Spatial and size distributions of large landslides along the southeastern margin of the Tibetan Plateau: the case of the Liangshan area

Abstract

The Liangshan Yi Autonomous Prefecture (LS area) is a region with complex geological conditions located at the southeastern margin of the Tibetan Plateau and is renowned for its susceptibility to landslides. However, there is a lack of understanding of the distribution of landslides in the LS area. To address this gap, a comprehensive inventory of large landslides is first established on the basis of remote sensing and field investigations, followed by spatial analysis. The results reveal that the LS area hosts at least 2142 large landslides (volume ≥ 10⁶ m³), covering a total area and volume of 1758.2 km² and 91.3 km³, respectively. More landslides are concentrated in the Yalong River subbasin than in other subbasins. Landslides exhibit an obvious fault-controlling effect, with more than 91% occurring within 2 km of faults, and the landslide frequency decreases exponentially with increasing distance from faults. Areas with alternating soft and hard rock types are more susceptible to landslides than areas with other rock groups are. The landslide size increases exponentially with topographic relief. Frequent seismic activity has been identified as an important potential trigger. Owing to limited data, spatial and size analyses may be immature, necessitating further systematic research.