Editing Volcano (section)

==Volcanic features==
{{Further|Types of volcanoes}}
[[File:007_Volcano_eruption_of_Litli-Hrútur_in_Iceland_in_2023_Video_by_Giles_Laurent.webm|thumb|Video of lava agitating and bubbling in the volcanic eruption of Litli-Hrútur ([[Fagradalsfjall]]), Iceland, 2023]]
A volcano needs a reservoir of molten magma (e.g. a [[magma chamber]]), a conduit to allow magma to rise through the crust, and a vent to allow the magma to escape above the surface as lava. The erupted volcanic material (lava and tephra) that is deposited around the vent is known as a '''{{Visible anchor|volcanic edifice}}''', typically a volcanic cone or mountain.<ref name=dkp/><ref name="NPS-Anat">{{cite web|url=https://www.nps.gov/subjects/volcanoes/anatomy-of-a-volcano.htm|title=Anatomy of a Volcano|publisher=[[National Park Service]]|date=July 5, 2023|access-date=November 3, 2023}}</ref>

The most common perception of a volcano is of a [[conical]] mountain, spewing [[lava]] and poisonous [[volcanic gas|gases]] from a [[volcanic crater|crater]] at its summit; however, this describes just one of the many types of volcano. The features of volcanoes are varied. The structure and behaviour of volcanoes depend on several factors. Some volcanoes have rugged peaks formed by [[lava dome]]s rather than a summit crater while others have [[landscape]] features such as massive [[plateau]]s. Vents that issue volcanic material (including lava and [[volcanic ash|ash]]) and gases (mainly steam and magmatic gases) can develop anywhere on the [[landform]] and may give rise to smaller cones such as [[Puʻu ʻŌʻō|Pu{{okina}}u {{okina}}Ō{{okina}}ō]] on a flank of [[Kīlauea]] in Hawaii. [[Volcanic crater]]s are not always at the top of a mountain or hill and may be filled with lakes such as with [[Lake Taupō]] in New Zealand. Some volcanoes can be low-relief landform features, with the potential to be hard to recognize as such and be obscured by geological processes.<ref name=dkp/><ref name=usgs>{{cite web|title=The Pu'u'ō'ō Eruption Lasted 35 Years|date=22 November 2023|website=[[United States Geological Survey]]|url=https://www.usgs.gov/volcanoes/kilauea/science/puuoo-eruption-lasted-35-years|access-date=25 December 2024}}</ref><ref name=taupo>{{cite web|title=Lake Taupo - New Zealand, Map, Volcano, & Facts - Britannica|website=Britannica|access-date=25 December 2024|url=https://www.britannica.com/place/Lake-Taupo}}</ref>

Other types of volcano include [[mud volcano]]es, which are structures often not associated with known magmatic activity; and [[cryovolcano]]es (or ice volcanoes), particularly on some moons of [[Jupiter]], [[Saturn]], and [[Neptune]]. Active mud volcanoes tend to involve temperatures much lower than those of [[igneous]] volcanoes except when the mud volcano is actually a vent of an igneous volcano.

===Fissure vents===
{{Main|Fissure vent}}

[[File:Lakagigar Iceland 2004-07-01.jpg|right|thumbnail|[[Laki|Lakagigar]] fissure vent in [[Iceland]], the source of the [[Laki#Consequences in Iceland|major world climate alteration of 1783–84]], has a chain of volcanic cones along its length.]]
[[Fissure vent|Volcanic fissure vents]] are generally found at [[Divergent boundary|diverging plate boundaries]], they are flat, linear fractures through which [[basaltic lava]] emerges. These kinds of volcanoes are non-explosive and the basaltic lava tends to have a low viscosity and solidifies slowly leading to a gentle sloping basaltic [[Volcanic plateau|lava plateau]]. They often relate or constitute shield volcanoes<ref name=dkp/><ref name=nps/>

