Editing Vatnajökull (section)

==Volcanoes==
Under the ice cap, as under many of the [[glacier]]s of Iceland, there are several [[List of volcanoes in Iceland|volcanoes]].<ref name=":1" /> Eruptions from these volcanoes have led to the development of large pockets of water beneath the ice, which may burst the weakened ice and cause a [[jökulhlaup]] ([[glacial lake outburst flood]]).<ref name=":1" /> During the [[Last glacial period|last ice age]], numerous volcanic eruptions occurred under Vatnajökull, creating many [[subglacial eruption]]s.<ref name="readersnatural2">{{Cite book|title=Natural Wonders of the World|url=https://archive.org/details/naturalwondersof00sche|url-access=registration|publisher=Reader's Digest Association, Inc|year=1980|isbn=0-89577-087-3|editor-last=Scheffel|editor-first=Richard L.|location=United States of America|pages=[https://archive.org/details/naturalwondersof00sche/page/394 394]-395|editor-last2=Wernet|editor-first2=Susan J.}}</ref>

In more modern times, the volcanoes continue to erupt beneath the glaciers, resulting in many documented floods. One jökulhlaup in 1934 caused the release of {{Cvt|15|km3|cumi|frac=4}} of water over the course of several days.<ref name="readersnatural2" /> The volcanic lake [[Grímsvötn]] was the source of a large jökulhlaup in 1996.<ref>{{Cite web|url=http://earthice.hi.is/gjalp_eruption_vatnajokull_309_1310_1996|title=The Gjálp eruption in Vatnajökull|publisher=Institute of Earth Sciences, [[University of Iceland]]}}</ref> There was also a considerable but short-lived eruption of the volcano under these lakes at the beginning of November 2004.<ref name=":2">{{Cite web|url=https://earthice.hi.is/grimsvotn_eruption_2011|title=Grímsvötn eruption 2011|publisher=Institute of Earth Sciences, [[University of Iceland]]}}</ref> On 21 May 2011 a volcanic eruption started in Grímsvötn in Vatnajökull National Park at around 19:00.<ref name=":2" /> The plume reached up to {{convert|17|km|ft|abbr=on}}.<ref name=":2" />