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工程科学与技术:2021,53(3):53-61
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鲜水河断裂带康定城南新榆林探槽组揭露的破裂特征与地震复发行为
(1.中国地震局 地质研究所,北京 100029;2.桂林理工大学,广西 桂林 541006;3.四川省地震局,四川 成都 610041;4.中铁二院工程集团有限责任公司,四川 成都 610031)
Rupture Characteristics and Seismic Recurrence Behaviors of Xianshuihe Fault Revealed by Xinyulin Trenches, South of Kangding
(1.Inst. of Geology, China Earthquake Administration, Beijing 100029, China;2.Guilin Univ. of Technol., Guilin 541006, China;3.Earthquake Administration of Sichuan Province, Chengdu 610041, China;4.China Railway Eryuan Eng. Group Co. Ltd., Chengdu 610031, China)
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投稿时间:2021-01-09    修订日期:2021-04-02
中文摘要: (古)地震破裂行为是地震危险性评估与重大工程建设抗减震设计的基础资料。鲜水河断裂带是青藏高原东南缘一条强烈活动的左旋走滑断裂,平均30余年就有一次7级以上的地震发生。拟建川藏铁路必经的康定城区一带是鲜水河断裂带古地震研究相对较弱的段落。为获得更为翔实的破裂特征与复发行为,选取康定新城南侧的新榆林一处断陷塘进行探槽组开挖,探槽共计2个,垂直于断陷塘布设,相距约6 m,长度均为18 m,深约3 m。探槽组揭露出宽约5 m的破裂带与构造楔等古地震破裂遗迹。根据断陷塘沉积序列及断层与沉积层的关系,探槽共识别出6次破裂事件,结合探槽20个14C样品AMS测年结果与历史地震记录,事件年代限定为8714BC之前、8304-6316BC、6135-734BC、118BC-27AD、810-1230AD,以及1786年磨西7¾级地震事件。事件序列显示:新榆林一带,早期大震复发间隔较长,约3 000 a左右;自约公元元年以来,活动加剧,复发间隔缩短至700~1 000 a左右,与鲜水河断裂带北段的大震复发行为基本一致。对比和综合前人研究成果,鲜水河断裂带康定城区以南新榆林至二台子一带,大多事件都是同时破裂,但可能存在个别事件,只破裂了二台子一带。1893年以来,鲜水河断裂带再次进入显著的活跃期,鲜水河断裂带北段均发生过破坏性地震;康定以南段自1786年磨西地震后一直趋于平静,未来存在发生地表破裂型强震的可能,在川藏铁路施工及运营过程中,应重点加强大震监测预警。
Abstract:Rupture behaviors of (paleo) earthquakes are the basic data for seismic risk assessment and seismic design of major engineering constructions. Xianshuihe fault is the most active left-lateral strike-slip fault of the southeastern margin of the Tibetan Plateau. An earthquake of magnitude 7 or higher occurred every 30 years on average. Kangding Downtown area where the proposed Sichuan-Tibet Railway passing through is a relatively weak segment of Xianshuihe fault in paleo-seismic research. In order to obtain more detailed rupture characteristics and recurrence behaviors, we selected a depression pond at the Xinyulin site on the south side of Kangding new town to excavate the trench group. Two trenches arranged perpendicular to the fault pond were designed and studied, each trench with a total length of 18 meters, 3 meters deep, and 3 meters wide. Five meters wide rupture zone, seven sets (three categories) of sedimentary strata with clear boundaries and a series of paleoearthquake remains such as structural wedges were revealed in the trenches. According to the division of stratus and the relationship between faults and stratus, a total of 6 rupture events were summarized in the trenches, Combining the twenty 14C AMS dating results and historical seismic records, the events were limited in order: before 8714BC, 8304-6316BC, 6135-734BC, 118BC-27AD, 810-1230AD, and Kangding South M7¾ earthquake event in 1786. The modeled date shows that Near Xinyulin Village, the early recurrence interval of rupture events is relatively long (about 3000 years), and the activity has intensified since around AD, the recurrence interval has been shortened to about 700~1000 years, which is basically the same as the large earthquake recurrence habits in the North segment of Xianshuihe fault Belt. Comparison and synthesis with the previous research results, most of the events from Xinyulin to Ertaizi south of Kangding, Xianshuihe fault ruptured at the same time, but there may be some events that only ruptured near Ertaizi. Since 1893, Xianshuihe fault has entered a significant active period again. Destructive earthquakes have occurred in the northern segment of the Xianshuihe fault zone, while the southern segment of Kangding has been calming since the Moxi earthquake in 1786, and there is a possibility of strong earthquake with surface rupture in the future. Along the construction and operation of Sichuan-Tibet Railway, the monitoring and early warning of major earthquakes should be strengthened.
文章编号:202100031     中图分类号:    文献标志码:
基金项目:第二次青藏高原科学考察研究(2019QZKK0901);中国铁路总公司科技研究开发计划重点课题(2017G008-F);国家自然科学基金项目(41372218);中国地震局地质研究所基本科研业务专项(IGCEA1418)
作者简介:第一作者:高帅坡(1991-),男,博士生.研究方向:构造地质学.E-mail:gspabc@163.com;通信作者:陈立春,E-mail:glutclc@glut.edu.cn
引用文本:
高帅坡,陈立春,梁明剑,王栋,李彦宝,韩明明,冯嘉辉,卢丽莉.鲜水河断裂带康定城南新榆林探槽组揭露的破裂特征与地震复发行为[J].工程科学与技术,2021,53(3):53-61.
GAO Shuaipo,CHEN Lichun,LIANG Mingjian,WANG Dong,LI Yanbao,HAN Mingming,FENG Jiahui,LU Lili.Rupture Characteristics and Seismic Recurrence Behaviors of Xianshuihe Fault Revealed by Xinyulin Trenches, South of Kangding[J].Advanced Engineering Sciences,2021,53(3):53-61.