===Shield volcanoes===
{{Main|Shield volcano}}

[[File:Skjaldbreidur Herbst 2004.jpg|left|thumbnail|[[Skjaldbreiður]], a shield volcano whose name means "broad shield"]]
Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity basaltic or andesitic lava that can flow a great distance from a vent. They generally do not explode catastrophically but are characterized by relatively gentle [[effusive eruption]]s.<ref name=dkp/> Since low-viscosity magma is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in [[Iceland]], as well.<ref name=nps>{{cite web|title=Shield Volcanoes (U.S. National Park Service)|website=[[National Park Service]]|access-date=25 December 2024|url=https://www.nps.gov/articles/000/shield-volcanoes.htm#:~:text=Hawai'i%20Volcanoes%20National%20Park,active%20volcano%20on%20the%20planet.}}</ref> [[Olympus Mons]], an extinct martian shield volcano is the largest known volcano in the [[Solar System]].<ref name=msv>{{cite web|title=Olympus Mons - Description, Height, & Facts - Britannica|website=Britannica|url=https://www.britannica.com/place/Olympus-Mons|access-date=25 December 2024}}</ref>

===Lava domes===
[[File:East Dome Mount St. Helens.jpg|thumb|East dome, a lava dome located on the lower east flank of St. Helens, part of the Sugar Bowl Eruptive Period (1800 YA).]]
{{Main|Lava dome}}
[[Lava dome]]s, also called dome volcanoes, have steep convex sides built by slow eruptions of highly viscous lava, for example, [[rhyolite]].<ref name=dkp/> They are sometimes formed within the crater of a previous volcanic eruption, as in the case of [[Mount St. Helens]], but can also form independently, as in the case of [[Lassen Peak]]. Like stratovolcanoes, they can produce violent, explosive eruptions, but the lava generally does not flow far from the originating vent.

===Cryptodomes===
Cryptodomes are formed when viscous lava is forced upward causing the surface to bulge. The [[1980 eruption of Mount St. Helens]] was an example; lava beneath the surface of the mountain created an upward bulge, which later collapsed down the north side of the mountain.

===Cinder cones===
{{Main|volcanic cone|Cinder cone}}
[[File:Izalco Volcano.jpg|thumb|[[Izalco (volcano)|Izalco volcano]], the youngest volcano in El Salvador. Izalco erupted almost continuously from 1770 (when it formed) to 1958, earning it the nickname of "Lighthouse of the Pacific".]]

Cinder cones result from eruptions of mostly small pieces of [[scoria]] and [[Pyroclastic rock|pyroclastics]] (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps {{convert|30 to 400|m|ft|-2}} high. Most cinder cones erupt only once and some may be found in [[monogenetic volcanic field]]s that may include other features that form when magma comes into contact with water such as [[maar]] explosion craters and [[tuff ring]]s.<ref name="Thomas2000">David S.G. Thomas and Andrew Goudie (eds.), ''The Dictionary of Physical Geography'' (Oxford: Blackwell, 2000), 301. {{ISBN|0-631-20473-3}}.</ref> Cinder cones may form as [[parasitic cone|flank vents]] on larger volcanoes, or occur on their own. [[Parícutin]] in Mexico and [[Sunset Crater]] in [[Arizona]] are examples of cinder cones. In [[New Mexico]], [[Caja del Rio]] is a [[volcanic field]] of over 60 cinder cones.

