摘要
NW向的鲜水河断裂带乾宁—康定段由3条分支断裂组成,自东向西分别为雅拉河断裂、色拉哈断裂和折多塘断裂,这3条断裂自全新世以来均有明显的活动。雅拉河断裂、色拉哈断裂和折多塘断裂南段分别发生过1700年7级、1725年7级和1955年7.5级地震。1︰50000的鲜水河活动断裂带地质图(1995)及现有相关研究结果表明,折多塘断裂全新世活动段南起折多塘村附近,向N至康定机场附近,全长约30km,该段也是1955年7.5级地震地表破裂带展布的位置,而康定机场以北的西北段没有全新世活动的报道。文中通过影像解译,结合野外地质调查,发现折多塘断裂西北段全新世活动的新证据。经实地调查与探槽开挖等工作核实,该活动段自SE起于康定机场北侧,向NW延伸到多日阿嘎莫村,呈NW向展布,NW端邻近色拉哈断裂北段。文中结果表明折多塘断裂在全新世的活动范围较前人的研究成果向NW延伸了15km。该发现为完善鲜水河断裂带乾宁—康定段的折多塘断裂、色拉哈断裂以及雅拉河断裂这3支活动断裂的平面几何图像提供了一些依据,对深入认识鲜水河断裂带康定段在各分支断裂上的应变分配、强震破裂模式等方面具有重要意义。
Xianshuihe Fault is an active fault which originated from the eastern margin of the Tibetan plateau and formed by the orogenic events in Songpang-Ganzi area.The origin of Xianshuihe Fault is discovered in the NW of Ganzi,then it extends to the SE,passing through Luhuo,Daofu,Qianning,Kangding,Luding,Moxi and disappears after passing through Shimian.Based on previous studies,Xianshihe Fault is a sinistral strike-slip fault.According to GPS and InSAR data,the horizontal component of average slip rate for Xianshuihe Fault is approximately 7.5~16.7mm/a.As a crucial member of the regional earthquake zone,Xianshuihe Fault separates Sichuan-Yunnan block and Bayankala block.More importantly,Xianshuihe Fault is responsible for a great number of large magnitude earthquakes especially in the Qianning-Kangding segment,a segment of Xianshuihe Fault which consists of three branches.From east to west,they are Yalahe Fault,Selaha Fault and Zheduotang Fault which are all active since Holocene.Yalahe Fault is responsible for a M 7 earthquake that occurred around 1700AD.Selaha Fault is responsible for anothe r M 7 earthquake which occurred around 1725AD.Around 1955AD,a M 7.5 earthquake occurred which was related to Zheduotang Fault.According to the 1:50k Xianshihe Active Faults Map(1995)and relevant researches,it is discovered that,from north to south,the Holocene active Zheduotang segment starts from Kangding airport to Zheduotang village.The total length of Zheduotang segment is around 30km which includes the surface rupture zone of the 1955 M 7.5 earthquake.Due to the absence of researches,the northern part of the Zheduotang Fault,which is to the north of the Kangding airport,remains unstudied.Based on satellite image,we discovered that there are signs of faults to the north of Kangding airport.Therefore,we selected four sites to carry out field investigations and trench analysis.The first site is to the NW of the Duoriagamo village.Based on satellite image and DEM data,many typical faulted geomorphologic features are discovered.
作者
马骏
周本刚
王明明
安力科
MA Jun;ZHOU Ben-gang;WANG Ming-ming;AN Li-ke(Key Laboratory of Active Tectonics and Volcano,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Sichuan Earthquake Agency,Chengdu 610041,China;School of Earth Science,University of Western Australia,Perth 6009,Australia)
出处
《地震地质》
EI
CSCD
北大核心
2020年第5期1021-1038,共18页
Seismology and Geology
基金
中国地震局地质研究所基本科研业务专项(IGCEA1824)
中国地震局地震科技星火计划项目(XH18040)共同资助。
关键词
青藏高原
鲜水河断裂带乾宁—康定段
折多塘断裂西北段
断裂活动性
古地震
Tibetan plateau
Qianning-Kangding segment of Xianshuihe fault zone
the NW branch of Zheduotang Fault
fault activity
paleoseismicity
