InSAR monitoring and analysis of landslide deformation after the earthquake in the Zhangmu Port, Tibet

The Zhangmu Port,located on the border between China and Nepal,is a national first-class land trading port and the largest border trade port in Tibet. After the Nepal earthquake in 2015, the Zhangmu port was closed due to multiple landslide disasters. In order to investigate the distribution and deformation of landslide disasters in the Zhangmu port area so as to serve regional disaster mitigation and prevention,the InSAR technology was used to process the satellite image data of Sentinel-1A and ALOS-2 covering the area,and by analyzing the annual average rate map of line-of-sight deformation,17 suspected landslides were delineated,and the time series deformation characteristics of 5 typical landslides were analyzed. From the distribution point of view,the landslides identified by monitoring are basically distributed along the left bank of the Boiqu River on the side of National Highway 318. InSAR survey results show that the landslides in the Zhangmu area affected by the earthquake are mostly distributed on the steep hills along the left bank of the Boiqu River. The ancient landslides on the section of Disigang to Youyi Bridge on the China-Nepal Highway have partially resurrected,and the Zhameila dangerous rock mass collapses and landslides are also developed in the urban area where residents live in Zhangmu Town.