Abrupt eruptive instability of ice adhered to solid surfaces.

Violent ice fracture events often trigger rapid climatic or geomorphic changes, including Antarctic ice shelf collapse, glacial outbursts, and frost quakes. Existing models of sequential crack propagation inadequately explain the sudden, explosive nature observed in natural events. Here, we uncover a previously unidentified eruptive fracture of ice adhered to solid surfaces upon quasistatic cooling, which can even cause the underlying substrate fragmentation. This explosive ice instability depends on the threshold internal grain size of the ice. Above this threshold, fracture proceeds in a progressive, energy-dominated mode, whereas below it the ice undergoes an abrupt, strain-dominated fracture. We found that the apparent tensile strength of adhered ice ranges from 39 to 58 megapascals, over an order of magnitude higher than the typical value of ice (0.7 to 3.1 megapascals). This work provides a mechanistic framework for understanding and predicting abrupt cryospheric fracture events and points toward rational strategies for designing self-actuating deicing systems that exploit thermomechanical instabilities.