2014年川滇交界东段鲁甸M_S 6.5地震序列重新定位及发震构造分析  

Relocation of Ludian M_S 6.5 earthquake sequence and analysis on its seismogenic structure in the region of the eastern Sichuan-Yunnan border

作　　者：李荪海[1] 颜晓晔[1] 苏金蓉[1] 李大虎[1,2,3] 吴朋 张永久[1] 梁明剑[1,4] LI Sun-hai;YAN Xiao-ye;SU Jin-rong;LI Da-hu;WU Peng;ZHANG Yong-jiu;LIANG Ming-jian(Earthquake Administration of Sichuan Province,Chengdu 610041,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;China Earthquake Scientific Experimental Site,Sub-cente Sichuan,Chengdu 610041,China;Institute of Geology,China Earthquake Administration,Beijing 100029,China)

机构地区：[1]四川省地震局,成都610041 [2]中国地震局地球物理研究所,北京100081 [3]川滇国家地震监测预报实验场四川分中心,成都610041 [4]中国地震局地质研究所,北京100029

出　　处：《地球物理学进展》2018年第4期1374-1380,共7页Progress in Geophysics

基　　金：科技部公益性行业科研专项"中国地震科学台阵探测-南北地震带南段"(201008001);中国地震局地震星火计划项目(XH16033Y)项目联合资助

摘　　要：为了研究鲁甸M_S 6.5地震的余震空间分布特征和探讨震区深部发震构造,本文利用四川、云南省固定地震台网观测资料和震后流动监测资料,采用双差定位方法对2014年8月3日至11日期间发生的鲁甸M_S 6.5主震及506个M_l≥1.5余震序列进行重新定位,获得了359个事件的重定位结果.研究结果显示:鲁甸主震的震源深度为13.8 km,与震源破裂过程显示的初始破裂深度较为接近,余震序列分布纵剖面还显示出余震主要分布在主震上方,且余震序列呈现出近EW向和NW向的不对称共轭状分布,优势分布方向为NW向的地震序列延展范围约20 km左右,并与昭通—鲁甸断裂相交,近EW向地震序列的延展长度约16 km左右.其中,在垂直NW向密集条带的震源深度剖面上,余震序列呈近于直立的条带状聚集,且余震序列震源深度分布的优势区间为3~15 km,较浅的震源深度说明了地震事件大多发生在脆性上地壳内部.地震重定位结果还表明了发震断层呈现高倾角分布的特征,结合震源机制解和地面地震地质调查及科考成果,综合表明和论证了此次鲁甸MS6.5地震的发震断层与NW向的包谷垴—小河断裂密切相关.In order to study the spatial distribution characteristics of the aftershocks of the Ludian M_S 6. 5 mainshock and to explore the deep seismogenic structure in the area,This paper fully collected the observational data of fixed digital seismic network in Sichuan and Yunnan Province and the mobile monitoring data of postearthquake,we relocated the Ludian MS6. 5 mainshock and its 506 Ml≥1. 5 aftershocks during 3 to 11 August 2014 by using the double-difference algorithm, and finally obtained 359 relocated earthquakes events. Our results show that the focal depth of mainshock is 13. 8 km,which is chose to the initial rupture depth of the mainshock. The profile of aftershock sequence distribution also shows aftershocks are mainly distributed above the mainshock,the aftershocks sequence presents the nearly EW and NW of asymmetric conjugate shape distribution,To the NW distribution direction for the earthquake sequence about extending range of about 20 km,and intersect with zhaotong—Ludian fault, the nearly EW trends of sequence length is about 16 km or so. In the depth profile of the hypocenter of the vertical NW trend, The distribution features aftershock sequence show nearly vertical ribbon aggregation,The dominant interval of aftershock sequence focal depth distribution is 3-15 km, The shallow focal depth indicates that most of the earthquake events occurred inside the brittle upper crust. Our relocated results also shows that the seismogenic fault present high dip angle distribution characteristics. Combining with the focal mechanism and ground geological survey and seismological scientific research, comprehensive results shows and demonstrates the seismogenic fault of the Ludian MS6. 5 earthquake is NW tread direction of the Baogunao-xiaohe fault.

关 键 词：鲁甸MS6.5地震 双差定位 余震序列 发震断层 

分 类 号：P315[天文地球—地震学]