Development and distribution characteristics of geological hazards and disaster-causing mechanism of typical landslide groups in Lanzhou

Lanzhou City is characterized by a complex geological environment and frequent geohazards, posing severe challenges to disaster prevention and mitigation. Based on the 1∶50000 geological hazard risk survey of Gansu province, this study systematically analyzes and summarizes the development characteristics and distribution patterns of geological hazards in the area. Using Interferometric Synthetic Aperture Radar (InSAR) technology, the spatiotemporal evolution of the Xujiawan landslide group is clarified, and combined with field geological surveys, its failure modes and disaster-causing mechanisms are revealed. The results indicate that: (1) Geological hazards in Lanzhou are dominated by potentially unstable slopes, debris flows, and landslides, collectively accounting for 86.0% of the total hazards; (2) Hazard sites in the main urban area are primarily distributed along both banks of the Yellow River and its tributaries, in zones with intensive geological structures, and in areas subject to strong engineering disturbance, especially in residential and industrial zones located at the front edges of high terraces along the Yellow River; (3) The Xujiawan landslide group exhibits a maximum annual deformation rate of 15.85 mm/year. Its development is controlled by intense neotectonic activity, with jointed and fractured rock masses providing a structural basis for slip surface formation. High-intensity earthquakes and concentrated rainfall further reduce the shear strength of the rock and soil mass; (4) Human engineering activities are key triggering factors for landslide disasters. Large-scale excavation at slope toes creates steep free surfaces, directly disrupting the original stress equilibrium, whereas irrigation and urban construction loading significantly increase pore water pressure and slope load. The research results of this study provide empirical evidence and scientific support for geohazard risk prevention and sustainable development in Lanzhou City.