2016年10月20日射阳M_S4.4地震的震源机制与地震序列的时空分布特征  

Focal mechanism of the Sheyang M_S4.4 earthquake on October 20,2016 and the spatio-temporal distribution of the earthquake sequence

作　　者：李锋[1] 李迎春[1] 李强[2] 冯志生[1] 王俊菲[1] 

机构地区：[1]江苏省地震局,中国南京210014 [2]福建省地震局,中国福州350003

出　　处：《地震学报》2017年第5期659-668,共10页Acta Seismologica Sinica

基　　金：江苏省自然科学基金(BK20131033);江苏省社会发展项目(BE2010751);中国地震局监测预报司震情跟踪定向工作任务(2016010124);江苏省地震局青年科学基金(201508QY)共同资助

摘　　要：基于江苏地区测震台网记录,采用CAP方法反演了2016年10月20日射阳M_S4.4地震的震源机制解和震源深度;利用HypoDD方法对射阳地震序列中M_L≥1.5地震进行了重新定位.结果显示:射阳M_S4.4地震的震源机制参数分别为节面Ⅰ:走向304°,倾角53°,滑动角0°;节面Ⅱ:走向214°,倾角90°,滑动角143°,震源深度约为14km.双差定位结果显示:此次射阳地震序列分布于洪泽—沟墩断裂与盐城—南洋岸断裂之间,在水平空间内,其震中分布的优势方向为NW60°,由SE向NW迁移;地震序列深度分布在6—23km范围内.根据所反演的震源机制参数和地震序列精定位结果,本文推测射阳M_S4.4地震的断层面解为震源机制解的节面Ⅰ,该地震可能是在区域背景应力场的作用下,沿NW向剪切破裂产生的左旋走滑地震事件.Based on the digital waveforms of Jiangsu seismic network,the focal mechanism of the Sheyang MS4.4 earthquake was determined by using the CAP（cut and paste）method,and the ML≥1.5 events of Sheyang earthquake sequence were relocated by using the HypoDD method.The result shows that the strike,dip and rake of the MS4.4 event are 304°,53°,0°for the nodal plane Ⅰ,and 214°,90°,143°for the nodal plane Ⅱ,respectively,and the centroid depth is about 14 km.The relocation for the Sheyang earthquake sequence shows that the earthquake sequence was located between Hongze-Goudun fault and Yancheng-Nanyang＇an fault with the predominant direction NW60°in horizontal space,and the sequence propagated from southeast to northwest with the focal depth of 6--23 km.According to the focal mechanism solutions and the relocation results,we deduce that the Sheyang MS4.4 earthquake is a left-lateral slip event induced by shear rupture northwestwards under regional stress field,and its fault plane is nodal plane Ⅰ.

关 键 词：射阳MS4.4地震 震源机制 双差定位 库伦-摩尔破裂准则 

分 类 号：P315.31[天文地球—地震学]