Based on satellite images, it has been suggested that cinder cones might occur on other terrestrial bodies in the Solar system too; on the surface of Mars and the Moon.<ref>{{cite journal|last1=Wood|first1=C.A.|title=Cindercones on Earth, Moon and Mars|journal=Lunar and Planetary Science|volume=X|year=1979|pages=1370–1372|bibcode=1979LPI....10.1370W}}</ref><ref>{{Cite journal|last1=Meresse|first1=S.|last2=Costard|first2=F.O.|last3=Mangold|first3=N.|last4=Masson|first4=P.|last5=Neukum|first5=G.|title=Formation and evolution of the chaotic terrains by subsidence and magmatism: Hydraotes Chaos, Mars|doi=10.1016/j.icarus.2007.10.023|journal=Icarus|volume=194|issue=2|pages=487|year=2008|bibcode=2008Icar..194..487M}}</ref><ref name="Ulysses">{{Cite journal|doi=10.1016/j.icarus.2011.11.030|title=A unique volcanic field in Tharsis, Mars: Pyroclastic cones as evidence for explosive eruptions|year=2012|last1=Brož|first1=P.|last2=Hauber|first2=E.|journal=Icarus|volume=218|issue=1|pages=88|bibcode=2012Icar..218...88B}}</ref><ref name="mesic">{{Cite journal|last1=Lawrence|first1=S.J.|last2=Stopar|first2=J.D.|last3=Hawke|first3=B.R.|last4=Greenhagen|first4=B.T.|last5=Cahill|first5=J.T.S.|last6=Bandfield|first6=J.L.|last7=Jolliff|first7=B.L.|last8=Denevi|first8=B.W.|last9=Robinson|first9=M.S. | last10 = Glotch | first10 = T.D.|last11=Bussey|first11=D.B.J.|last12=Spudis|first12=P.D.|last13=Giguere|first13=T.A.|last14=Garry|first14=W.B.|title=LRO observations of morphology and surface roughness of volcanic cones and lobate lava flows in the Marius Hills|doi=10.1002/jgre.20060|journal=Journal of Geophysical Research: Planets|volume=118|issue=4|pages=615|year=2013|bibcode=2013JGRE..118..615L|doi-access=free}}</ref>

===Stratovolcanoes (composite volcanoes)===
[[File:Volcano scheme.svg|thumb|upright=1.4|'''Cross-section through a [[stratovolcano]] (vertical scale is exaggerated)''': {{Div col|colwidth=30em}}{{ordered list
    |1=Large magma chamber
    |2=Bedrock
    |3=Conduit (pipe)
    |4=Base
    |5=Sill
    |6=Dike
    |7=Layers of ash emitted by the volcano
    |8=Flank
    |9=Layers of lava emitted by the volcano
    |10=Throat
    |11=Parasitic cone
    |12=Lava flow
    |13=Vent
    |14=Crater
    |15=Ash cloud
}}{{div col end}}]]
{{Main|Stratovolcano}}
Stratovolcanoes are tall conical mountains composed of lava flows and [[tephra]] in alternate layers, the [[strata]] that gives rise to the name. They are also known as ''composite volcanoes'' because they are created from multiple structures during different kinds of eruptions; the main conduit bringing magma to the surface branches into multiple secondary conduits and occasional [[laccolith]]s or [[Sill (geology)|sill]]s, the branching conduits may form [[parasitic cone]]s on the flanks of the main cone.<ref name=dkp/> Classic examples include [[Mount Fuji]] in Japan, [[Mayon Volcano]] in the Philippines, and [[Mount Vesuvius]] and [[Stromboli]] in Italy.
[[File:Mount Vesuvius Araucaria.jpg|thumb|left|Mt. Vesuvius, a stratovolcano, [[Gulf of Naples]].]]

[[volcanic ash|Ash]] produced by the [[explosive eruption]] of stratovolcanoes has [[recorded history|historically]] posed the greatest volcanic hazard to civilizations. The lavas of stratovolcanoes are higher in silica, and therefore much more viscous, than lavas from shield volcanoes. High-silica lavas also tend to contain more dissolved gas. The combination is deadly, promoting [[explosive eruption]]s that produce great quantities of ash, as well as [[pyroclastic surge]]s like the one that destroyed the city of Saint-Pierre in Martinique in 1902. They are also steeper than shield volcanoes, with slopes of 30–35° compared to slopes of generally 5–10°, and their loose [[tephra]] are material for dangerous [[lahar]]s.<ref>{{Cite book|url=https://books.google.com/books?id=eJopFDVRgYMC&pg=PA115|title=Volcanoes: Global Perspectives|first1=John P.|last1=Lockwood|first2=Richard W.|last2=Hazlett|year=2010|isbn=978-1-4051-6250-0|page=552|publisher=Wiley}}</ref> Large pieces of tephra are called [[volcanic bomb]]s. Big bombs can measure more than {{convert|4|ft|m|order=flip}} across and weigh several tons.<ref>Berger, Melvin, Gilda Berger, and Higgins Bond. "Volcanoes-why and how ." Why do volcanoes blow their tops?: Questions and answers about volcanoes and earthquakes. New York: Scholastic, 1999. 7. Print.</ref>

