Editing Askja (section)

== Eruptions ==
Most eruptions are small, basaltic and effusive.<ref name =CIV/>  There have been at least 175 eruptions from the Askja system in the last 7200 years.<ref name=Hartley2016/>

=== 1961 ===
The last eruption of Askja was between 26 October and 5 December 1961 near the northern rim of the caldera.<ref name=gvp/> It produced the {{cvt|0.1|km3}} [[basalt]]ic Vikrahraun lava flow and also near the caldera another local permafrost layer under the {{cvt|0.004|km3}} of tephra.<ref name=Shoemaker2024/><ref name =CIV/>

=== 1875 ===
Askja was virtually unknown until a large 17 hour [[Sub-plinian eruptions|subplinian eruption]] which started on March 28, 1875.<ref name=Büntgen2024>{{cite journal|last1 =Büntgen|first1 =U.|last2 =Eggertsson|first2 =O.|last3 =Oppenheimer|first3 =C.|year =2024|title= Braided motivations for Iceland’s first wave of mass emigration to North America after the 1875 Askja eruption|journal =Regional Environmental Change|volume =24|issue =2|pages =48|doi =10.1007/s10113-024-02215-6|bibcode =2024REnvC..24...48B|doi-access=free}}</ref> The volcanic system had been active since 1 January 1875.<ref name=gvp/> This was followed by the devastating [[rhyolitic]] phreatoplinian explosion on March 29, 1875,<ref name =CIV/><ref>{{Cite journal |last1=Hartley |first1=Margaret E. |last2=Thordarson |first2=Thor |date=2013-07-29 |title=The 1874-1876 volcano-tectonic episode at Askja, North Iceland: Lateral flow revisited |journal=Geochemistry, Geophysics, Geosystems |volume=14 |issue=7 |pages=2286–2309 |doi=10.1002/ggge.20151 |bibcode=2013GGG....14.2286H |s2cid=53587010 |issn=1525-2027|doi-access=free }}</ref> which erupted {{cvt|0.33|km3}} [[dense-rock equivalent]].<ref name=Shoemaker2024>{{cite journal|last1 =Shoemaker|first1 =E.S.|last2 =Baker|first2 =D.M.H.|last3 =Richardson|first3 =J.A.|last4 =Carter|first4 =L.M.|last5 = Scheidt|first5 =S.P.|last6 =Whelley|first6 =P.L.|last7 =Young|first7 =K.E.|year =2024|title =Mapping ice buried by the 1875 and 1961 tephra of Askja Volcano, Northern Iceland using ground‐penetrating radar: Implications for Askja Caldera as a geophysical testbed for in situ resource utilization|journal =Journal of Geophysical Research: Planets|volume =129|issue =4|pages =e2023JE007834|doi =10.1029/2023JE007834|doi-access =free}}</ref>  The eruption finished on 17 October 1875.<ref name=gvp/> Locally around the caldera this ash fall on snow cover has resulted in the formation of a layer of permafrost ice.<ref name=Shoemaker2024/> Especially in the [[Eastfjords]] of Iceland, the ashfall was heavy enough to poison the land and kill livestock. Ash more than 1&nbsp;cm in thickness covered {{cvt|5000|km2}} and the total population in Iceland of sheep declined by 2% and cattle by 6.2% between 1874 and 1876.<ref name=Büntgen2024/> At least 16 farms were abandoned in 1876.<ref name=Büntgen2024/> Ash, or [[tephra]] from this eruption was wind-blown to [[Norway]], [[Sweden]], [[Germany]] and [[Poland]].<ref name=Shoemaker2024/> The eruption triggered a spike in [[emigration]] from Iceland but not as much as the Grímsvötn eruptions in the 1880s.<ref name=Büntgen2024/> Between February and October 1875 about {{cvt|60|km}} north of the Askja central volcano there were episodic [[basalt]]ic fissure eruptions, which erupted a comparable volume of magma to the explosive phase.<ref name=Büntgen2024/>  The eruption had no direct effect on regional or Northern Hemisphere vegetation and climate.<ref name=Büntgen2024/>

=== Early Holocene ===
Another less well-known large rhyolitic eruption, called Askja-S (Skolli), occurred in the early [[Holocene]], 10,824 ± 97 years {{abbr|BP|before 1950}}.<ref name =CIV/><ref name=Kearney2018>{{cite journal|last1 =Kearney|first1 =R.|last2 =Albert|first2 =P.G.|last3 =Staff|first3 =R.A.|last4 =Pál|first4 =I.|last5 =Veres|first5 =D.|last6 =Magyari|first6 =E.|last7 =Ramsey|first7 =C.B.|year =2018|title =Ultra-distal fine ash occurrences of the Icelandic Askja-S Plinian eruption deposits in Southern Carpathian lakes: New age constraints on a continental scale tephrostratigraphic marker|journal =Quaternary Science Reviews|volume =188|pages =174–182|doi =10.1016/j.quascirev.2018.03.035|bibcode =2018QSRv..188..174K}}</ref> [[Tephra]] from this eruption has been found in south-east [[Sweden]], [[Northern Ireland]] and north [[Norway]] and recently as far south as [[Romania]], which makes it one of the most far-travelled Icelandic tephras.<ref name=Kearney2018/>

