part of Vatnajökull. In the whole, many cauldrons are to be found within Vatnajökull glacier (8,100 km in 2015), the largest of which in the western part of the ice cap are the Skaftá cauldrons. These ice cauldrons "are created by melting at subglacial geothermal areas". The meltwater accumulates in lakes "under the cauldrons until it drains every 2–3 years in a jökulhlaup" of normally up to 2,000 m/sec. An unusually big outburst flood (jökulhlaup) was recorded in 2015. The eastern Skaftá cauldron had accumulated meltwater in this case during around 5 years. It was discharged down the Skaftá river in September 2015 with a peak of 3,000 m/sec or even more. The cauldron then partially collapsed and formed a depression of up to 110 m deep in its center and a max. width of 2.7 km. Katla Famous examples from Iceland are the ice cauldrons within the Katla caldera. Katla is an important caldera and central volcano situated under the Mýrdalsjökull glacier cap in the southern part of Iceland's East Volcanic Zone. 150–200 eruptions during Holocene have been attributed to her, and 17 of these happened since Settlement of Iceland in the 8th century. Most of the eruptions had their origin in the ice covered caldera. The last contested big eruption took place in 1918 and initiated a jökulhlaup with an estimated peak discharge of 300,000 m/sec. Within the caldera 12–17 ice cauldrons are supra- and inglacial manifestations of a near-surface magmatic storage system. K. Scharrer even explains that "twenty permanent and 4 semi-permanent ice cauldrons could be identified on the surface of Mýrdalsjökull indicating geothermally active areas in the underlying caldera." They have a depth of 10–40 m and a width of 0.6–1.6 km. In 1955, 1999 and 2011 small to medium-sized jökulhlaup originated from some new ice cauldrons. It is still subject of discussion if they were eruption caused or initiated by heating up of the geothermal areas under these cauldrons."The geothermal heat output is in the order of a few hundred megawatt." Ice cauldrons in other environments Ice cauldrons of course do not form only in Iceland, but also at many other places where there is subglacial volcanic activity, e.g. in Alaska (Mount Redoubt, Mount Spurr). Ice cauldrons and volcano monitoring As deepening and widening of the ice cauldrons e.g. at Katla volcano, and esp. in combination with increased seismic activity at the sites, are interpreted