2016年12月8日呼图壁M_S6.2地震序列重定位与发震构造  

RELOCATION OF THE HUTUBI M_S6.2 EARTHQUAKE SEQUENCE ON 8 DECEMBER 2016 AND ANALYSIS OF THE SEISMOGENIC STRUCTURE

作　　者：刘建明[1] 王琼[1] 李金[1] 吴传勇[1] 赵彬彬[1] 孔祥燕[1] LIU Jian-ming;WANG Qiong;LI Jin;WU Chuan-yong;ZHAO Bin-bin;KONG Xiang-yan(Earthquake Administration of Xinjiang Uygur Autonomous Region,Urumqi 830011,China)

机构地区：[1]新疆维吾尔自治区地震局,乌鲁木齐830011

出　　处：《地震地质》2018年第3期566-578,共13页Seismology and Geology

基　　金：国家自然科学基金(41672208);中国地震局地震预测研究所重点援疆项目(2016IES0103);中国地震局地震科技星火计划(XH17043Y)共同资助

摘　　要：基于新疆区域数字地震台网震相观测报告,采用HypoDD方法精确定位了呼图壁M_S6.2地震序列中ML≥1.0地震的震源位置,采用CAP方法反演了主震和余震序列中部分M_L≥4.0地震的震源机制,从而综合分析了呼图壁地震序列的空间分布特征、震源机制和可能的发震构造。结果显示,主震位置为43.775 9°N,86.363 4°E,初始破裂深度约15.388km,震源矩心深度约17km。地震序列沿NWW向单侧扩展,展布长度约15km,震源深度主要分布在5~15km范围。深度剖面显示发震断层面倾向N,运动性质以逆冲为主。主震最佳双力偶震源机制解节面Ⅰ:走向292°/倾角62°/滑动角80°,节面Ⅱ:走向132°/倾角30°/滑动角108°,表明该地震为1次逆冲型地震事件。节面I倾角与震源深度剖面倾角具有较好的一致性,结合余震分布推断节面I为本次地震的发震断层面。综合地震序列空间分布特征、震源机制以及震源区地质构造情况,初步推测呼图壁6.2级地震发震构造可能为齐古背斜以南深部隐伏逆冲断坡上的1条反冲断层。本次地震是天山向准噶尔盆地扩展的应力作用下发生的1次"褶皱型"地震。Based on the digital waveforms of Xinjiang Seismic Network,the Hutubi MS6. 2 earthquake sequence（ ML≥1. 0） was relocated precisely by HypoDD.The best double-couple focal mechanisms of the main shock and aftershocks of ML≥4. 0 were determined by the CAP method. We analyzed the characteristics of spatial distribution,focal mechanisms and the seismogenic structure of earthquake sequence. The results show that the main shock is located at 43. 775 9°N,86. 363 4°E; the depth of the initial rupture and centriod is about 15. 388 km and 17 km. The earthquake sequence extends unilaterally along NWW direction with an extension length of about 15 km and a depth ranging 5 -15 km. The characteristics of the depth profiles show that the seismogenic fault plane dips northward and the faulting is dominated by thrusting. The nodal planes parameters of the best double-couple focal mechanisms are： strike 292°,dip 62° and rake 80° for nodal plane I,and strike 132°,dip 30°and rake 108° for nodal plane Ⅱ,indicating that the main shock is of thrust faulting. The dip of nodal planeⅠ is consistent with the dip of the depth profile,which is inferred to be the fault plane of seismogenic fault of this earthquake. According to the comprehensive analysis of the relocation results,the focal mechanism and geological structure in the source region,it is preliminarily inferred that the seismogenic structure of the Hutubi MS6. 2 earthquake may be a backthrust on the deeper concealed thrust slope at the south of Qigu anticline. The earthquake is a ＂folding ＂earthquake taking place under the stress field of Tianshan expanding towards the Junggar Basin.

关 键 词：呼图壁6.2级地震 HypoDD定位 震源机制 发震构造 “褶皱型”地震 

分 类 号：P315.2[天文地球—地震学]