东昆仑断裂带库赛湖段晚第四纪古地震研究  

LATE QUATERNARY PALEOSEISMIC HISTORY ON THE KUSAI LAKE SEGMENT OF EAST KUNLUN FAULT ZONE IN NORTHERN TIBET

作　　者：胡道功[1] 吴中海[1] 吴珍汉[1] 赵希涛[2] 叶培盛[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]中国科学院地质与地球物理研究所,北京100029

出　　处：《第四纪研究》2007年第1期27-34,共8页Quaternary Sciences

基　　金：中国地质调查局国土资源大调查项目"青藏铁路活动断裂调查与监测"项目(批准号:1212010541403);科技部国际合作重点计划"青藏高原深部过程与地表效应"项目(批准号:2001CB711001)共同资助

摘　　要：对东昆仑断裂带库赛湖段进行了断错地貌填图和古地震探槽揭露研究。除2001年昆仑山口西8.1级地震外,共揭露出9次古地震事件,它们的年龄分别为31900±1923aB.P.,27990±1681aB.P.,23635±1427aB.P.,20345±1225aB.P.,16865±1018aB.P.,12935±774aB.P.,9730±592aB.P.,6955±425aB.P.和3100±201aB.P.;古地震重复间隔分别为3910±2554a,4355±2205a,3290±1881a,3480±1593a,3930±1279a,3205±975a,2775±728a,3855±470a和3100±201a。研究结果表明,库赛湖段晚第四纪古地震活动具有准周期性,其平均重复间隔为3544±416a。发生在距今3100年前的倒数第1次古地震事件的离逝时间与重复间隔非常接近,这意味着2001年11月14日发生在库赛湖段的8.1级大地震为该断裂地震活动在准周期上的再现。高的滑动速率和长周期复发间隔表明库赛湖段活动习性以重复发生大地震为特征。The East Kunlun fauh zone in northern Tibetan Plateau is a typical active fault zone, characterized by sinistral strike-slip faults. Field investigation indicates that there are a lot of relics along the fault traces of the Kusai Lake segment, Kunlun Fault. The relices include push-up, pull-apart basins, sag pond, and earthquake fault scarps. This implies that the Kusai Lake segment of the Kunlun Fault is a seismogenic fault on which surface-rupturing earthquakes often occur in regular or irregular intervals. To determine the chronology of Late Quaternary surface ruptures of this part of the Kunlun Fault, five trenches were excavated. All sediment samples collected from the trenches were dated by using thermoluminescence （TL） method. Paleoseismic evidence, combined with TL dating, show that the Kusai Lake segment of the Kunlun Fault has generated at least 9 paleoearthquakes since Late Quaternary, whose ages are 31900 ± 1923aB. P., 27990 ± 168laB. P., 23635 ± 1427aB. P., 20345 ± 1225aB. P., 16865 ± 1018aB. P., 12935 ± 774aB. P., 9730 ± 592aB. P., 6955 ± 425aB. P. , and 3100 ± 201aB. P., respectively. The recurrence interval between two adjacent events is 3910 ± 2554a,4355 ± 2205a,3290 ± 1881a,3480 ± 1593a,3930 ± 1279a,3205 ± 975a,2775 ± 728a, 3855 ±470a, and 3100 ± 201a, respectively. Its average recurrence interval is 3544 ± 416a. It shows that recurrence of these events is uniform with time, and suggests that the Kusai Lake segment of the fault displays timedependent seismic behavior. These results have significant implications for seismic hazard assessment in the Kusai Lake segment of the fault. On Nov. 14, 2001, a great earthquake with magnitude of 8.1 occurred along the Kusai Lake segment. The surface rupture has a length of 426km with a maximum left-lateral co-seismic displacement of 6.4m. The penultimate great earthquake occurred before 3100a, coherenting with the average recurrence interval.

关 键 词：古地震 晚第四纪 地震复发间隔 东昆仑断裂库赛湖段 

分 类 号：P315.2[天文地球—地震学] P534.63[天文地球—固体地球物理学]