Editing Volcano (section)

==Volcanic eruptions==
{{Main|Volcanic eruption}}

{{As of|2022|12}}, the [[Smithsonian Institution]]'s [[Global Volcanism Program]] database of volcanic eruptions in the [[Holocene]] [[Epoch (geology)|Epoch]] (the last 11,700 years) lists 9,901 confirmed eruptions from 859 volcanoes. The database also lists 1,113 uncertain eruptions and 168 discredited eruptions for the same time interval.<ref name="GVP501">{{cite journal|url=https://volcano.si.edu/search_eruption.cfm|title=Database Search|journal=Volcanoes of the World (Version 5.0.1)|publisher=[[Smithsonian Institution]] [[Global Volcanism Program]]|date=December 19, 2022|access-date=January 12, 2023|author=Venzke, E. (compiler)|editor-first1=Edward|editor-last1=Venzke|doi=10.5479/si.GVP.VOTW5-2022.5.0|url-access=subscription}}</ref><ref name="Volc_Count">{{cite journal|url=https://volcano.si.edu/faq/index.cfm?question=activevolcanoes|title=How many active volcanoes are there?|journal=Volcanoes of the World (Version 5.0.1)|publisher=[[Smithsonian Institution]] [[Global Volcanism Program]]|date=December 19, 2022|access-date=January 12, 2023|author=Venzke, E. (compiler)|editor-first1=Edward|editor-last1=Venzke|doi=10.5479/si.GVP.VOTW5-2022.5.0|url-access=subscription}}</ref>

[[File:Volcanic injection.svg|thumb|Schematic of volcano injection of aerosols and gases]]
Eruption styles are broadly divided into magmatic, phreatomagmatic (hydrovolcanic), and phreatic eruptions.<ref name="vol cash">{{cite book|title=Volcanic Ash|publisher=[[University of California Press]]|page=246|last1=Heiken|first1=G.|last2=Wohletz|first2=K.|name-list-style=amp <!--|access-date=3 August 2010 -->}}</ref> The intensity of explosive volcanism is expressed using the [[volcanic explosivity index]] (VEI), which ranges from 0 for Hawaiian-type eruptions to 8 for supervolcanic eruptions:<ref>{{cite journal|last1=Newhall|first1=Christopher G.|last2=Self|first2=Stephen|year=1982|title=The Volcanic Explosivity Index (VEI): An Estimate of Explosive Magnitude for Historical Volcanism|url=http://www.agu.org/books/hg/v002/HG002p0143/HG002p0143.pdf|journal=[[Journal of Geophysical Research]]|volume=87|issue=C2|pages=1231–1238|bibcode=1982JGR....87.1231N|doi=10.1029/JC087iC02p01231|archive-url=https://web.archive.org/web/20131213194307/http://www.agu.org/books/hg/v002/HG002p0143/HG002p0143.pdf|archive-date=December 13, 2013}}</ref><ref name=nps3>{{cite web|title=Eruption Classifications - Volcanoes, Craters & Lava Flows (U.S. National Park Service)|website=[[National Park Service]]|url=https://www.nps.gov/subjects/volcanoes/eruption-classifications.htm|access-date=26 December 2024}}</ref>

* Magmatic eruptions are driven primarily by gas release due to decompression.<ref name="vol cash"/> Low-viscosity magma with little dissolved gas produces relatively gentle effusive eruptions. High-viscosity magma with a high content of dissolved gas produces violent [[explosive eruption]]s. The range of observed eruption styles is expressed from historical examples.
* [[Hawaiian eruption]]s are typical of volcanoes that erupt mafic lava with a relatively low gas content. These are almost entirely effusive, producing local [[lava fountain]]s and highly fluid lava flows but relatively little tephra. They are named after the [[Hawaii hotspot|Hawaiian volcanoes]]. The eruption column from these eruptions does not exceed {{convert|2|km|mi}} in height.
* [[Strombolian eruption]]s are characterized by moderate viscosities and dissolved gas levels. They are characterized by frequent but short-lived eruptions that can produce eruptive columns hundreds of meters high, which can also be seen in a  [[gas slug]]. Their primary product is [[scoria]]. They are named after [[Stromboli]].
* [[Vulcanian eruption]]s are characterized by yet higher viscosities and partial crystallization of magma, which is often intermediate in composition. Eruptions take the form of short-lived explosions for several hours, which destroy a central dome and eject large lava blocks and bombs. This is followed by an effusive phase that rebuilds the central dome. Vulcanian eruptions are named after [[Vulcano]]. Eruption columns from these eruptions do not exceed {{convert|20|km|mi}} in height.
* [[Peléan eruption]]s are more violent still, being characterized by dome growth and collapse that produces various kinds of pyroclastic flows. They are named after [[Mount Pelée]].
* [[Plinian eruption]]s are characterized by sustained huge eruption columns whose collapse produces catastrophic pyroclastic flows. They are named after [[Pliny the Younger]], who chronicled the Plinian [[eruption of Mount Vesuvius in 79]] AD.
* Ultra-Plinian eruptions are the largest of all volcanic eruptions are more intense, have a higher eruption rate than Plinian ones, form higher eruption columns and may form large calderas. These eruptions produce rhyolitic lava, tephra, [[pumice]] and thick pyroclastic flows that cover vast areas and may produce widespread [[Volcanic ash|ash-fall]] deposits. Examples are [[Mount Mazama|Mt. Mazama]] and Yellowstone.
* [[Phreatomagmatic eruption]]s (hydrovolcanic) are characterized by interaction of rising magma with [[groundwater]]. They are driven by the resulting rapid buildup of pressure in the [[Superheating|superheated]] groundwater.
* [[Phreatic eruption]]s are characterized by superheating of groundwater that comes in contact with hot rock or magma. They are distinguished from phreatomagmatic eruptions because the erupted material is all [[Country rock (geology)|country rock]]; no magma is erupted.