Editing Volcano (section)

{{Short description|Rupture in a planet's crust where material escapes}}
{{Redirect|Volcanic||Volcano (disambiguation)|and|Volcanic (disambiguation)}}
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{{Use Oxford spelling|date=November 2024}}
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[[File:Augustine volcano Jan 24 2006 - Cyrus Read.jpg|thumb|upright=1.35|[[Augustine Volcano]] (Alaska) during its eruptive phase on January 24, 2006]]
A '''volcano''' is commonly defined as a vent or fissure in the [[Crust (geology)|crust]] of a [[planetary-mass object]], such as [[Earth]], that allows hot [[lava]], [[volcanic ash]], and [[volcanic gas|gases]] to escape from a [[magma chamber]] below the surface.<ref name=gsa>{{cite book|title=What is a Volcano?|publisher=[[Geological Society of America]]|language=en|year=2010|isbn=978-0813724706|chapter= 1: What is a volcano?|editor-last1=Canon-Tapia|editor-first1=Edgardo|editor-last2=Szakács|editor-first2=Alexandru|page=3}}</ref>

On Earth, volcanoes are most often found where [[list of tectonic plates|tectonic plates]] are [[divergent boundary|diverging]] or [[convergent boundary|converging]], and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a [[mid-ocean ridge]], such as the [[Mid-Atlantic Ridge]], has volcanoes caused by divergent tectonic plates whereas the Pacific [[Ring of Fire]] has volcanoes caused by convergent tectonic plates. Volcanoes resulting from divergent tectonic activity are usually non-explosive whereas those resulting from convergent tectonic activity cause violent eruptions.<ref name=dkp>{{cite book|title=The Ultimate Visual Dictionary|year=2012|publisher=[[DK (publisher)|DK Pub.]]|language=en|pages=272–293|isbn=978-0-1434-1954-9|chapter=geology}}</ref><ref name="mor">"Mid-ocean ridge tectonics, volcanism and geomorphology." Geology 26, no. 455 (2001): 458. https://macdonald.faculty.geol.ucsb.edu/papers/Macdonald%20Mid-Ocean%20Ridge%20Tectonics.pdf</ref> Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the [[East African Rift]], the [[Wells Gray-Clearwater volcanic field]], and the [[Rio Grande rift]] in North America. Volcanism away from plate boundaries most likely arises from upwelling [[diapir]]s from the [[core–mantle boundary]] called [[mantle plume]]s, {{convert|3000|km|mi}} deep within Earth. This results in [[hotspot (geology)|hotspot volcanism]] or [[intraplate volcanism]], in which the plume may cause thinning of the crust and result in a [[volcanic island]] chain due to the continuous movement of the tectonic plate, of which the [[Hawaiian hotspot]] is an example.<ref name=bgs>{{cite web|title=How volcanoes form - British Geological Survey|website=[[British Geological Survey]]|access-date=25 December 2024|url=https://www.bgs.ac.uk/discovering-geology/earth-hazards/volcanoes/how-volcanoes-form-2/#:~:text=Volcanoes%20form%20here%20in%20two,produces%20an%20island%2Darc%20volcano}}</ref> Volcanoes are usually not created at [[transform fault|transform tectonic boundaries]] where two tectonic plates slide past one another.

Volcanoes, based on their frequency of eruption or volcanism, are referred to as either [[active volcano|active]] or extinct.<ref name="www.usgs.gov2">{{Cite web |last=Poland |first=Michael |date=2022-10-10 |title=Active, dormant, and extinct: Clarifying confusing classifications {{!}} U.S. Geological Survey |url=https://www.usgs.gov/observatories/yvo/news/active-dormant-and-extinct-clarifying-confusing-classifications |access-date=2023-11-14 |publisher=United States Geological Survey}}</ref> Active volcanoes have a history of volcanism and are likely to erupt again while extinct ones are not capable of eruption at all as they have no magma source. "Dormant" volcanoes have not erupted in a long time- generally accepted as since the start of the Holocene, about 12000 years ago- but may erupt again.<ref name="www.usgs.gov2" /> These categories aren't entirely uniform; they may overlap for certain examples.<ref name=dkp/><ref name=ade/><ref name=ng>{{cite web|title=Volcanoes|website=National Geographic Society|url=https://education.nationalgeographic.org/resource/volcanoes/|access-date=26 December 2024}}</ref>

Large eruptions can affect atmospheric temperature as ash and droplets of [[sulfuric acid]] obscure the Sun and cool Earth's [[troposphere]]. Historically, large volcanic eruptions have been followed by [[volcanic winter]]s which have caused catastrophic famines.<ref>{{cite journal|last1=Rampino|first1=M R|last2=Self|first2=S|last3=Stothers|first3=R B|title=Volcanic Winters|journal=Annual Review of Earth and Planetary Sciences|date=May 1988|volume=16|issue=1|pages=73–99|doi=10.1146/annurev.ea.16.050188.000445|bibcode=1988AREPS..16...73R|issn=0084-6597}}</ref>

Other planets besides Earth have volcanoes. For example, volcanoes are very numerous on Venus.<ref>{{Cite journal|last1=Hahn|first1=Rebecca M.|last2=Byrne|first2=Paul K.|date=April 2023|title=A Morphological and Spatial Analysis of Volcanoes on Venus|url=http://dx.doi.org/10.1029/2023je007753|journal=Journal of Geophysical Research: Planets|volume=128|issue=4|doi=10.1029/2023je007753|bibcode=2023JGRE..12807753H|s2cid=257745255|issn=2169-9097}}</ref> Mars has significant volcanoes.<ref>{{cite web|url=https://www.nasa.gov/solar-system/nasa-confirms-thousands-of-massive-ancient-volcanic-eruptions-on-mars/|title=NASA Confirms Thousands of Massive Ancient Volcanic Eruptions on Mars|access-date=12 November 2024|date=15 September 2021|first=William|last=Steigerwald|publisher=Goddard Space Flight Center, NASA|location=Greenbelt, Md, United States}}</ref> In 2009, a paper was published suggesting a new definition for the word 'volcano' that includes processes such as [[cryovolcanism]]. It suggested that a volcano be defined as 'an opening on a planet or moon's surface from which [[magma]], as defined for that body, and/or magmatic gas is erupted.'<ref>{{Cite journal|last1=Lopes|last2=Mitchell|last3=Williams|last4=Mitri|last5=Gregg|first1=R. M.|first2=K. L.|first3=D. A.|first4=G.|first5=T. K.|title=What is a Volcano? How planetary volcanism has changed our definition|url=https://ui.adsabs.harvard.edu/abs/2009AGUFM.V21H..08L/abstract|journal=AGU Fall Meeting Abstracts|date=2009|volume=2009|bibcode=2009AGUFM.V21H..08L}}</ref>

This article mainly covers volcanoes on Earth. See {{section link|nopage=y|Volcano|Volcanoes on other celestial bodies}} and [[cryovolcano]] for more information.