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The Volcanoes Portal

Mount St. Helens

A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface. Violent explosive eruptions from such vents often produce craters or calderas and coat extensive areas in volcanic ash, while the lava from comparatively gentle effusive eruptions may eventually form large plains, cones or mountains.

Volcanoes are generally found where tectonic plates are pulled apart or come together. A mid-oceanic ridge, such as the Mid-Atlantic Ridge, hosts volcanoes caused by divergent tectonic plates pulling apart; the Pacific Ring of Fire contains many volcanoes caused by convergent tectonic plates coming together. By contrast, volcanoes are not commonly created at transform boundaries, where two tectonic plates slide past one another.

Volcanoes can be caused by mantle plumes, the resulting hotspots, for example at Hawaii, can occur far from plate boundaries. Hotspot volcanoes are also found elsewhere in the solar system, especially on rocky planets and moons. Intraplate volcanoes can also form where there is stretching and thinning of the Earth's crust, as in the Wells Gray-Clearwater volcanic field and the Rio Grande Rift in North America and the European Rhine Graben with its Eifel volcanoes.

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The moon Enceladus
Enceladus is the sixth-largest moon of Saturn. It was discovered in 1789 by William Herschel, until the two Voyager spacecraft passed near it in the early 1980s, very little was known about this small moon besides the identification of water ice on its surface. The Voyagers showed that Enceladus is only 500 km in diameter and reflects almost 100% of the sunlight that strikes it. Voyager 1 found that Enceladus orbited in the densest part of Saturn's diffuse E ring, indicating a possible association between the two, while Voyager 2 revealed that despite the moon's small size, it had a wide range of terrains ranging from old, heavily cratered surfaces to young, tectonically deformed terrain, with some regions with surface ages as young as 100 million years old. The Cassini spacecraft of the mid- to late 2000s acquired additional data on Enceladus, answering a number of the mysteries opened by the Voyager spacecraft and starting a few new ones. Cassini performed several close flybys of Enceladus in 2005, revealing the moon's surface and environment in greater detail. In particular, the probe discovered a water-rich plume venting from the moon's south polar region, this discovery, along with the presence of escaping internal heat and very few (if any) impact craters in the south polar region, shows that Enceladus is geologically active today. Moons in the extensive satellite systems of gas giants often become trapped in orbital resonances that lead to forced libration or orbital eccentricity; proximity to the planet can then lead to tidal heating of the satellite's interior, offering a possible explanation for the activity.

Selected biography

Wolfgang Waltershausen
Wolfgang Sartorius Freiherr von Waltershausen (December 17, 1809 – March 16, 1876) was a German geologist. Waltershausen was born at Göttingen and educated at the University of Göttingen. There he devoted his attention to physical and natural science, and in particular to mineralogy. Waltershausen's father, Georg, was a writer, lecturer and professor of economics and history at Göttingen, best known for his role of translator and popularizer of Adam Smith's Wealth of Nations.

During a tour in 1834-1835 Waltershausen carried out a series of magnetic observations in various parts of Europe, he then gave his attention to an exhaustive investigation of the volcano of Mount Etna, in Sicily, and carried on the work with some interruptions until 1843. The chief result of this undertaking was his great Atlas des Ätna (1858–1861), in which he distinguished the lava streams formed during the later centuries.

After his return from Mount Etna, Waltershausen visited Iceland, and subsequently published Physisch-geographische Skizze von Island (1847), Über die vulkanischen Gesteine in Sizilien und Island (1853), and Geologischer Atlas von Island (1853). Meanwhile he was appointed professor of mineralogy and geology at Göttingen, and held this post for about thirty years, until his death.

