Fine relocation, mechanism, and tectonic indications of middle-small earthquakes in the Central Tibetan Plateau

作     者：YuLan Li BaoShan Wang RiZheng He HongWei Zheng JiangYong Yan Yao Li 

作者机构：Key Laboratory of Earthquake Observation and Geophysical Imaging Institute of GeophysicsChina Earthquake Administration Key Laboratory of Geodynamics of the Department of Natural Resources Chinese Academy of Geological Sciences Institute of Geology Chinese Academy of Geological Sciences 

出 版 物：《Earth and Planetary Physics》 (地球与行星物理（英文版）)

年 卷 期：2018年第2卷第5期

页      面：406-419页

学科分类：070802[理学-空间物理学] 07[理学] 0708[理学-地球物理学] 

基　　金：supported by the National Key R/D Project (2016YFC0600301, 2016YFE0109300) the National Natural Science Foundation of China (41574086, 41761134094) China Geological Survey project (DD20160022-05) 

主　　题：relocation focal mechanism solution compression Gêladaindong ground surface response 

摘      要：The medium-small earthquakes that occurred in the middle part of Tibetan Plateau(32°N–36°N, 90°E–93°E) from August 2016 to June 2017 were relocated using the absolute earthquake location method Hypo2000. Compared to the reports of Chinese Seismological Networks, our relocation results are more clustered on the whole, the horizontal location differences exceed 10 km, and the focal depths are concentrated in 0–8 km, which indicates that the upper crust inside the Tibetan Plateau is tectonically active. In June2017 altogether eight earthquakes above magnitude 3.0 took place; their relocated epicenters are concentrated around Gê*** relocation results of M3.0 small earthquakes also showed obvious differences. Therefore, we used the CAP method to invert for the focal mechanisms of the M ≥3.0 earthquakes; results generally tally with the surface geological structures, indicating that the Tibetan Plateau is still under the strong compressional force from the India Plate. Among them the eight earthquakes that occurred near Gêladaindong in June 2017 are all of normal fault type or with some strike-slip at the same time; based on previous research results we conjecture that these events are intense shallow crust responses to deep crust-mantle activities.