Editing Askja (section)

== Geography ==
The Askja central volcano is {{cvt|20|km}} in diameter and is associated with the '''Askja volcanic system''' which has a {{cvt|190|km}} long fissure swarm that extends north from beneath the [[Vatnajökull]] glacier towards the north coast of Iceland.<ref name =CIV>{{cite web|url =https://icelandicvolcanoes.is/?volcano=ASK|title= Catalogue of Icelandic Volcanoes:Askja Alternative name: Askja-Dyngjufjöll, Askja-Hrúthálsar|first1 =Thor|last1 =Thordarson|first2 = Margaret|last2=Hartley|year =2021}}</ref> The Hrúthálsar area which is {{cvt|20|-|30|km}} to the north-east is now usually regarded as part of the system.<ref name =CIV/>

The outer caldera of Askja, representing a prehistoric eruption, is about {{cvt|50|km2}} in area, and there is evidence of other later caldera-forming events within it. These include the main summit caldera, that is about {{cvt|8|km}} in diameter, to its north-east the {{cvt|4|km}} diameter Kollur caldera, and the 1875 Öskjuvatn caldera with a diameter of about {{cvt|5|km}}.  The main crater floor lies at about {{cvt|1100|m|ft}}.<ref name =CIV/>

The central volcano region is only accessible for a few months of the year. Being situated in the [[rain shadow]] to the northeast of the [[Vatnajökull]] [[glacier]], the area receives only about {{cvt|450|mm|in}} of [[rain]]fall annually.

=== NASA ===
The area was used by [[NASA]] during training for the [[Apollo program]] to prepare astronauts for the lunar missions. Their main objective in Askja was to study geology. [[The Astronaut Monument]] in [[Húsavík]] lists the 32 astronauts who participated.<ref>{{Cite web|title = Apollo astronauts revisit training area in Iceland and explore a new lava flow - The Exploration Museum|url = http://www.explorationmuseum.com/2015/07/astronauts-revisit-training-area-and-explore-a-new-lava-flow/|website = www.explorationmuseum.com|access-date = 2015-08-09|archive-date = 2019-04-02|archive-url = https://web.archive.org/web/20190402042808/http://www.explorationmuseum.com/2015/07/astronauts-revisit-training-area-and-explore-a-new-lava-flow/|url-status = dead}}</ref><ref>{{Cite web|title = Barnabörn Armstrongs afhjúpuðu minnisvarða|url = http://www.mbl.is/frettir/innlent/2015/07/15/barnaborn_armstrongs_afhjupudu_minnisvarda/|access-date = 2015-08-09}}</ref>