Ice cauldrons are ice formations within glaciers that cover some subglacial volcanoes. They can have circular to oblong forms. Their surface areas reach from some meters (as indentations or holes in the ice) to up to 1 or more kilometers (as bowl shaped depressions). Their existence is connected to ice-volcano interaction in two possible ways: They can be formed in the course of a subglacial eruption or on top of a continuously active subglacial high temperature geothermal area. In both cases, a jökulhlaup may be produced in connection with them. Formation and continued existence of ice cauldrons Ice cauldrons and subglacial eruptions When an eruption takes place under a bigger glacier, e.g. an ice cap, it normally begins with an effusive stage. The heat forms an ice cave and pillow lava is produced. After some time, the eruption has reached a stage where the pressure drops within the ice vault and the eruption style changes to become explosive. Hyaloclastite is produced and the heat is transferred to the meltwater. „At this stage, the surface ice begins to act brittle and creates concentric fractures that cave in towards the meltwater reservoir. This is referred to as the ice cauldron." When the eruption continues, “the meltwater reservoir becomes so large that the ice cauldron collapses inward towards the edifice, exposing the meltwater reservoir and allowing the breach of both the reservoir and the explosive lava, releasing plumes of gasses and jets of hyaloclastites “. The ice cauldron can develop further into an ice canyon, as was the case during the 1996 Gjálp eruption. It can continue to exist after the meltwater has left the eruption site and the eruption is terminated. But in most cases, ice flow will fill up the ice cauldron again and make it disappear as soon as the eruption products have cooled down enough. Ice cauldrons on top of subglacial geothermal areas Another case are ice cauldrons situated on top of geothermal areas. "(…) hydrothermal systems are created that bring heat up from a magma body, continuously melting ice into water that may be stored at the glacier bed until it breaks out in jökulhlaups." Many examples for a decades long existence of such ice cauldrons are to be found in Iceland. Ice cauldrons around the world Examples from Iceland Skaftárkatlar (Skaftá cauldrons) These are two depressions in the ice cover above two subglacial lakes in the southwestern