Zavaritski Caldera

The Zavaritski volcano contains three nested calderas, measuring {{convert|3|km|mi|sigfig=1|abbr=off}}, {{cvt|8|km|sigfig=1}} and {{cvt|10|km|sigfig=1}} in diameter. The youngest caldera, which is partially filled by Lake {{langr|ru-la|Biryuzovoe}}, was formed during the Holocene and features several young volcanic cones and lava domes. The lake surface sits at an elevation of {{convert|40|m|sigfig=1|abbr=off}} above sea level, with the lake bottom at {{val|30|u=m}} below sea level. Lake sediments overlying pumice deposits indicate that a previous caldera lake surface existed {{cvt|200|m|sigfig=1}} above sea level.

The last reported explosive eruption was recorded in November 1957. This destroyed a {{cvt|500|m|mi|frac=3|adj=on}} diameter cone{{cite book|last1=Gorshkov|first1=G S|title=Catalog of Active Volcanoes of the World and Solfatara Fields|date=1958|publisher=International Volcanological Association|location=Rome IAVCEI|pages=1–99|edition=7}} that reportedly grew pre-eruption and had formed a peninsula extending into the lake from the northeast caldera wall. The eruption filled the northwest section of the lake, including the emplacement of a {{cvt|350|m|mi|frac=4|adj=on}} wide, {{cvt|40|m|sigfig=1|adj=on}} high dome.

Research indicates that {{langr|ru-la|Zavaritski}} Caldera may have been the source of a high-magnitude explosive eruption that occurred in 1831, during the Northern Hemisphere summer.{{cite journal|last1=Hutchison|first1=William|last2=Sugden|first2=Patrick|last3=Burke|first3=Andrea|last4=Abbott|first4=Peter|last5=Ponomareva|first5=Vera V.|last6=Dirksen|first6=Oleg|last7=Portnyagin|first7=Maxim V.|last8=MacInnes|first8=Breanyn|last9=Bourgeois|first9=Joanne |last10=Fitzhugh |first10=Ben|last11=Verkerk|first11=Magali|last12=Aubry|first12=Thomas J.|last13=Engwell|first13=Samantha L.|last14=Svensson|first14=Anders|last15=Chellman|first15=Nathan J.|last16=McConnell|first16=Joseph R.|last17=Davies|first17=Siwan|last18=Sigl|first18=Michael|last19=Plunkett|first19=Gill|title=The 1831 CE mystery eruption identified as Zavaritskii caldera, Simushir Island (Kurils)|journal=Proceedings of the National Academy of Sciences|date=7 January 2025|volume=122|issue=1|pages=e2416699122|doi=10.1073/pnas.2416699122|display-authors=5|language=en|doi-access=free|pmid=39793052 |pmc=11725861 }}

Evidence for the eruption includes sulfate peaks in polar ice cores and from historical observations of atmospheric phenomena in Japanese records (such as observations of an abnormally colored sun). It is thought that the mass injection of sulfur from the eruption caused Northern Hemisphere climate cooling of {{convert|0.5|–|1.0|C-change|0}}, coincided with fluctuations in the Indian and African monsoons, and preceded major famines (including the Guntur famine of 1832 in India). However, the source of this major eruption has remained a mystery.

The researchers, led by volcanologist William Hutchison, conducted geochemical analyses of several Greenland ice cores. They found, coinciding with the sulphate peaks from the 1831 eruption, microscopic layers of tephra that chemically matched deposits from the most recent Plinian {{langr|ru-la|Zavaritski}} eruption, dated to the early 19th century. Modelling suggests that the eruption could have been a VEI 5/6-magnitude eruption event. The reconstructed radiative forcing of the eruption is comparable to the 1991 eruption of Mount Pinatubo, and may account for the climatic cooling observed between 1831–1833.

• List of volcanoes in Russia
• Tectonic–climatic interaction

{{reflist}}

• {{cite gvp|vn=290180|name=Zavaritzki Caldera}}
• Aerial image retrieve from [https://ntrs.nasa.gov/search.jsp NASA Technical Reports Server] on 19 April 2007.

{{Kuril Islands}}

Category:Simushir

Category:Active volcanoes

Category:Volcanic crater lakes

Category:Calderas of Russia

Category:Volcanoes of the Kuril Islands

Category:Pleistocene calderas

Category:Holocene calderas