COSEISMIC SURFACE RUPTURES AND SEISMOGENIC MUJI FAULT OF THE 25 NOVEMBER 2016 ARKETAO MW6.6 EARTHQUAKE IN NORTHERN PAMIR |
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Authors: | CHEN Jie LI Tao SUN Jian-bao FANG Li-hua YAO Yuan Li Yue-hua WANG Hao-ran FU Bo |
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Institution: | 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;
2. School of Earth Sciences and Engineering, Sun Yat-Sen University, Guangzhou 510275, China;
3. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China;
3. Earthquake Administration of the Xinjiang Uygur Autonomous Region, Urumqi 830000, China |
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Abstract: | The MW6.6 Arketao earthquake,which occurred at 14:24:30 UTC 25 November 2016 was the largest earthquake to strike the sparsely inhabited Muji Basin of the Kongur extension system in the eastern Pamir since the M 7 1895 Tashkurgan earthquake.The preliminary field work,sentinel-1A radar interferometry,and relocated hypocenters of earthquake sequences show that the earthquake consists of at least two sub-events and ruptured at least 77km long of the active Muji dextral-slip fault,and the rupture from this right-lateral earthquake propagated mostly unilaterally to the east and up-dip.Tectonic surface rupture with dextral slip of up to 20cm was observed on two tens-meter long segments near the CENC epicenter and 32.6km to the east along the Muji Fault,the later was along a previously existing strand of the Holocene Muji fault scarps.Focal mechanisms are consistent with right-lateral motion along a plane striking 107°,dipping 76° to the south,with a rake of 174°.This plane is compatible with the observed tectonic surface rupture.More than 388 aftershocks were detected and located using a double-difference technique.The mainshock is relocated at the Muji Fault with a depth of 9.3km.The relocated hypocenters of the 2016 Arketao earthquake sequence showed a more than 85km long,less than 8km wide,and 5~13km deep,NWW trending streak of seismicity to the south of the Muji Fault.The focal mechanism and mapping of the surface rupture helped to document the south-dipping fault plane of the mainshock.The listric Muji Fault is outlined by the well-resolved south-dipping streak of seismicity.The 2016 Arketao MW6.6 and 2015 Murghob MW7.2 earthquakes highlight the importance role of strike-slip faulting in accommodating both east-west extensional and north-south compressional forces in the Pamir interior,and demonstrate that the present-day stress and deformation patterns in the northern Pamir plateau are dominant by east-west extension in the shallow upper crust. |
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Keywords: | Pamir Arketao MW6 6 earthquake surface rupture InSAR aftershock Muji fault |
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