Heavy rainfall drives slow-moving landslide in Mazhe Village, Enshi to a catastrophic collapse on 21 July 2020

Following extremely heavy rainfall, a catastrophic landslide occurred in Mazhe Village, Enshi, China, on 21 July 2020. In this study, we use C-band Sentinel-1A Interferometric Synthetic Aperture Radar (InSAR) measurements and Sentinel-2 optical imagery to retrieve the ground deformation evolution before this landslide and the aftermath. Optical imagery reveals that part of the slope body collapsed completely, while the mean normalized difference vegetation of the stable part drops from 0.703 to 0.514. Time series InSAR results show that the central and western parts of the slope body area have already undergone slow moving over the past years, which exhibited apparent seasonal variations with maximum changes when the accumulated rainfall reached its peak during the revisit period. The correlation between slope deformation and rainfall in the rainy season has been increasing, reaching over − 0.8 in 2020. The total deformation rate of the rainy season has a significantly strong correlation with the total precipitation, and the correlation coefficients at the two monitoring points reach − 0.9995 and − 0.9446, respectively, and the average value of the slope reaches − 0.8523. Multiple heavy rainfall events with short intervals are more tend to cause greater deformation. In addition, through the time-series InSAR analysis of the whole Qingjiang River in Enshi, another three creeping landslides are detected, and all show a linear trend with remarkable fluctuations in summer.