Editing Askja (section)

=== 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/>