=== Summary ===
{| class="wikitable sortable" width=50%
|+ List of Recent Eruptions
|-
! data-sort-type="number" width=95px | Start Date<ref name=gvp/>
! data-sort-type="number" width=95px | End Date<ref name=gvp/>
! width=70px | VEI<ref name=gvp/>
! Scale<ref name=CIV/>
! width=70px | Tephra volume<br/>(km<sup>3</sup>)<ref name=CIV/>
! class="unsortable"| Comments
|-
| align="center"| {{dts|October 26, 1961}}
| align="center"| {{dts|December 5, 1961}}
! style="background-color: #FD0;" | 2 
| align="center"| Small
| align="center"| 0.004
| 
|-
| align="center"| {{dts|December 19, 1938}}
| {{unknown}}
! style="background-color: #FD0;" | 2 
| align="center"| Small
| {{unknown}}
|
|-
| align="center"| {{dts|July 15, 1926}}
| align="center"| 
! style="background-color: #FD0;" | 2 
| align="center"| Moderate
| {{unknown}}
| Lasted about 45 days, Thorvaldshraun lava<ref name=Hartley2016>{{cite journal|last1 =Hartley|first1 =M.E.|last2 =Thordarson|first2 =T. |last3 =de Joux|first3 =A.|year =2016|title =Postglacial eruptive history of the Askja region, North Iceland|journal =Bulletin of Volcanology|volume =78|pages =1–18|doi =10.1007/s00445-016-1022-7|bibcode =2016BVol...78...28H|doi-access=free}}</ref>
|-
| align="center"| {{dts|1924}}
| {{unknown}}
! style="background-color: #FF0;" | 0 
| align="center"| Small
| {{unknown}}
| 
|-
| align="center"| {{dts|January 15, 1923}}
| align="center"|
! style="background-color: #FF0;" | 0
| align="center"| Small
| {{unknown}}
| Lasted about 45 days
|-
| align="center"| {{dts|November, 1922}}
| {{unknown}}
! style="background-color: #FF0;" | 0 
| align="center"| Small
| {{unknown}}
| 
|-
| align="center"| {{dts|March, 1921}}
| {{unknown}}
! style="background-color: #FF0;" | 0
| align="center"| Small
| {{unknown}}
| 
|-
| align="center"| {{dts|1919}}
| {{unknown}}
! style="background-color: #FD0;" | 2 
| align="center"| Small
| {{unknown}}
|
|-
| align="center"| {{dts|January 1, 1875}}
| align="center"| {{dts|October 17, 1875}}
! style="background-color: #F60;" | 5 
| align="center"| Major
| align="center"| 1.8
| Lava flows mainly south and north-east of Öskjuvatn caldera<ref name=Hartley2016/>
|-
| align="center"| {{dts|1797}}
| {{unknown}}
! style="background-color: #FF0;" | 0
| align="center"| Small
| {{unknown}}
| Lava flow on west caldera margin dated as to before 1873 by tephra studies<ref name=Hartley2016/>
|-
| align="center"| {{dts|1717}}
| {{unknown}}
| -
| align="center"| Small
| {{unknown}}
| Older than 1717 from tephra studies with lava flows on north-east caldera margin<ref name=Hartley2016/>
|-
| align="center"| {{dts|1619}}
| {{unknown}}
| -
| align="center"| Small
| {{unknown}}
| Older than 1619 from tephra studies with lava flows on north caldera margin<ref name=Hartley2016/>
|-
| align="center"| {{dts|1510}}
| {{unknown}}
| -
| align="center"| Small
| {{unknown}}
| Older than 1510 from tephra studies with lava flows to west caldera margin<ref name=Hartley2016/>
|-
| align="center"| {{dts|1477}}
| {{unknown}}
| -
| align="center"| Small
| {{unknown}}
| Older than 1477 from tephra studies with lava flows around caldera margin<ref name=Hartley2016/>
|-
| align="center"| {{dts|1300}}
| {{unknown}}
! style="background-color: #FE0;" | 1 
| align="center"| Small
| {{unknown}}
| Older than 1341 from tephra studies with lava flows to north-east<ref name=Hartley2016/>
|-
| align="center"| {{dts|1158}}
| {{unknown}}
| -
| align="center"| -
| {{unknown}}
| Older than 1158 from tephra studies with lava flows to north-east 
<ref name=Hartley2016/>
|- 
| align="center"| {{dts|1104}}
| {{unknown}}
| - 
| align="center"| -
| {{unknown}}
| Older than 1104 from tephra studies with lava flows to immediate north-east of caldera<ref name=Hartley2016/>
|- 
| align="center"| {{dts|871}}
| {{unknown}}
| - 
| align="center"| -
| {{unknown}}
| Older than 871 from tephra studies with lava flow to south-east of caldera<ref name=Hartley2016/> 
|- 
| align="center"| 1250 ± 300 BCE
| {{unknown}}
! style="background-color: #FF0;" | 0 
| align="center"| Major
| {{unknown}}
| Older than 1045 BC from tephra studies with large lava fields north and south of caldera<ref name=Hartley2016/> 
|-
| align="center"| 2050 ± 500 BCE
| {{unknown}}
! style="background-color: #FF0;" | 0 
| align="center"| Small
| {{unknown}}
| Older than 2285 BC from tephra studies<ref name=Hartley2016/>
|-
| align="center"| 3750 BCE
| {{unknown}}
| -
| align="center"| -
| {{unknown}}
| Basalt tephra A5700 from Torfdalsvatn<ref>{{cite journal|last1 =Harning|first1 =D.J.|last2 =Florian|first2 =C.R.|last3 =Geirsdóttir|first3 =Á.|last4 =Thordarson|first4 =T.|last5 =Miller|first5 = G.H.|last6 =Axford|first6 =Y.|last7 =Ólafsdóttir|first7 =S.|year =2024|title =High-resolution Holocene record from Torfdalsvatn, north Iceland, reveals natural and anthropogenic impacts on terrestrial and aquatic environments|journal =Climate of the Past Discussions|pages =1–41|doi =10.5194/cp-2024-26|doi-access =free}}</ref>
|-
| align="center"| 8874 ± 97 BCE 
| {{unknown}}
! style="background-color: #F80;" | 5 
| align="center"| Major
| {{unknown}}
| 1.5 ± 0.5 km3 DRE<ref name=Kearney2018/>
|}

