新疆巴里坤1842年和1914年2次M7^1/2历史地震地表破裂的几何展布及特征  

GEOMETRIC DISTRIBUTION AND CHARACTERISTICS OF THE SURFACE RUPTURE OF TWO HISTORICAL EARTHQUAKES IN THE BARKOL BASIN,XINJIANG

作　　者：徐良鑫[1,2] 冉勇康 梁明剑[3] 吴富峣[4] 高帅坡 王虎 XU Liang-xin;RAN Yong-kang;LIANG Ming-jian;WU Fu-yao;GAO Shuai-po;WANG Hu(Key Laboratory of Active Tectonics and Volcano,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Academy of Seismic Engineering Surveys,Shaanxi Earthquake Agency,Xi′an 710068,China;Sichuan Earthquake Agency,Chengdu 610041,China;Development and Reform Research Center of Enshi,Hubei Province,Enshi 445000,China;Faculty of Geosciences and Environmental Engineering,Southwest Jiaotong University,Chengdu 611756,China)

机构地区：[1]中国地震局地质研究所,活动构造与火山重点实验室,北京100029 [2]陕西省工程地震勘察研究院,西安710068 [3]四川省地震局,成都610041 [4]湖北省恩施州发展改革研究中心,恩施445000 [5]西南交通大学,成都611756

出　　处：《地震地质》2020年第1期1-17,共17页Seismology and Geology

基　　金：全国重点监视防御区活动断层地震危险性评价(1521044025)子项目“巴里坤盆地南缘断裂填图”、陕西省自然科学基础研究计划项目(2020JQ-980);国家自然科学基金(41402185)共同资助。

摘　　要：地震地表破裂带是断裂活动最为直观的地貌证据,其破裂样式、同震位移量及空间几何展布特征是判定活动断裂分段及长期活动习性的重要依据。文中在对新疆巴里坤盆地开展活动断裂调查研究的过程中,综合遥感解译、野外断裂踏勘、小型无人机航拍、地表断错位移分析以及古地震槽探等方法,根据在巴里坤盆地南缘断裂西段的雄库尔—邵家庄之间和巴里坤盆地中央东部等多处新发现的总体呈EW向展布的最新地表构造形变遗迹,并对比历史文献记载中这2次地震震害的分布特征,进一步厘定了巴里坤1842年和1914年2次M 71/2历史地震地表破裂的空间展布及特征。结果表明,沿巴里坤盆地南缘断裂西段分布的1842年M 71/2地震地表破裂带的同震运动以左旋走滑为主,在雄库尔与巴里坤县城之间呈雁列状展布,且自西向东还具有向巴里坤盆地中央扩展的趋势。新厘定的地表破裂带长度至少可达65km,最大水平位错量出现在雄库尔—洛包泉一带,多个冲沟水系的同震位错平均观测值为(4.1±1.0)m,并具有约4m的特征位移量,由此推断1842年M 71/2历史地震的震中位置应在雄库尔—洛包泉一带。此外,位于巴里坤盆地中央东部的奎苏镇—伊吾盆地盐池乡附近的褶皱盲断层带应是1914年M 71/2地震的发震构造,该地震的地表变形带全长约90km,表现为河漫滩等最新地貌面和冲积砾石层的显著褶皱变形,并且有多处露头剖面显示与同震褶皱变形伴生的弯矩断层已断错至地表。因此,1914年M 71/2地震的震中位置应在地表构造形变最为显著的奎苏镇东附近。文中取得的研究结果不仅进一步更新和完善了对巴里坤盆地2次历史地震震中位置及发震断裂的认识,并可为分析区域地震危险性提供重要的参考资料。Surface rupture zone of historical earthquake is the most intuitive geomorphological response to fault activity.The rupture pattern,coseismic displacement and its geometric spatial distribution are important for determining segmentation and long-term movement behaviors of active fault.In the Barkol Basin of Xinjiang,according to the comprehensive result from remote sensing image interpretation,field surgery,high-resolution small unmanned aerial vehicles photography,terrain deformation measurements and trench excavation on geomorphological points,not only the new surface ruptures of the two M 71/2 historical earthquakes in Barkol in 1842 and 1914 were found and defined between Xiongkuer and the southwest of Barkol County in southwestern part of the basin,but also the latest deformation evidence of the EW fold-up faults in the eastern part of the Basin was identified.Combined with the ancient document analysis of the two historical earthquakes,we finally conclude that the surface rupture zone in the western segment on the southern margin of the Barkol Basin is the seismogenic structure of the M 71/2 earthquake in 1842.The surface rupture zone is mainly characterized by left-lateral strike-slip,roughly with en echelon arrangement spreading from Xiongkuer to the south of Barkol County.The length of the surface rupture zone determined by field investigation is at least about 65km,and the maximum horizontal displacement appears around the Xiongkuer Village.At the same time,the surface rupture zone gradually shows more significant thrust extrusion from west to east,and has a tendency of extension towards the central of the Barkol Basin.The average observed displacement of the entire surface rupture obtained by counting the coseismic offsets of multiple faulted gullies is(4.1±1.0)m,with the coseismic characteristic displacement of^4m.The epicenter position should appear at the place with the largest horizontal dislocation amount near Xiongkuer Village.In addition,the length of the fold-blind fault zone in the vicinity o

关 键 词：东天山 巴里坤 历史地震 地表破裂带 发震构造 

分 类 号：P315.2[天文地球—地震学]