The monitoring of a large ancient landslide in Sichuan Province, China, using interferometric synthetic aperture radar technology and sensitivity analysis in potential landslide mass modeling

Using interferometric synthetic aperture radar (InSAR) technology and C-band Sentinel-1A data, this work examined the surface displacement of a large ancient landslide at Xuecheng town in Lixian County, Sichuan Province, China. Based on the MassMov2D model, the dynamic process and deposit thickness of the potentially unstable rock mass (deformation rate <−70 mm/yr) on this landslide body was numerically simulated. Combined with unmanned aerial vehicle data, the driving factors of this ancient landslide were analyzed. The InSAR results showed that the deformation rate in the middle part of the landslide body was the largest at −55 ∼ −80 mm/yr on average, while that of the upper part and the toe area was small at −5 ∼ −20 mm/yr. The simulation predicted that the unstable rock mass may collapse and form a barrier dam with a maximum thickness of approximately 16 m at Zagunao River in the future.