Failure mechanism and kinetic feature of a high locality landslide at Qingliu Village, Li County, China, 2020

On December 4, 2020, a massive high-locality landslide occurred at Qingliu Village, Li County, Sichuan Province, China (UTC + 8). This event resulted in a landslide deposit of approximately 34.8 × 10⁴ m³, causing the destruction of two roads and several houses on the hillslope and blocking a downstream river. Extensive field investigations, UAV photography, borehole drilling, and GNSS monitoring were conducted after the landslide. Additionally, a PFC3D numerical simulation was used to reproduce the movement of the landslide after calibrating its meso-strength parameters. Based on the motion and deposit characteristics, the landslide is divided into a major sliding zone (comprising the source zone, impact-shoveling zone, and deposition zone) and a landslide-affected zone. The primary triggering factor for the Qingliu landslide is the slope mass damage caused by frequent preceding earthquakes. On the other side, the direct triggers are continuous rainfall and upslope meltwater, which increased the weight and further weakened the strength of the slope mass. The landslide initiation involves the formation of a tensile crack in the major sliding zones, followed by the shoveling of loose debris by the displaced landslide mass, and then termination with the striking at the slope foot and damming a river. This study offers valuable insights into the evolutionary processes of high-locality landslides.