A Preliminary Study on the New Activity Features of the Lajishan Mountain Fault Zone in Qinghai Province

作     者：Yuan Daoyang Zhang Peizhen Lei Zhongsheng Liu Baichi Liu Xiaolong 

作者机构：Lanzhou Base of Institute of Earthquake Prediction CEA Lanzhou 730000 China Institute of Geology China Earthquake Administration Beijing 100029 China 

出 版 物：《Earthquake Research in China》 (中国地震研究（英文版）)

年 卷 期：2005年第19卷第4期

页      面：391-401页

学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学] 

基　　金：ThisstudywassponsoredbyNationalNaturalSciencesFoundationofChina(ProjectNumber40372086) thekeyprojectsofNationalNaturalSciencesFoundationofChina(No.40234040) andJointEarthquakeScienceFoundation CEA(No.102055).Contributionnumber:LC2004009ofLanzhouBaseofInstituteofEarthquakePrediction CEA 

主　　题：Lajishan Mountain Active fault Historical earthquake New activity 

摘      要：The Lajishan Mountain fault zone consists of two NE_protruding arcuate faults, i.e. the northern and southern margin fault of Lajishan Mountain with the fault length of 230km and 220km respectively. The fault zone is located in the large_scale compressional structure zone and tectonic gradient zone in_between the NNW_trending right_lateral strike_slip Reshui_Riyueshan fault zone and the NWW_trending left_lateral strike_slip northern margin of west Qinling Ranges fault zone is also an important boundary fault zone, separating the Xining_Minhe basin and the Xunhua_Hualong basin at the southern and northern sides of the Lajishan Mountain respectively. Geologic geomorphic evidences of new activity revealed by field investigations indicate that the latest movement of the Lajishan fault zone was in late Epipleistocene (only a few segments were active in early Holocene) and is mainly of compressive thrusting with slightly left_lateral strike_slip component. The above movement has possibly resulted in the occurrence of about 20 moderate earthquakes of magnitude around 5.0. The Lajishan region can therefore be regarded as a seismotectonic window to reflect tectonic movement and earthquake activity.