Editing Caldera (section)

==Caldera formation==
[[File:Origin of volcanic caldera via analogue model.gif|thumb|Animation of an analogue experiment showing the origin of a mock volcanic caldera in box filled with flour]]
[[File:Toba zoom.jpg|thumb|[[Landsat]] image of [[Lake Toba]], on the island of [[Sumatra]], [[Indonesia]] (100 km/62 mi long and 30&nbsp;km/19 mi wide, one of the world's largest calderas). A [[resurgent dome]] formed the island of [[Samosir]].]]
[[File:Cagar Alam Rawa Danau Caldera.png|thumb|Topographic map of Cagar Alam Rawa Danau Caldera in Indonesia]]

A collapse is triggered by the emptying of the [[magma chamber]] beneath the volcano, sometimes as the result of a large explosive [[volcano|volcanic eruption]] (see [[1815 eruption of Mount Tambora|Tambora]]<ref>{{cite web |last1=Greshko |first1=Michael |title=201 Years Ago, This Volcano Caused a Climate Catastrophe |url=https://www.nationalgeographic.com/news/2016/04/160408-tambora-eruption-volcano-anniversary-indonesia-science/ |archive-url=https://web.archive.org/web/20190926233008/https://www.nationalgeographic.com/news/2016/04/160408-tambora-eruption-volcano-anniversary-indonesia-science/ |url-status=dead |archive-date=26 September 2019 |website=National Geographic |date=8 April 2016 |access-date=2 September 2020}}</ref> in 1815), but also during effusive eruptions on the flanks of a volcano (see [[Piton de la Fournaise]] in 2007)<ref>{{Cite gvp|vn=233020|title=Piton de la Fournaise|date=2019}}</ref> or in a connected fissure system (see [[Bárðarbunga]] in 2014–2015). If enough [[magma]] is ejected, the emptied chamber is unable to support the weight of the volcanic edifice above it. A roughly circular [[Fracture (geology)|fracture]], the "ring fault", develops around the edge of the chamber. Ring fractures serve as feeders for fault [[intrusion]]s, which are also known as [[ring dike]]s.<ref name="philpotts-ague-2009">{{cite book |last1=Philpotts |first1=Anthony R. |last2=Ague |first2=Jay J. |title=Principles of igneous and metamorphic petrology |date=2009 |publisher=Cambridge University Press |location=Cambridge, UK |isbn=9780521880060 |edition=2nd}}</ref>{{rp|86–89}} Secondary volcanic vents may form above the ring fracture.<ref>{{cite book|last1=Dethier|first1=David P.|last2=Kampf|first2=Stephanie K.|title=Geology of the Jemez Region II|date=2007|publisher=Ne Mexico Geological Society|page=499 p|url=http://nmgs.nmt.edu/publications/guidebooks/58|access-date=6 November 2015|archive-date=17 October 2015|archive-url=https://web.archive.org/web/20151017020924/http://nmgs.nmt.edu/publications/guidebooks/58/|url-status=dead}}</ref> As the magma chamber empties, the center of the volcano within the ring fracture begins to collapse. The collapse may occur as the result of a single cataclysmic eruption, or it may occur in stages as the result of a series of eruptions. The total area that collapses may be hundreds of square kilometers.<ref name="cole-etal-2005"/>