利用断错地貌限定榆木山北缘断裂最新地震事件  

Determination of the latest seismic event on the northern Yumushan Fault by faulted landforms

作　　者：赵晓明 刘兴旺[1,2] 蔡艺萌 邹小波 姚赟胜 ZHAO Xiaoming;LIU Xingwang;CAI Yimeng;ZOU Xiaobo;YAO Yunsheng(Lanzhou Institute of Seismology,China Earthquake Administration,Lanzhou 730000,Gansu;Gansu Lanzhou Geophysics National Observation and Research Station,Lanzhou 730000,Gansu)

机构地区：[1]中国地震局兰州地震研究所,甘肃兰州730000 [2]甘肃兰州地球物理国家野外科学观测研究站,甘肃兰州730000

出　　处：《第四纪研究》2022年第3期732-743,共12页Quaternary Sciences

基　　金：甘肃省地震局地震科技野外站基金项目(批准号:2021Y12);国家自然科学基金项目(批准号:42072246)共同资助。

摘　　要：榆木山北缘断裂位于河西走廊中段榆木山山前,是榆木山隆起与河西走廊之间的分界断裂。研究榆木山北缘断裂的断错地貌与活动特征,有助于进一步了解该地区的地震危险性及历史地震的归属问题。本研究通过遥感影像解译、野外地质调查及无人机航空摄影测量,获得了研究点高精度DEM数据,并利用数据进行了微地貌分析,详细区分了榆木山北缘断裂被断错及未断错的洪积扇,根据断错特征使用^(14)C测年方法对洪积扇进行了定年,对榆木山北缘断裂最新地震事件进行了限定。结果表明,榆木山北缘断裂未断错的早期洪积扇年代为2775~2940 cal.a B.P.,表明断裂最新一次地震活动发生在2775~2940 cal.a B.P.之前。综合前人研究结果,榆木山北缘断裂的最新一次地震事件限定在约2775~2940 cal.a B.P.至3940~4155 cal.a B.P.之间,该结果不支持公元180年表氏(高台)7级地震发生在榆木山北缘断裂上的观点。榆木山北缘断裂古地震离逝时间较长,已接近或超过地震复发间隔,具有较高的地震危险性。The Hexi Corridor is a seismically active foreland basin which is located between the Gobi-Alashan block to the north and the Qilian Shan to the south. Many active faults have developed in and around this area,some of which have caused destructive earthquakes. The northern Yumushan fault is located in front of Yumu Shan in Hexi Corridor,which is the boundary fault between Hexi Corridor and Yumu Shan uplift. Some researches show that the is a Holocene advice fault,and is the seismogenic fault of the Biaoshi( Gaotai) M7 1/2 earthquake in 180 A.D.However,some researchers believe that the earthquake occurred on the Helishan fault. Thus,a study on the activity characteristics of the northern Yumushan fault will contribute to understanding the earthquake risk and historical earthquake belonging in the region. In this paper,high-resolution DEM data of the research points are obtained through remote sensing image interpretation,field geological survey,and UAV aerial photogrammetry. Then,microgeomorphic analysis is carried out by using the data,and the faulted and non-faulted alluvial fans of the northern Yumushan fault are divided in detail. Alluvial fans of the different periods are developed in front of Yumu Shan.There are usually 4 ~ 5 periods of alluvial fans preserved along the northern Yumushan fault. In addition to the developing A0 alluvial fan,according to Radiocarbon dating of loess deposition of alluvial fan,we determine the age of 1830 ~ 1992 cal. a B. P. to 2775 ~ 2940 cal. a B. P. and 8975 ~ 9032 cal. a B. P. for A1 alluvial fan and A2alluvial fan,respectively. The northern Yumushan fault generally does not fault the A0 and A1 alluvial fans,reflecting that the fault has been inactive since approximately 2775 ~ 2940 cal. B. P. Based on the age of faulted A2alluvial fan,the latest event of the fault can be determined to 2775 ~ 2940 cal. a B. P. to 8975 ~ 9032 cal. a B. P.Combined with the research results of paleoearthquakes,the latest seismic event on the northern Yumushan fault is determined to be approxima

关 键 词：河西走廊 断错地貌 历史地震 榆木山北缘断裂 

分 类 号：P546[天文地球—构造地质学]