Active formation of ‘chaos terrain’ over shallow subsurface water on Europa

The great lakes of Europa The Galileo spacecraft revealed a number of 'chaos' regions on Jupiter's moon Europa, where the surface terrain appears to have been disrupted from below. In many places, the surface contains sharp-edged blocks or rafts of ice that have at some point been flipped or rotated. Some characteristics of these regions have been hard to explain, such as the fact that the archetypal Conamara Chaos stands above its surroundings and contains matrix domes. Schmidt et al. apply lessons learned from analogous processes within Earth's subglacial volcanoes and ice shelves to an analysis of archival data that suggests chaos terrain forms above liquid water 'lenses' that are perched only 3 kilometres deep within the ice shell. The data suggest that ice–water interactions and freeze-out give rise to the varied morphology of chaos terrains, implying that more water is involved than has been previously appreciated — for instance, the sunken topography of Thera Macula, a large chaos area, may indicate that Europa is actively resurfacing over a lens comparable in volume to North America's Great Lakes.