=== Activity ===
In June 2010, Volcano expert Hazel Rymer said seismic activity was increasing at Askja.<ref>{{cite web|url=http://www.express.co.uk/posts/view/180291/Volcano-expert-warns-of-another-Icelandic-eruption|title=Volcano expert warns of another Icelandic eruption|author=Emma Pryer|work=Express.co.uk|accessdate=7 October 2014|date=2010-06-10}}</ref> The increased earthquake activity was located to the northeast of the [[central volcano]], in the direction of [[Herðubreið]]. It was ruled out that any activity from [[Eyjafjallajökull]] was responsible for the increase in activity at Askja. The news came as scientists continue to watch [[Katla volcano|Katla]]. In early April 2012 it was noted that the lake in the caldera was totally clear of ice, which usually does not happen until in June or July in a normal year. It was believed that increased geothermal activity in the volcano is heating the lake. Travel in the area was restricted until further research could be carried out.<ref>{{cite web|url=http://icelandreview.com/icelandreview/daily_news/Photos_Iceless_Iceland_Volcano_Lake_Causes_Speculation_0_388867.news.aspx|title=Photos: Iceless Iceland Volcano Lake Causes Speculation|work=Iceland Review|accessdate=7 October 2014|archive-date=2 July 2012|archive-url=https://web.archive.org/web/20120702104651/http://www.icelandreview.com/icelandreview/daily_news/Photos_Iceless_Iceland_Volcano_Lake_Causes_Speculation_0_388867.news.aspx|url-status=dead}}</ref>

In early September 2021, GPS and Satellite data showed that an inflation at the rate of five cm per month, most likely attributed to magma intrusion, of the caldera had started in August.<ref>{{Cite web|url=https://www.vedur.is/um-vi/frettir/land-ris-vid-oskju?|title=Land rís við Öskju &#124; Fréttir}}</ref> An Article published on September 9 from the Icelandic Meteorological Office(IMO) stated the Aviation Color Code was upgraded from "Green" to "Yellow" due to the changes.<ref>{{Cite web|title=Uncertainty level declared for the ongoing uplift at Askja volcano {{!}} News|url=https://en.vedur.is/about-imo/news/headline-for-askja-item|access-date=2021-09-09|website=Icelandic Meteorological office|language=en}}</ref> The Article also says, "Next week IMO and the Institute of Earth Sciences (UÍ) will potentiate the monitoring network around Askja to allow a better coverage and surveillance of the volcano." On 9 November 2022 deformation data showed continuing magma accumulation at depth, with accumulated uplift of {{cvt|40|cm}} since August 2021.<ref name=gvp/>