Frost cracking dictated landslide distribution in response to temperature change since Last Glacial Maximum across the Eastern Qilian Mountains

Abstract

AbstractTemperature‐dependent frost cracking is a major weathering process that dominates sediment supply and hillslope erosion by reducing shear strength and conditioning slopes to be more failure‐prone in cold mountain regions. Landslides are a common erosional process in such landscapes. The linkage between these two processes has been proposed but many of the mechanisms remain to be investigated. In this study we compile a landslide inventory in the Eastern Qilian Mountains including 2482 rockfalls and 5373 elongate transport zone footprints. We use a widely accepted frost cracking model to explore this weathering process as a mechanism of paleoclimate control on the modern landslide distribution. The results show that landslides concentrate in a narrow altitudinal range and that this elevation dependence varies with slope aspect. Based on the paleoclimate record, we calculate the time‐averaged frost cracking intensity (Fci) since Last Glacial Maximum (LGM) and adopt different parameters for two slope aspects. We find that time averaged Fci is a good predictor of the landslide elevation distribution for both aspects. We then introduce two slope‐based landslide initiation and runout models (i.e., SHALRUN and FCIRUN) to examine the relative roles of slope versus temperature in determining the landslide probability in space. The FCIRUN model, which incorporates Fci as a measure of sediment supply, consistently outperforms the SHALRUN model. This result suggests that frost cracking determines the pattern of landslide initiation, although topography still controls their runout path. Our study highlights the potential of introducing Fci into slope‐based landslide prediction models to improve model skill in identifying hazardous areas (e.g., rockfall) across weathering‐limited landscapes like the Qilian Mountains.