===Supervolcanoes===
[[File:Lake Taupo (31071970884).jpg|thumb|Lake Taupō, a volcanogenic lake in the caldera of [[Taupō Volcano|Taupō supervolcano]], New Zealand.]]
{{Main|Supervolcano}}
{{see also|List of largest volcanic eruptions}}
A supervolcano is defined as a volcano that has experienced one or more eruptions that produced over {{convert|1000|km3|cumi}} of volcanic deposits in a single explosive event.<ref>{{cite web|url=https://volcanoes.usgs.gov/volcanoes/yellowstone/yellowstone_sub_page_49.html|title=Questions About Supervolcanoes|publisher=United States Geological Survey|department=Yellowstone Volcano Observatory|date=August 21, 2015|access-date=August 22, 2017|url-status=live|archive-url=https://web.archive.org/web/20170703184836/https://volcanoes.usgs.gov/volcanoes/yellowstone/yellowstone_sub_page_49.html|archive-date=July 3, 2017}}</ref> Such eruptions occur when a very large magma chamber full of gas-rich, silicic magma is emptied in a catastrophic [[caldera]]-forming eruption. Ash flow [[tuff]]s emplaced by such eruptions are the only volcanic product with volumes rivalling those of [[flood basalt]]s.{{sfn|Philpotts|Ague|2009|p=77}}

Supervolcano eruptions, while the most dangerous type, are very rare; [[Supervolcano#Known super eruptions|four are known from the last million years]], and about 60 historical VEI 8 eruptions have been identified in the geologic record over millions of years. A supervolcano can produce devastation on a continental scale, and severely cool global temperatures for many years after the eruption due to the huge volumes of [[sulfur]] and ash released into the atmosphere.

Because of the enormous area they cover, and subsequent concealment under vegetation and glacial deposits, supervolcanoes can be difficult to identify in the geologic record without careful [[geological map]]ping.<ref>{{cite journal|jstor=24968920|title=Giant Volcanic Calderas|last1=Francis|first1=Peter|journal=Scientific American|year=1983|volume=248|issue=6|pages=60–73|doi=10.1038/scientificamerican0683-60|bibcode=1983SciAm.248f..60F}}</ref> Known examples include [[Yellowstone Caldera]] in [[Yellowstone National Park]] and [[Valles Caldera]] in [[New Mexico]] (both western United States); [[Lake Taupō]] in New Zealand; [[Lake Toba]] in [[Sumatra]], Indonesia; and [[Ngorongoro Crater]] in Tanzania.

====Caldera volcanoes====
[[File:Crater Lake winter pano2.jpg|thumb|Crater lake, a volcanic lake in [[Oregon]].]]
Volcanoes that, though large, are not large enough to be called supervolcanoes, may also form calderas (collapsed crater) in the same way. There may be active or dormant cones inside of the caldera or even a lake, such lakes are called [[Volcanogenic lake]]s, or simply, volcanic lakes.<ref>{{cite journal|last1=Druitt|first1=T. H.|last2=Costa|first2=F.|last3=Deloule|first3=E.|last4=Dungan|first4=M.|last5=Scaillet|first5=B.|title=Decadal to monthly timescales of magma transfer and reservoir growth at a caldera volcano|journal=Nature|volume=482|issue=7383|date=2012|issn=0028-0836|doi=10.1038/nature10706|pages=77–80|pmid=22297973|bibcode=2012Natur.482...77D|hdl=10220/7536|hdl-access=free}}</ref><ref name=dkp/>

