郯庐断裂带中段F_(5)断裂淮河—女山湖段的古地震与垂直滑动速率  

PALEOEARTHQUAKES AND VERTICAL SLIP RATES ON THE HUAI RIVER—NüSHAN LAKE SEGMENT OF FAULT F_(5) IN THE MIDDLE SECTION OF THE TANLU FAULT ZONE

作　　者：杨源源[1,2] 李鹏飞 路硕 疏鹏[1] 潘浩波 方良好[1] 郑海刚 赵朋[1] 郑颖平 姚大全[1] YANG Yuan-yuan;LI Peng-fei;LU Shuo;SHU Peng;PAN Hao-bo;FANG Liang-hao;ZHENG Hai-gang;ZHAO Peng;ZHENG Ying-ping;YAO Da-quan(Anhui Earthquake Agency,Hefei 230031,China;Anhui Mengcheng National Geophysical Observatory,Bozhou 233527,China)

机构地区：[1]安徽省地震局,合肥230031 [2]安徽蒙城地球物理国家野外科学观测研究站,亳州233527

出　　处：《地震地质》2022年第6期1365-1383,共19页Seismology and Geology

基　　金：国家自然科学基金(41802224);安徽省公益性地质项目(2015-g-25)共同资助。

摘　　要：郯庐断裂带中段安丘-莒县断裂(F_(5))为中国东部重要的地震活动断裂,其最南段展布于淮河—女山湖之间,长约20km,最新活动时代为全新世早期。针对F_(5)断裂淮河—女山湖段的前期工作侧重于在不同地段开挖探槽以揭示断裂的最新活动时代、结构特征及运动性质,并报道了零星的古地震事件。本次在该段选取关键地段开挖探槽并结合前期探槽资料,开展了古地震事件的综合对比研究;通过测量探槽附近断层陡坎的高度,并结合相关地层测年数据,计算了断裂的垂直滑动速率;基于该段古地震研究成果,结合其他学科资料,分析了苏皖交界地区的地震危险性。研究表明:(1)F_(5)断裂淮河—女山湖段中更新世晚期以来至少发生过5次古地震事件,厘定的最近2次事件的年代为20.36~(18.7±0.3) ka BP和10.92~7.83ka BP;(2)F_(5)断裂淮河—女山湖段紫阳山一带的垂直滑动速率约为0.05mm/a,陡山一带的垂直滑动速率约为0.07mm/a,该段整体属于弱活动断层;(3)F_(5)断裂泗洪—明光段为历史地震地表破裂空段,最近1次古地震的离逝时间较长,现今小地震不活跃,闭锁程度较高,易于应力积累,存在发生7级及以上强震的危险性。The Anqiu-Juxian Fault(F_5) in the middle part of Tanlu fault zone is the most important seismically active fault in eastern China.The Fault F_5is divided into the Anqiu-Juxian section,the Juxian-Tancheng section and the Xinyi-Sihong section,each of which is an independent rupture unit.There are no historical records about earthquakes with magnitude above 5 in the Xinyi-Sihong section,but it is revealed that there are Holocene paleoseismic events,so this section is a significant gap segment of surface rupture of historical earthquakes.In recent years,an important progress in the study of neotectonic activity of Xinyi-Sihong section of F_5 is to find that it extends southward to the region between Huai River and Nüshan Lake in Anhui Province,with a length of about 20km.The fault spreads on the gentle slope on the edge of Cretaceous red sandstone uplift(hillock) along the line from Fushan to Ziyangshan,and the latest activity can date back to the early Holocene.At present,there is a clear understanding of the geometric distribution,structural characteristics and activity nature of the Huai River—Nüshan Lake section of F_5(F_5-HRNL),but the paleoseismic research is relatively weak,the revealed paleoseismic events are relatively sporadic,and the research results are from single trench,so there is a lack of comprehensive and comparative analysis from multiple trenches.In addition,the study on slip rate has not been carried out in this section,which affects the understanding of the overall activity level of the fault.Therefore,based on the previous work,paleoseismic research is carried out by excavating trenches in key locations,and more reliable paleoseismic events are determined through comprehensive comparative analysis of multiple trenches.The vertical slip rate of the fault is calculated by measuring the height of the fault scarp near the trench and combining with the dating data of relevant strata.Based on the paleoseismic research results of the F_5-HRNL and combined with the data of other disciplines,the se

关 键 词：郯庐断裂带 F_(5)断裂 垂直滑动速率 全新世 古地震 

分 类 号：P315.2[天文地球—地震学]