Portal:Volcanoes
The Volcanoes portal
On Earth, volcanoes are most often found where tectonic plates are diverging or 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 can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary, 3,000 kilometers (1,900 mi) deep within Earth. This results in hotspot volcanism, of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide past one another.
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 winters which have caused catastrophic famines.
Other planets besides Earth have volcanoes. For example, volcanoes are very numerous on Venus. 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.'
This article mainly covers volcanoes on Earth. See § Volcanoes on other celestial bodies and Cryovolcano for more information. (Full article...)
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Surtsey ("Surtr's island" in Icelandic, Icelandic pronunciation: [ˈsʏr̥(t)sˌeiː] ) is an uninhabited volcanic island located in the Vestmannaeyjar archipelago off the southern coast of Iceland. At Surtsey is the southernmost point of Iceland. It was formed in a volcanic eruption which began 130 metres (430 feet) below sea level, and reached the surface on 14 November 1963. The eruption lasted until 5 June 1967, when the island reached its maximum size of 2.7 km2 (1.0 sq mi). Since then, wave erosion has caused the island to steadily diminish in size: , its surface area was 1.3 km2 (0.50 sq mi). The most recent survey (2007) shows the island's maximum elevation at 155 m (509 ft) above sea level.
The new island was named after Surtr, a fire jötunn or giant from Norse mythology. It was intensively studied by volcanologists during its eruption, and afterwards by botanists and other biologists as life forms gradually colonised the originally barren island. The undersea vents that produced Surtsey are part of the Vestmannaeyjar submarine volcanic system, part of the fissure of the sea floor called the Mid-Atlantic Ridge. Vestmannaeyjar also produced the famous eruption of Eldfell on the island of Heimaey in 1973. The eruption that created Surtsey also created a few other small islands along this volcanic chain, such as Jólnir and other, unnamed peaks. Most of these eroded away fairly quickly. It is estimated that Surtsey will remain above sea level until at least the year 2100. (Full article...)Did you know
- ... that the 60 million years old Carmelo Formation (pictured) is made out of thousands of layers of volcanic pebbles, sandstone and mudstone with fossils?
- ... that one of the activities that are possible at the Nevado de Toluca National Park is scuba diving in the two volcanic crater lakes?
- ... that the Popocatépetl volcano occasionally dumps ash on the municipality of Ozumba, Mexico?
- ... that in August 2001, the Galileo spacecraft flew through the sulfur dioxide gas plume of the Ionian volcano Thor?
- ... that the Garibaldi Volcanic Belt in southwestern British Columbia is the site of Canada's largest recorded Holocene explosive eruption 2,350 years ago at the Mount Meager massif?
- ... that most of the recent volcanism in New Zealand has been along the line of the Taupo Volcanic Zone and the Kermadec island arc?
- ... that the asphalt volcano is a rare submarine volcano composed of asphalt and erupting petroleum and methane instead of lava?
- ... that eruptions from Mahogany Mountain, a caldera volcano, produced rock formations in Leslie Gulch over 15 million years ago?
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Selected biography -
Barry Voight (/vɔɪt/; born 1937) is an American geologist, volcanologist, author, and engineer. After earning his Ph.D. at Columbia University, Voight worked as a professor of geology at several universities, including Pennsylvania State University, where he taught from 1964 until his retirement in 2005. He remains an emeritus professor there and still conducts research, focusing on rock mechanics, plate tectonics, disaster prevention, and geotechnical engineering.
In April 1980, Voight's publications on landslides, avalanches, and other mass movements attracted the attention of Rocky Crandell of the United States Geological Survey (USGS), who asked him to look at a growing bulge on the Mount St. Helens volcano in the state of Washington. Voight foresaw the collapse of the mountain's north flank as well as a powerful eruption. His predictions came true when St. Helens erupted in May 1980; Voight was then hired by the USGS to investigate the debris avalanche that initiated the eruption. After his work at Mount St. Helens brought him international recognition, Voight continued researching and guiding monitoring efforts at several active volcanoes throughout his career, including Nevado del Ruiz in Colombia, Mount Merapi in Indonesia, and Soufrière Hills, a volcano on the Caribbean island of Montserrat. For his research, publications, and disaster prevention work as a volcanologist and engineer, Voight has been honored with numerous awards, appointments, and medals. (Full article...)Selected picture
An arching fountain of pāhoehoe lava, approximately 10 m (33 ft) high, issuing from a spatter cone of Pu‘u Kahaualea, Hawaii. Pāhoehoe is basaltic lava that has a smooth, billowy, undulating, or ropy surface. These surface features are due to the movement of very fluid lava under a congealing surface crust. Pāhoehoe lavas typically have a temperature of 1100°C–1200°C.
Selected quote
"We'll just look at you. If you looked scared then we'll panic."
— Discovery channel crew, talking to volcanologist John Seach during filming at Yasur Volcano, 2000.
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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) • Kamaʻehuakanaloa 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.
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.
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