安庆4.8级地震的余震S波分裂研究  

Study on Shear Wave Splitting of Aftershocks of M4.8 Anqing Earthquake

作　　者：李发[1] 李罡风[1] 张佑龙[1] 张学应[1] 朱生水[1] 裴红云[1] 赵希磊[1] 

机构地区：[1]安徽省地震局,安徽合肥230031

出　　处：《华南地震》2012年第1期28-34,共7页South China Journal of Seismology

基　　金：安徽省地震局科研基金(201109)资助

摘　　要：利用安徽数字地震台网安庆台记录的地震波形资料,运行Matlap S波分裂程序,对2011年1月19日安徽安庆4.8级地震的余震序列开展S波分裂研究。结果表明,快S波偏振方向有两个优势取向,分别为N73°E和N94°E,初步判断为区域应力场导致的EDA裂隙系各向异性结果。其中快S波N73°E偏振方向与区域应力场的主压应力方向N74°E基本相同,而快S波N94°E偏振方向稍有偏差,可能是由于4.8级主震产生的应力扰动引起的。慢S波延迟时间在0.82～10.92范围内变化,平均为2.84,主震后,延迟时间明显下降,可能反映了震后应力的释放过程,而几次较大余震前则处于上升高值状态,可能反映了较大余震前的应力积累过程。Using Anqing M4.8 earthquake sequence data recorded by Anqing station of Anhui Digital Seismic Network,by matlap shear wave splitting order,making shear wave splitting study on aftershocks sequence of M4.8 Anqing Earthquake on January 19 2011.The results show that there are two preferred polarization directions from the fast shear wave.N73°E and N94°E respectively,which were resulted from the anisotropy of the stress-induced cracks（EDA）.The polarization direction for the fast shear wave N73°E was in accord with principal compression stress axis N74°E of the source stress field.But the polarization direction for the fast shear wave N94°E was different,which may be due to the stress disturbance imposed by the M4.8 mainshock on regional background stress field.The time delay of shear wave splitting from 0.82ms/km to 10.92ms/km and the average of the whole process was 2.84ms/km.After mainshock,the time delay of shear wave splitting dropped apparently,which may reflect the release of the principal compression stress.The time delay of shear wave splitting rose with higher values of state before some larger aftershock,which may reflect the accumulation of the principal compression stress before shocks.

关 键 词：S波分裂 偏振方向 延迟时间 各向异性 安庆地震 

分 类 号：P315.925[天文地球—地震学]