- 1Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China (sxiaoai@connect.ust.hk)
- 2Department of Geotechnical Engineering, College of Civil Engineering, Tongji University, Shanghai, China
- 3Department of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, China
On December 18, 2023, a Ms 6.2 earthquake struck Jishishan County, Gansu Province, China, triggering a catastrophic loess flowslide in Zhongchuan Town, Qinghai Province. The flowslide covered a total area of 508,200 m² and initiated a hazard chain that eroded an 8-meter-high earth dam, destroyed 51 residential buildings, and caused over 20 fatalities. Notably, the flowslide showed extraordinary mobility, traveling 3160 meters across gentle terrain with an overall travel angle of just 1.5°, surpassing the mobility of other known landslide types. To explore the underlying mechanisms behind its hypermobility, we conducted field surveys, UAV-based photogrammetry, LiDAR analysis, and numerical simulations. Three primary causes of its hypermobility were identified: (1) liquefaction of water-saturated silty loess, induced by irrigation activities and seismic loading, which significantly reduced basal resistance; (2) the macro-pore structure of loess, promoting the fluidization of displaced material; and (3) channelized topography combined with a low-friction icy channel bed, which enhanced flow momentum. Numerical simulations further demonstrated that variations in degrees of liquefaction strongly influenced the flowslide’s mobility and destructive potential.
How to cite: Xiao, S., Zhang, L., He, J., Peng, M., Jiang, R., and Lu, W.: A Highly Mobile Loess Landslide Induced by the 2023 Ms 6.2 Jishishan Earthquake in Northwest China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6581, https://doi.org/10.5194/egusphere-egu25-6581, 2025.
