Abstract:
The Gelongbu landslide is located on both banks of the Hutiao Gorge in the middle section of the Jishixia Canyon, in the upper reaches of the Yellow River. This region lies at the geomorphological transition zone between the Qinghai-Tibet Plateau and the Loess Plateau, where geological and geomorphological conditions are highly complex. In recent years, moderate to strong earthquakes have occurred frequently. In particular, following the 2023 Jishishan Ms 6.2 earthquake, seismic hazard and earthquake-induced landslide risks in this area have attracted increasing attention. In this study, high-precision Digital Elevation Models (DEMs) and orthophotos obtained through UAV aerial surveying were used to conduct a detailed analysis of the geometric characteristics of the Gelongbu landslide. FLAC3D numerical simulations were then performed to identify potential hazard zones under seismic loading. Combined with landslide dynamics theory and regional topographic–geomorphological features, the potential extent of landslide movement was further predicted and assessed. In addition, a hazard index method was adopted to quantitatively evaluate the risk of earthquake-induced landslides and collapses by calculating seismic stability under ground motions with different exceedance probabilities, and by estimating potential hazardous sectors and sliding distances. The results indicate that the eastern and western flanks of the Gelongbu landslide’s accumulation zone are relatively steep and are highly susceptible to failure when subjected to seismic intensities of VIII or higher. The calculated slope hazard index ranges from 12 to 18, corresponding to medium to high hazard levels. In the event of failure, the predicted sliding distances of the eastern and western flanks are approximately 238 m and 264 m, respectively. Material entering the Yellow River would potentially cause severe impacts on river-channel stability and downstream safety. This research provides important scientific guidance for the identification, monitoring, early warning, and mitigation of hazards associated with the Gelongbu landslide.