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Abstract:
The borderland between China and Myanmar is characterized by complex tectonics and heavy seismic hazard, but its present-day crustal deformation pattern is still contentious. We have processed all the data of regional GNSS networks from 1998 to 2020 for this region and further derived strain rate fields. The results show that Myanmar arc moves towards the Qinghai Tibet Plateau in the NNE direction at a velocity of ~30mm/yr. The shear strain accumulation in this zone is prominent, with east-west compression at outer flank of the arc, and nearly south-north compression at its interior. The Sagaing fault is characterized by heterogeneous kinematics with higher principal strain rate and shear strain rate.Sichuan Yunnan block is rotating remarkably clockwise around the eastern Himalayan syntaxis. The Xiaojiang fault zone is experiencing sinistral strike slip. The central segment of Honghe fault has a lower strike slip rate, while the north and south segments have a relatively higher shear rate. The Dayingjiang fault in southwestern Yunnan shows east-west extension and sinistral strike slip. The Longling-Ruili fault is characterized by dextral strike slip and extension. The NE trending Nantinghe fault, Menglian fault and Jinghong-Daluo fault have lower shear rates, dominated by left-lateral strike- slip. The Lancang fault and Wuliangshan faults are characterized by a dextral strike slip, while the northwest trending Longling-Lancang fault zone shows dextral strike slip and tension. The study is significant to earthquake disaster assessment and understanding of the regional geodynamics of this region.
