测意义的现象。According to point source dislocation modal in a layer medium, we calculated synthesis seismogram, obtained the maximum amplitudes of, and determined the focal mechanism by fitting the ratios of the maximum amplitudes and observation data. Datong telemetered seismic network has recorded a great amount of small shocks of earthquake series occurred in Dadong, Shanxi. We examined all the records in the network and its peripherial stations from 1990 to 2002, measured the maximum amplitudes of, and made an inverse calculation of the focal mechanism solutions of 620 small events. The predominant tropism of these solutions is the same as the direction of tectonic stress field in North China. We defined the sum of the inclinations of 3 principal stress axes in 3D coordinate system as coherence parameter, found the parameter had obvious drop 2—8 months before the later period strong aftershocks that occurred in 1991 and 1998. We think this is a phenomenon with short-term prediction significance.

关 键 词：震源机制解 一致性参数 强余震短期预测 

分 类 号：P315.72[天文地球—地震学]