临泽断裂新活动特征初步研究  

Preliminary Study of New Faulting Characteristic of the Linze Fault

作　　者：庞炜[1] 何文贵[2,3] 张波 PANG Wei;HE Wengui;ZHANG Bo(Second Crust Monitoring and Application Center,China Earthquake Administration,Xi an 710054,Shaanxi,China;Lanzhou Institute of Seismology,China Earthquake Administration,Lanzhou 730000,Gansu,China;Gansu Earthquake Agency,Lanzhou 730000,Gansu,China)

机构地区：[1]中国地震局第二监测中心,陕西西安710054 [2]中国地震局兰州地震研究所,甘肃兰州730000 [3]甘肃省地震局,甘肃兰州730000

出　　处：《地震研究》2019年第1期120-132,I0002,共14页Journal of Seismological Research

基　　金：中国地震局地震行业科研专项(201408023);中国地震局震情跟踪定向工作任务(2019010212;2018010203);中国地震局第二监测中心科学技术基金(KJ17010)联合资助

摘　　要：临泽断裂在地貌上可见3条断层陡坎,总体走向NNW,最长约8 km,东侧和中间陡坎主体倾向E,西侧陡坎倾向W。①利用差分GPS对3条断层陡坎进行了详细的测量,发现临泽断层陡坎较低,局部发育多级断层陡坎,坡角较缓,高度几十厘米至1米多;②在临泽断裂上选取4个探槽剖面进行古地震分析、样品采集和年代测试,发现东侧和中间的断层陡坎为正断层所控制,西侧的断层陡坎为逆断层所控制;③探槽开挖揭露出晚更新世晚期以来,临泽断裂上发生过4次古地震事件,时间分别为(8 895±125)a B.P.之前、(7 245±75)a B.P.～(6 190±20)a B.P.、(5120±20)a B.P.～(4.8±0.5)ka和(2 550±50)a B.P.～(2 326±64)a;④全新世以来可以确定3次事件,较早一次事件与榆木山北缘断裂上较早一次古地震事件时间比较吻合,说明临泽断裂可能是榆木山断裂向河西走廊内部继续活动的延伸;最后一次古地震事件的离逝时间约为2 500 a,表明临泽断裂全新世活动一直比较强烈。The Linze fault includes three fault scarps,of which the middle and east scarps facing east,while the west scarp facing west,mainly striking NNW direction with the length up to 8 km,have been discovered.①Three fault scarp are measured in detail by differential GPS. The profiles show that the Linze fault scarps are much lower,and multi-level fault scarp are locally developed,with gentle slope angle and a height from tens of centimeters to one meter.② Four trench profiles on Linze fault are selected for paleoseismic analysis,sample collection and dating. It is found that the fault scarps in the east and middle are controlled by normal faults,while the fault scarps in the west are controlled by reverse faults.③Since late Late Pleistocene,four rupture events happened respectively before(8 895±125) a B.P.,(7 245±75) a B.P.^(6 190±20) a B.P.,(5 120±20) a B.P.^(4.8±0.5) ka and(2 550±50) a B. P.^(2 326±64) a.④Three events can be identified since Holocene. The earlier one coincides with the earlier paleoearthquake event on the northern margin fault of Yumushan,which indicates that Linze fault may be the extension of Yumushan fault to the Hexi Corridor. The last paleoearthquake event elapsed about 2 500 a,which indicates that the Linze fault is active during Holocene.

关 键 词：临泽断裂 榆木山断裂 古地震 陡坎形态 差分GPS测量 

分 类 号：P315.242[天文地球—地震学]