地震工程学报2016，Vol.38Issue(4)：632-637,668,7.DOI:10.3969/j.issn.1000-0844.2016.04.0632
昌马断裂带古地震活动特征的新认识
New Insight on Paleoearthquake Activity along Changma Fault Zone
摘要
Abstract
The Changma fault consists of four sub-faults,and is an important transform fault loca-ted between the Altyn Tagh fault and the western segment of the Qilian Mountains.In 1932,a M7.6 earthquake occurred in the fault,forming a rupture with a length of approximately 120 km that is composed of a series of fissures,fault scarps,offset terraces,and gullies.The maximum horizontal and vertical coseismic displacement was up to 5 .5 m and 1 .9 m,respectively.A trench excavated at Choushuiliugou in the middle-eastern segment of the Changma fault shows evidence of two paleoearthquakes:one is the Changma earthquake (1932)and the other earthquake oc-curred after 902 ± 44 a B.P..Combined with the results of previous studies,it was determined that seven paleoearthquakes have occurred in the Holocene.Base on characteristic earthquake model,we speculate an earthquake recurrence interval of approximately 1 ka,and part of paleo-earthquake events are not revealed by the trench.The trench also shows that the dip direction of the layer on the hanging wall is opposite to that of the down wall and low-angle fault.Based on a survey of dislocation landforms,the ratio of horizontal shortening and left strike slip was found to be 1∶5 .Eastern extrusion occurred in relation to the influence of Altyn Tagh fault activities in the study area.The change in fault trend has resulted in regional stress and differing angles between some of the fault segments,particularly the tip of sub-faults.Active fault characteristics are shown predominantly as sinistral strike-slip,but there is an evident increase in the component of horizon-tal shortening,which forms nappe activities on the hanging wall.It also forms a specific low-angle strike-slip phenomenon,which illustrates that the Changma fault has prominently presented crus-tal shortening since the late Pleistocene,in addition to absorbing much of the sinistral displace-ment of the Altyn Tagh fault,and playing a significant role in the tectonic transition between the Altyn Tagh fault and a series of faults in the western segment of the Qilian mountains.关键词
古地震事件/地震复发间隔/低角度逆断层/昌马断裂Key words
paleoearthquake/earthquake recurrence interval/low-angle thrust fault/Changma fault分类
天文与地球科学引用本文复制引用
罗浩,何文贵,袁道阳,邵延秀,王庆民..昌马断裂带古地震活动特征的新认识[J].地震工程学报,2016,38(4):632-637,668,7.基金项目
中国地震活断层探察-南北地震带北段项目(20140802306) （20140802306）
国家自然基金项目(40872132) （40872132）