===Submarine volcanoes===
{{Main|Submarine volcano}}
{{See also|Subaqueous volcano}}
[[File:Tonga Volcano Eruption 2022-01-15 0320Z to 0610Z Himawari-8 visible.gif|left|thumb|Satellite images of the January 15, 2022, eruption of [[Hunga Tonga-Hunga Haʻapai]]]]
Submarine volcanoes are common features of the ocean floor. Volcanic activity during the [[Holocene]] Epoch has been documented at only 119 submarine volcanoes, but there may be more than one million geologically young submarine volcanoes on the ocean floor.<ref name="GVPDatabase2020">{{cite web|url=https://volcano.si.edu/list_volcano_holocene.cfm|title=Holocene Volcano List|publisher=[[Global Volcanism Program]] Volcanoes of the World (version 4.9.1)|editor-last=Venzke|editor-first=E.|year=2013|access-date=November 18, 2020}}</ref><ref name="GVP-FAQ">{{cite web|url=https://volcano.si.edu/faq/index.cfm?question=activevolcanoes|title=How many active volcanoes are there?|publisher=[[Global Volcanism Program]] Volcanoes of the World (version 4.9.1)|editor-last=Venzke|editor-first=E.|year=2013|access-date=November 18, 2020}}</ref> In shallow water, active volcanoes disclose their presence by blasting steam and rocky debris high above the ocean's surface. In the deep ocean basins, the tremendous weight of the water prevents the explosive release of steam and gases; however, submarine eruptions can be detected by [[hydrophone]]s and by the discoloration of water because of [[volcanic gas]]es. [[Pillow lava]] is a common eruptive product of submarine volcanoes and is characterized by thick sequences of discontinuous pillow-shaped masses which form underwater. Even large submarine eruptions may not disturb the ocean surface, due to the rapid cooling effect and increased buoyancy in water (as compared to air), which often causes volcanic vents to form steep pillars on the ocean floor. [[Hydrothermal vent]]s are common near these volcanoes, and [[Black smoker|some support peculiar ecosystems]] based on [[chemotroph]]s feeding on dissolved minerals. Over time, the formations created by submarine volcanoes may become so large that they break the ocean surface as new islands or floating [[pumice raft]]s.

In May and June 2018, a multitude of [[seismic]] signals were detected by [[earthquake]] monitoring agencies all over the world. They took the form of unusual humming sounds, and some of the signals detected in November of that year had a duration of up to 20 minutes. An [[oceanographic]] research campaign in May 2019 showed that the previously mysterious humming noises were caused by the formation of a submarine volcano off the coast of [[Mayotte]].<ref>{{cite web|language=en|title=Origin of mystery humming noises heard around the world, uncovered|author=Ashley Strickland|publisher=CNN|date=January 10, 2020|url=https://www.msn.com/en-us/news/technology/origin-of-mystery-humming-noises-heard-around-the-world-uncovered/ar-BBYN2oY?ocid=spartanntp}}</ref>

===Subglacial volcanoes===
{{Main|Subglacial volcano}}
Subglacial volcanoes develop underneath [[ice cap]]s. They are made up of lava plateaus capping extensive pillow lavas and [[palagonite]]. These volcanoes are also called table mountains, [[tuya]]s,{{sfn|Philpotts|Ague|2009|p=66}} or (in Iceland) mobergs.<ref>{{cite book|editor1-last=Allaby|editor1-first=Michael|title=A dictionary of geology and earth sciences|location=Oxford|publisher=Oxford University Press|isbn=9780199653065|edition=Fourth|chapter=Tuya|date=July 4, 2013}}</ref> Very good examples of this type of volcano can be seen in Iceland and in [[British Columbia]]. The origin of the term comes from [[Tuya Butte]], which is one of the several tuyas in the area of the [[Tuya River]] and [[Tuya Range]] in northern British Columbia. Tuya Butte was the first such [[landform]] analysed and so its name has entered the geological literature for this kind of volcanic formation.<ref>{{cite journal|doi=10.2475/ajs.245.9.560|last=Mathews|first=W. H.|title=Tuyas, flat-topped volcanoes in northern British Columbia|journal=[[American Journal of Science]]|volume=245|issue=9|pages=560–570|date=September 1, 1947|url=http://www.ajsonline.org/cgi/content/abstract/245/9/560|bibcode=1947AmJS..245..560M|access-date=November 27, 2020|archive-date=September 29, 2011|archive-url=https://web.archive.org/web/20110929220601/http://www.ajsonline.org/cgi/content/abstract/245/9/560|url-status=dead|url-access=subscription}}</ref> The [[Tuya Mountains Provincial Park]] was recently established to protect this unusual landscape, which lies north of [[Tuya Lake]] and south of the [[Jennings River]] near the boundary with the [[Yukon Territory]].

