Modelling ice island calving events with Finite Element Analysis

Ice islands, massive tabular icebergs, are known to fracture (calve) into fragments as they drift. One proposed calving mechanism occurs when a large protuberance, known as a ram, develops along the submerged edge of the ice island and induces a bending stress due to its buoyancy. To examine the relationship between rams and ice island fracture, polygons of ice islands derived from remote sensing imagery were used to create 3-D representations with synthesized rams. Associated stress and fractures were predicted using a Finite Element Analysis (FEA) and the results were compared to polygons of the actual fractured pieces. Modelled ice islands calve accurately when a synthesized ram is placed only along the edge that breaks off. An empirical model was developed to predict stress magnitude, which indicated the length of the ram, ram extent, and the ratio of ram volume to total ice volume play a central role in calving.