Spatiotemporal deformation analysis of the reactivated Qingpo colluvium landslide in Wenchuan using multi-source time-series InSAR

The Qingpo landslide, located in Wenchuan County, Sichuan Province, China, poses a significant threat to the National Highway G213 and nearby residents. In this study, we applied the SBAS-InSAR technique to multi-source SAR datasets – including C-band ENVISAT ASAR (descending, 2008–2011), L-band ALOS-1 PALSAR (ascending, 2009–2011), and C-band Sentinel-1 (ascending and descending, 2014–2020) – to map the spatiotemporal evolution of surface deformation during the Qingpo landslide. By combining ascending and descending Sentinel-1 data, we decomposed the line-of-sight deformation into east–west and vertical components, revealing a typical push-type failure mechanism with rear-edge subsidence and frontal uplift. Three stages of deformation were identified: slow creep (2014–2016), accelerated deformation (2016–2018), and continued progressive failure (2018–2020). Deformation was found to be correlated with seasonal rainfall and leakage from irrigation reservoirs within the landslide body. The integration of multi-platform, multi-orbit SAR data with geomechanical analysis provides new insights into the kinematics of this reactivated ancient landslide.