===Hydrothermal features===
Hydrothermal features, for example [[geyser]]s, [[fumarole]]s, [[Mudpot|mud pools]], [[mud volcano]]es, [[hot spring]]s and acidic hot springs involve water as well as geothermal or magmatic activity. Such features are common around volcanoes and are often indicative of volcanism.<ref name=dkp/><ref name=sd>{{cite book|title=Treatise on Geomorphology|edition=2nd|year=2022|publisher=[[Elsevier Inc.]]|isbn=978-0-12-818235-2}}</ref>

====Mud volcanoes====
[[File:Gobustan mud volcano.jpg|thumb|Mud volcano at [[Gobustan State Historical and Cultural Reserve|Gobustan]]]]
{{Main|Mud volcano}}
[[Mud volcano]]es or mud domes are conical structures created by eruption of liquids and gases, particularly mud (slurries), water and gases, although several activities may contribute. The largest mud volcanoes are {{convert|10|km|mi}} in diameter and reach {{convert|700|m|ft}} high.<ref>{{cite journal|last1=Mazzini|first1=Adriano|last2=Etiope|first2=Giuseppe|title=Mud volcanism: An updated review|journal=Earth-Science Reviews|date=May 2017|volume=168|pages=81–112|doi=10.1016/j.earscirev.2017.03.001|bibcode=2017ESRv..168...81M|hdl=10852/61234|hdl-access=free}}</ref><ref>{{cite journal|last1=Kioka|first1=Arata|last2=Ashi|first2=Juichiro|title=Episodic massive mud eruptions from submarine mud volcanoes examined through topographical signatures|journal=Geophysical Research Letters|date=October 28, 2015|volume=42|issue=20|pages=8406–8414|doi=10.1002/2015GL065713|bibcode=2015GeoRL..42.8406K|doi-access=free}}</ref> Mud volcanoes can be seen off the shore of [[Indonesia]], on the island of [[Baratang Island|Baratang]], in [[Balochistan, Pakistan|Balochistan]] and in central Asia.

====Fumarole====
{{main|Fumarole}}

[[Fumarole]]s are vents on the surface from which hot steam and volcanic gases erupt due to the presence of superheated groundwater, these may indicate volcanic activity. Fumaroles erupting sulfurous gases are also often called solfataras.<ref name=old>{{cite web|title=fumarole noun - Definition, pictures, pronunciation and usage notes - Oxford Advanced Learner's Dictionary at OxfordLearnersDictionaries.com|url=https://www.oxfordlearnersdictionaries.com/definition/english/fumarole|website=Oxford Learner's Dictionary|access-date=25 December 2024}}</ref><ref name=dkp/>

====Geysers====
{{main|Geyser}}

[[File:Yellowstone Castle Geysir Edit.jpg|thumb|Castle geyser eruption, [[Yellowstone National Park]].]]
Geysers are springs which will occasionally erupt and discharge hot water and steam. Geysers may indicate ongoing magmatism, water underground is heated by hot rocks and [[steam]] [[Vapor pressure|pressure]] builds up before being released along with a jet of hot water. Almost half of all active geysers are present in Yellowstone National Park, US.<ref name=dkp/><ref name=nps2>{{cite web|title=Yellowstone National Park (U.S. National Park Service)|website=[[National Park Service]]|url=https://www.nps.gov/yell/index.htm|access-date=26 December 2024}}</ref>