Did you know

Colour image of Io's trailing hemisphere, highlighting the large red ring around the volcano Pele on Io

Volcanoes topics

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Core topics: Volcano  • Volcanology  • Igneous petrology  • Lava  • Magma  • Decade Volcanoes  • List of volcanoes  • Plate tectonics  • Hotspot

Types of volcanoes: Fissure vent  • Shield volcano  • Lava dome  • Cinder cone  • Stratovolcano  • Supervolcano  • Submarine volcano  • Subglacial volcano  • Mud volcano

Types of eruptions: (Overview)  • Strombolian  • Vulcanian  • Peléan  • Hawaiian  • Surtseyan  • Plinian  • Submarine  • Subglacial  • Phreatic

Related portals

Selected picture

Credit: Mila Zinkova

The small town of Ortahisar in Cappadocia, Turkey, the area is covered in soft volcanic rock, which villagers have carved out to form houses, monasteries, and other structures.

Selected quote

"Is this volcano active?"

— Tourist on Mount Etna, after being reprimanded for camping out at the base of a dangerous volcanic vent, 2000.

Project collaboration

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The current Project collaboration is Mount Shasta.

The project collaboration is a drive to improve our coverage of an important volcano-related topic. Once the article has been improved significantly, a new collaboration is chosen. Please improve the article any way you can.




What you can do

Things you can do
  • Add the {{WikiProject Volcanoes}} message box to talk pages of articles within the scope of this project, including appropriate assessments, if needed.
  • Add appropriate volcano type categories to articles, and verify the accuracy of any existing categories. See the section "Categorization" below.
  • Add {{infobox mountain}} to articles if needed and missing, and add volcano-related fields to existing infoboxes if these are missing.
  • Expand volcano articles which are stubs, especially by adding photos and (most importantly) proper references.
  • Help improve articles related to Hawaiian and Canadian volcanism by joining the Hawaiian and Canadian workgroups.
  • Improve some of the project's most visible articles.

Featured work and other approved content

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Featured articles: 1980 eruption of Mount St. Helens  • 2007–2008 Nazko earthquakes  • Amchitka  • Armero tragedy  • Craters of the Moon National Monument and Preserve  • Cerro Azul (Chile volcano)  • David A. Johnston  • Enceladus (moon)  • Geology of the Lassen volcanic area  • Io (moon)  • Loihi Seamount  • Mauna Kea  • Mauna Loa  • Metacomet Ridge  • Mono-Inyo Craters  • Mount Cayley volcanic field  • Mount St. Helens  • Mount Tambora  • Nevado del Ruiz  • Surtsey  • The Volcano (British Columbia)  • Triton (moon)  • Upper and Lower Table Rock  • Volcanism on Io  • Volcano (South Park)  • Yellowstone National Park

Featured lists: List of volcanoes in Indonesia  • List of volcanoes in the Hawaiian – Emperor seamount chain  • List of largest volcanic eruptions

Featured pictures: There are currently 43 volcano-related Featured pictures. A full gallery can be seen here.

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Good articles: Abyssal plain  • Amak Volcano  • Anahim hotspot  • Axial Seamount  • Ben Nevis  • Bowie Seamount  • Crater Lake  • Davidson Seamount  • Ferdinandea  • Gareloi Volcano  • Geyser  • Glacier Peak  • Hawaii hotspot  • Hualālai  • Kohala (mountain)  • Lake Toba  • Minoan eruption  • Mount Adams (Washington)  • Mount Bailey  • Mount Baker  • Mount Cleveland (Alaska)  • Mount Edziza volcanic complex  • Mount Garibaldi  • Mount Hood  • Mount Kenya  • Mount Rainier  • Mount Redoubt  • Mount Tehama  • Mount Thielsen  • Mount Vesuvius  • Peter I Island  • Roxy Ann Peak  • Rùm  • Sakurajima  • Sangay  • Silverthrone Caldera  • Staffa  • Types of volcanic eruptions  • Volcanic ash  • Weh Island  • Wells Gray-Clearwater volcanic field  • Yamsay Mountain

Valued pictures: A gallery of volcano-related valued pictures can be seen here.

Associated Wikimedia

The following Wikimedia Foundation sister projects provide more on this subject:






Learning resources

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