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The large deep-seated deposit landslides are well-developed and exhibit significant deformation activity in the upper Jinsha River, Tibetan Plateau. However, the understanding of their complex deformation mechanism remains limited. As a representative case, the Xiaomojiu landslide is selected to reveal the deformation mechanism of large deep-seated deposit landslides in the upper Jinsha River. The landslide volume is estimated to be approximately 5.04-7.56 x 107 m3, and it can be divided into four distinct zones in plane: source zone, right flank scarp, accumulation zone, and front collapse zone. The buried depth of the deep sliding surface in the middle and front of the landslide is approximately 40-50 m, with several secondary sliding surfaces developed within the landslide deposits. The long-term surface deformation predominantly occurs in the middle and left front of the landslide, which is still in the stage with constant-rate deformation at present. The longitudinal gradient, erosion rate, and steepness index of the Jinsha River are significant factors that contribute to long-term intense river erosion, which is an important factor for the long-term creep deformation of the landslide. Following the Baige landslide in 2018, both the deformation range and rate of the Xiaomojiu landslide increased significantly, indicating that the short-term extreme river erosion events, including barrier lakes and outburst floods, are critical factors contributing to the exacerbated short-term landslide deformation. The free faces of the deeply incised gullies have altered the development directions of tensile fissures and fall scarps on both sides, indicating that these deeply incised gullies caused by precipitation-induced surface erosion have exacerbated the deformation and failure of rock and soil masses. In summary, it can be inferred that the potential instability mode of the Xiaomojiu landslide is characterized as a front-traction and rear-tension type under the combined action of long-term intense river erosion, short-term extreme river erosion, and precipitation-induced surface erosion. The research findings provide new insights into the deformation mechanism of large deep-seated deposit landslide in alpine canyon areas.

来源平台：LANDSLIDES