Editing Volcano (section)

===Hazards===
{{Main|Volcanic hazard}}
There are many different [[types of volcanic eruptions]] and associated activity: [[phreatic eruptions]] (steam-generated eruptions), explosive eruptions of high-[[silica]] lava (e.g., [[rhyolite]]), effusive eruptions of low-silica lava (e.g., [[basalt]]), [[sector collapse]]s, [[pyroclastic flow]]s, [[lahar]]s (debris flows) and [[Volcanic gas|volcanic gas emissions]]. These can pose a hazard to humans. Earthquakes, [[hot spring]]s, [[fumarole]]s, [[mud pot]]s and [[geyser]]s often accompany volcanic activity.

Volcanic gases can reach the stratosphere, where they form [[sulfuric acid]] aerosols that can reflect solar radiation and lower surface temperatures significantly.<ref>{{cite journal|last1=Miles|first1=M.G.|last2=Grainger|first2=R.G.|last3=Highwood|first3=E.J.|title=The significance of volcanic eruption strength and frequency for climate|journal=Quarterly Journal of the Royal Meteorological Society|year=2004|volume=130|issue=602|pages=2361–2376|doi=10.1256/qj.03.60|url=http://eodg.atm.ox.ac.uk/eodg/papers/2004Miles1.pdf|bibcode=2004QJRMS.130.2361M|s2cid=53005926}}

</ref> Sulfur dioxide from the eruption of [[Huaynaputina]] may have caused the [[Russian famine of 1601–1603]].<ref>{{cite web|author=University of California – Davis|title=Volcanic Eruption Of 1600 Caused Global Disruption|date=April 25, 2008|work=ScienceDaily|url=https://www.sciencedaily.com/releases/2008/04/080423135236.htm}}</ref> Chemical reactions of sulfate aerosols in the stratosphere can also damage the [[ozone layer]], and acids such as [[hydrogen chloride]] (HCl) and hydrogen fluoride (HF) can fall to the ground as [[acid rain]]. Excessive fluoride salts from eruptions have poisoned [[livestock]] in Iceland on multiple occasions.<ref>{{cite book|last=Thorarinsson|first=Sigurdur|author-link=Sigurdur Thorarinsson|others=trans. Jóhann Hannesson, Pétur Karlsson|title=Hekla, A Notorious Volcano|year=1970|publisher=Almenna bókafélagið|location=Reykjavík}}</ref>{{rp|pp=39–58}} [[Explosive eruption|Explosive volcanic eruptions]] release the greenhouse gas [[carbon dioxide]] and thus provide a deep source of [[carbon]] for [[biogeochemical cycle]]s.<ref>{{citation-attribution|1={{cite web|url=http://pubs.usgs.gov/of/1997/of97-262/of97-262.html|title=Impacts of Volcanic Gases on Climate, the Environment, and People|first1=Kenneth A.|last1=McGee|first2=Michael P.|last2=Doukas|first3=Richard|last3=Kessler|first4=Terrence M.|last4=Gerlach|date=May 1997|publisher=United States Geological Survey|access-date=August 9, 2014}} }}</ref>

Ash thrown into the air by eruptions can present a hazard to aircraft, especially [[jet aircraft]] where the particles can be melted by the high operating temperature; the melted particles then adhere to the [[turbine]] blades and alter their shape, disrupting the operation of the turbine. This can cause major disruptions to air travel.

[[File:Large eruptions.jpg|thumb|upright=1.3|Comparison of major United States prehistoric eruptions ([[VEI|VEI 7 and 8]]) with major historical volcanic eruptions in the 19th and 20th century (VEI 5, 6 and 7). From left to right: Yellowstone 2.1 Ma, Yellowstone 1.3 Ma, Long Valley 6.26 Ma, Yellowstone 0.64 Ma . 19th century eruptions: Tambora 1815, Krakatoa 1883. 20th century eruptions: Novarupta 1912, St. Helens 1980, Pinatubo 1991.]]

A [[volcanic winter]] is thought to have taken place around 70,000 years ago after the [[supereruption]] of [[Lake Toba]] on Sumatra island in Indonesia.<ref>{{cite web|title=Supervolcano eruption – in Sumatra – deforested India 73,000 years ago|url=https://www.sciencedaily.com/releases/2009/11/091123142739.htm|website=ScienceDaily|date=November 24, 2009}}</ref> This may have created a [[Toba catastrophe theory|population bottleneck]] that affected the genetic inheritance of all humans today.<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/science/nature/2975862.stm|title=When humans faced extinction|publisher=BBC|date=June 9, 2003|access-date=January 5, 2007}}</ref> Volcanic eruptions may have contributed to major extinction events, such as the [[Ordovician-Silurian extinction events|End-Ordovician]], [[Permian-Triassic]], and [[Late Devonian extinction|Late Devonian]] [[mass extinction]]s.<ref>{{cite web|last1=O'Hanlon|first1=Larry|title=Yellowstone's Super Sister|url=http://www.discovery.com/convergence/supervolcano/others/others_07.html|website=Discovery Channel|archive-url=https://web.archive.org/web/20050314025022/http://dsc.discovery.com/convergence/supervolcano/others/others_07.html|archive-date=March 14, 2005|date=March 14, 2005}}</ref>

The 1815 eruption of [[Mount Tambora]] created global climate anomalies that became known as the "[[Year Without a Summer]]" because of the effect on North American and European weather.<ref>''[https://books.google.com/books?id=ipNcKc0Mv5IC&pg=PA155 Volcanoes in human history: the far-reaching effects of major eruptions]''. Jelle Zeilinga de Boer, Donald Theodore Sanders (2002). [[Princeton University Press]]. p. 155. {{ISBN|0-691-05081-3}}</ref> The freezing winter of 1740–41, which led to widespread [[Irish Famine (1740–1741)|famine]] in northern Europe, may also owe its origins to a volcanic eruption.<ref>{{cite web|last1=Ó Gráda|first1=Cormac|title=Famine: A Short History|url=http://press.princeton.edu/chapters/s8857.html|publisher=Princeton University Press|archive-url=https://web.archive.org/web/20160112061115/http://press.princeton.edu/chapters/s8857.html|archive-date=January 12, 2016|date=February 6, 2009}}</ref>