Controls on Basal Adhesion of Ice on Bedrock in Glacier Detachment Events

The increasing frequency of ice avalanches caused by the sudden falling of hanging ice from steep cliffs in cryospheric zones has made them a significant form of glacial disaster. The process is primarily governed by the adhesive behavior of ice to bedrock—a mechanism fundamentally distinct from the frictional sliding observed in low-elevation glacier surges. Yet research on the adhesive properties of the ice-rock interface remains limited. In this study, a novel centrifugal testing method was employed to investigate the adhesion strength of the glacier-bedrock interface. Experimental results indicate that ambient temperature, interface morphology, and basal rock lithology exert a primary control on ice-rock adhesion strength. The ice-rock adhesion strength exhibits a strong linear relationship with ambient temperature, with tensile strength consistently surpassing shear strength. Interfacial roughness generally enhances ice adhesion to bedrock, but excessive roughness can lead to strength saturation or even reduction. Cryo-electron microscopy observation reveals that this phenomenon is attributable to air pocket formed at irregular contacts under high surface roughness conditions. Lithological controls produce striking variations in ice adhesion strength—up to nearly two-fold differences across varying rock types. The observed micro-rhizoidal ice connections between the ice and bedrock suggests an ‘ice root effect’ as the underlying mechanism for the notably enhanced ice adhesion strength to porous rocks. Based on the experimental data, an adhesion strength criterion for the glacier-bedrock interface was proposed. This study establishes a foundation for evaluating and predicting glacier stability in high-alpine environments.