A 15-year history of repeated ice-rock avalanches from a single source area in the Qinghai-Tibet Plateau

Abstract

Four repeated ice-rock avalanches occurred in the Amney Machen Mountains between 2004 and 2019, exhibiting both spatial and temporal characteristics of a recurring disaster chain. These events serve as notable examples of large-scale ice-rock avalanche chain disasters in the Qinghai-Tibet Plateau. Integrating multi-source data including remote sensing imaging, meteorological records, and glacier field observations, the geological and climatic characteristics of recurring ice-rock avalanches were characterized. A comprehensive study of the dynamic glacial changes in the region using multiple approaches, including offset-tracking and support vector machine classification, reveals the underlying triggering mechanisms and spatio-temporal evolution of the ice-rock avalanches. To investigate the possible impact of seismic events on the occurrence of repeated ice-rock avalanches, we performed a time-series analysis of the avalanche-prone mass to assess disaster risk. The results suggest that ice-rock avalanches in Amney Machen are caused by long-term climate warming, short-term meteorological fluctuations, glacier retreats, and patterns of ablation rather than earthquakes. Regional warming has culminated in glacier melt and de-buttressing, while freeze–thaw cycles have caused the propagation of stress crevasses and the deterioration of the ice-rock masses. Meltwater and rainfall introduce external driving forces to the ice-rock system, acting to lubricate and soften the bedrock and accelerate glacier sliding. The glacier’s ablation pattern, characterized by significant thinning at its lower part and slight thinning or even localized thickening at the top, has further heightened the hazard of glacial disasters. Our findings reveal the characteristics, triggering mechanisms, and spatio-temporal evolution of typical ice-rock avalanches, providing insights for monitoring and preventing glacial disasters throughout the Qinghai-Tibet Plateau.