Duoqing Co is located in the nearly South- North Pagri graben, which belongs to the southern part of Yadong-Gulu rift in Tibet. However, the water in the lake disappeared in half to one year (in the period from November, 2015 to April, 2016) after the Nepal earthquake. We think that the phenomenon was not caused by climate change and human activity based on the past meteorological and remote sensing data. And there may be buried fault with the direction of NNE at the east boundary of Duoqing Co under the remote sensing interpretation and surface investigation. We also found plenty of nearly NE extensional cracks on the dried-up lake, which may have been formed by the creep of the lake boundary fault zone. And we predicted that the water leaked from the fractured group likely. Under the investigation and tectonic analysis, we suggest that the stress of the Bhutan-Sikkim earthquake locking region located in Main Himalaya Thrust fault zone increased from slow to rapid causing elastic strain locally after 2015 Nepal earthquake. Therefore, the underground of Pagri graben generated nearly EW extension and expansion leading to resulting that the water flow into the water-beating stratum and lake drying up in a short time. Then, the strain relaxation and the fractures close, which caused the water recovery under the ground of rainy season of the plateau. If so, the abnormal phenomena are likely to be response to the further enhancement of stress-strain of Buhtan-Sikkim Himalayan segment. This would also imply that the crust has a sensitive or critical state and indicate that stress-strain hardening is a seismic precursor in the Main Himalaya thrust fault zone before a possibly huge earthquake. Further, the abnormal phenomenon on the surface in the Bhutan – Sikkim locking region, Himalaya Thrust fault zone, is worth paying attention to and being vigilant, especially against the background of the active phase of the large earthquake in the main thrust belt of Himalaya.
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