2014年5月云南盈江M_S6.1地震序列横波分裂讨论  

Shear Wave Splitting Analysis of the 2014 Yingjiang M_S6.1 Earthquake Sequence,Yunnan

作　　者：吴朋[1] 秦敏[2] 赵翠萍[3] 苏金蓉[1] 华卫[3] 王宇航[1] WU Peng;QIN Min;ZHAO Cui-Ping;SU Jin-Rong;HUA Wei;WANG Yu-Hang(Earthquake Administration of Siehuan Province,Chengdu 610041,China;Earthquake Administration of Yunnan Province,Kunming 650224,China;Institute of Earthquake Science,CEA,Beijing 1O003g,China)

机构地区：[1]四川省地震局,四川成都610041 [2]云南省地震局,云南昆明650224 [3]中国地震局地震预测研究所,北京100036

出　　处：《地震》2018年第4期172-180,共9页Earthquake

基　　金：中国地震局测震台网青年骨干培养专项(20160522和20160521);2017年中国地震局台站三结合课题(CEA-JC/3JH-162504)

摘　　要：2014年5月24日、30日云南盈江地区先后发生了M_S5.6和M_S6.1地震。采用质点运动判别与偏振分析相结合的方法测定了此次地震序列横波分裂参数,即快波偏振方向和慢波延迟时间,最后获得了4个台站的横波分裂参数。震源区附近的两个台站KAC、MNO快波偏振优势方向为NS向,与区域主压应力轴方向一致。在M_S6.1地震发生后MNO台站快波偏振方向出现了紊乱现象,KAC台站快波偏振方向发生了偏转。这4个台站的平均慢波延迟时间分布在1.50～4.47ms/km。靠近主震附近的KAC和MNO台的平均延迟时间均大于4.0ms/km,表明距主震越近各向异性的程度越大。MNO台站在M_S6.1地震前慢波延迟时间的突然减小意味着临近主震前震源区地壳应力释放。The Ms5.6 and 6.1 earthquakes occurred on May 24th and 30th, 2014 in Yingiiang area, Yunnan Province, respectively. We measured the shear wave splitting parameters： the polarization direction of fast shear wave and the delay time of slow shear wave of the Yingjiang earthquake sequence by the combined method of the particle motion discrimination and the polarization analysis. Finally,we obtained the shear waves splitting parameters at 4 seismic stations. The results show the dominant polarization direction of fast shear wave is NS at stations KAC and MNO around the focal region, which is in a greement with the direction of the regional principal compressive stress. The polarization direction of fast shear wave at station MNO became in disorder and that of KAC deflected after the Ms6.1 earthquake. The average delay time of slow shear wave at the 4 stations is in the range of 1.50～4.47 ms/km. The average delay time is greater than 4.0 ms/km at stations KAC and MNO near the mainshock, which suggests the closer to the mainshock, the greater the degree of anisotropy. The delay time of slow shear wave reduced suddenly at station MNO before the Ms6.1 earthquake, implying the crustal stress released in the focal region before the mainshock.

关 键 词：横波分裂 快横波偏振方向 慢波延迟时间 2014年盈江Ms4.6地震 

分 类 号：P315.7[天文地球—地震学]