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Title:: Analysis of Locking and Seismic Risk of the Altyn Tagh Fault based on GPS Data

Author(s):: LIU Lei; ZHAO Ningyuan; WANG Yang; (The Second Monitoring and Application Center,China Earthquake Administration,Xi'an 710054,Shannxi,China)

Keywords:: the Altyn Tagh fault; negative dislocation inversion with Tdefnode; fault locking degree; seismic risk

摘要:: 采用1991—2015年GPS速度场数据,分析了阿尔金断裂现今滑动速率特征; 利用Tdefnode负位错反演程序计算了阿尔金断裂的闭锁程度分布及滑动亏损速率分布; 结合小震分布特征,对阿尔金断裂地震危险性进行了研究。结果表明:阿尔金断裂西段、中段和东段的走滑速率分别为7.1 mm/a,7.8 mm/a,5.0 mm/a,在与北西向断裂交汇区域速率减小最快; 断裂闭锁程度较高区域集中在断裂中东段,断裂中段亏损速率为6～8 mm/a,到东段亏损速率增加到10 mm/a; 结合震源深度剖面认为断裂中东段是一个地震空段,地震危险性较高,未来应该加强关注。

Abstract:: By using the GPS velocity field during 1991～2015,we analyze the slip rate of the Altyn Tagh fault,and then we invert the fault locking and slip deficit of the Altyn Tagh fault by negative dislocation inversion with Tdefnode code.Moreover,combining with the distribution characteristics of small earthquakes,we analyze the seismic risk of the Altyn Tagh fault.The results show that the slip rate of the western segment is 7.1 mm/a,the middle segment is 7.8 mm/a,and the eastern segment is 5.0 mm/a.The slip rate decreases in the intersection with NW faults.The middle-eastern segments of the fault is completely locked.And the slip deficit rate of the middle segment is about 7～8 mm/a,and increased to 10 mm/a in the eastern segment.Combining with the hypocentral depth profile,we speculate the middle-eastern segments is a seismic gap,and have a strong seismic risk.Therefore,we should pay more attention to it.