Failure mechanism and dynamic process of the Jinping high-position and long-runout landslide in the Wumeng mountainous area, China, on 8th February 2025

The Wumeng Mountain area is characterized by complex geological conditions and is prone to high-position, long-runout landslide–debris flow chains. This study integrates field investigation, remote sensing interpretation, InSAR monitoring, laboratory tests, and numerical simulation to reveal the deformation evolution, genetic mechanism, and kinematic process of the landslide. The results show that the controlling factors can be stratified into two levels. At the geological level, the anti-dip fragmented rock mass with interbedded hard and soft strata constitutes the primary internal cause of slope instability, while the steep-upper and gentle-lower topography provides the morphological precondition for the transformation of the sliding mass into a debris flow. At the rainfall level, continuous infiltration significantly reduces slope stability and acts as the key triggering factor. Initial deformation appeared in 2014 and accelerated continuously after 2020, eventually leading to failure, with unstable rock masses still remaining at the rear scarp. Simulation results show that the entire process lasts about 50 s, with a maximum velocity of 48 m/s and a maximum accumulation thickness of 23 m, accompanied by progressive fragmentation of the rock mass. Such landslides share similar disaster-prone characteristics, which can provide references for the early identification of potential landslide hazards in the region.