Distribution law and susceptibility of geohazards across a gradient belt of the Western Sichuan Plateau

Across a gradient belt of the Western Sichuan Plateau, geohazards have seriously limited economic and social development. According to incomplete statistics, 15,673 geohazards have been recorded in the study area. In order to mitigate the threat of geohazards to human engineering activities in the region, an overall understanding of the distribution pattern of geohazards and susceptibility assessment are necessary. In this paper, a gradient belt of the Western Sichuan Plateau and its zoning criteria were defined. Subsequently, on the basis of relief amplitude, distance to faults, rainfall, and human activities, three indicators of endogenic process were introduced: Bouguer gravity anomaly gradient, vertical deformation gradient, and horizontal deformation gradient. Thereafter, the distribution patterns of geohazards were investigated through mathematical statistics and ArcGIS software. By randomly selecting 10,449 hazards, a geohazard susceptibility map was generated using the Information Value (IV) model. Finally, the IV model was validated against 5224 hazards using the Area Under Curve (AUC) method. The results show that 47.6% of the geohazards were distributed in the zone of steep slope. Geohazards showed strong responses to distance to faults, human activities, and annual rainfall. The distribution of geohazards in the gradient belt of the Western Sichuan Plateau is more sensitive to vertical internal dynamics factors (such as vertical deformation gradient and Bouguer gravity anomaly gradient) without any apparent sensitivity to horizontal internal dynamics factors. The areas of high and very-high risk account for up to 32.22%, mainly distributed in the Longmenshan and Anning River faults. According to the AUC plot, the success rate of the IV model for generating the susceptibility map is 76%. This susceptibility map and geohazard distribution pattern can provide a reference for geological disaster monitoring, preparation of post-disaster emergency measures, and town planning. © Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2024.