郯庐断裂带安丘-莒县断裂江苏段古地震研究新进展  

NEW PROGRESS IN PALEOEARTHQUAKE STUDIES OF THE JIANGSU SEGMENT OF THE ANQIU-JUXIAN FAULT IN THE TANLU FAULT ZONE

作　　者：张浩 李丽梅[1] 蒋新[1] 章东 许汉刚[1] ZHANG Hao;LI Li-mei;JIANG Xin;ZHANG Dong;XU Han-gang(Jiangsu Earthquake Agency,Nanjing 210014,China)

机构地区：[1]江苏省地震局,南京210014

出　　处：《地震地质》2023年第4期880-895,共16页Seismology and Geology

基　　金：新沂市活动断层探测与地震危险性评价项目;江苏省地震局青年科学基金(201802,202106,202203)共同资助

摘　　要：郯庐断裂带是中国东部活动性最强的断裂带,郯庐断裂带江苏段主要由5条分支断层组成,并于更新世强烈活动,其中安丘-莒县断裂持续活动至全新世,是1668年郯城8½级特大地震的发震断裂。文中采用古地震探槽方法研究安丘-莒县断裂江苏段全新世以来的古地震事件,并采用^(14)C测年方法确定古地震的时间。结合前人通过探槽揭露的古地震时间进行综合分析,认为安丘-莒县断裂江苏段全新世以来共有3次古地震事件,时间分别为距今300a以来、距今约6000a和11000a,垂直同震位移均约1m。1668年郯城8.5级地震在安丘-莒县断裂新沂段山前出露区存在地表破裂的迹象,在隐伏区表现为大量喷砂冒水现象,在探槽揭露的晚全新世地层中有密集的裂缝和砂脉。Paleoseismology is a discipline that studies prehistoric earthquakes or earthquakes that occurred before instrumental records using geological and geomorphological methods,mainly by trench excavation and Quaternary chronology.It focuses on the time and intensity distribution of large earthquakes,to reveal the recurrence characteristics of large earthquakes and provide basic data for evaluating the probability of future earthquakes.The Tanlu fault zone is the most active fault zone in eastern China.The Jiangsu section of the Tanlu fault zone is mainly composed of five branch faults,which are strongly active in the Pleistocene.Among them,the Anqiu-Juxian Fault continued to be active until the Holocene,which is the seismogenic fault of the Tancheng 8½earthquake in 1668.The Xinyi-Sihong section is likely to generate strong earthquakes in the future in the south-central section of the Tanlu fault zone.The total length of the Jiangsu section of the Anqiu-Juxian Fault is about 170km,with an overall strike of 5°~15°,extending southwards from the north Maling Mountain to the Chonggang Mountain.The geomorphic features are distributed from north to south by the alternation of the bedrock mountain and the sedimentary basin.The Anqiu-Juxian Fault shows a single exposed fault on one side of the bedrock mountain,extending to the basin into two branches in the east and west,of which the east branch is the active late Pleistocene Fault and the west branch is the Holocene active fault.The Jiangsu section of the Anqiu-Juxian Fault is dominated by dextral strike-slip and has both dip and thrust components.Lots of research have been done on the ancient earthquakes of the Anqiu-Juxian Fault.The trenches are mostly located in Maling Mountain,Zhangshan Mountain and Chonggang Mountain,which are in the state of uplift and denudation.The Holocene is very thin,and the dating method is mostly optical luminescence.The identification of ancient earthquake events is less since the Holocene,with the accuracy of ancient earthquake time not hig

关 键 词：安丘-莒县断裂江苏段 古地震 地表破裂 

分 类 号：P315.2[天文地球—地震学]