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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The Armero tragedy (Spanish: Tragedia de Armero [tɾaˈxeðja ðe aɾˈmeɾo]) occurred following the eruption of the Nevado del Ruiz stratovolcano in Tolima, Colombia, on November 13, 1985. The volcano's eruption after 69 years of dormancy caught nearby towns unprepared, even though volcanological organizations had warned the government to evacuate the area after they detected volcanic activity two months earlier.
As pyroclastic flows erupted from the volcano's crater, they melted the mountain's glaciers, sending four enormous lahars (volcanically induced mudflows, landslides, and debris flows) down its slopes at 50 km/h (30 mph). The lahars picked up speed in gullies and engulfed the town of Armero, killing more than 20,000 of its almost 29,000 inhabitants. Casualties in other towns, particularly Chinchiná, brought the overall death toll to 23,000. Footage and photographs of Omayra Sánchez, a young victim of the disaster, were published around the world. Other photographs of the lahars and the impact of the disaster captured attention worldwide and led to controversy over the degree to which the Colombian government was responsible for the disaster. A banner at a mass funeral in Ibagué read, "The volcano didn't kill 22,000 people. The government killed them." (Full article...)Did you know
- ... that the volcanic chain (pictured) responsible for creating the island of Hawaii extends all the way to the Kuril–Kamchatka Trench, at the border of Russia?
- ... that Nintoku Seamount, an underwater volcano in the Hawaiian–Emperor seamount chain, is over 56.2 million years old?
- ... that volcanoes in the Puyehue Volcano complex may have produced some of the most primitive magmas in the Andes?
- ... that Pilot Rock is one of the oldest volcanic formations in the Cascade Range?
- ... that one of a series of hotels called the Volcano House, built at the edge of Kīlauea volcano since 1846, burned to the ground from a kitchen fire?
- ... that the eruption of Amak Volcano in about 2550 BCE was confirmed by tephrochronology?
- ... that the Bobrof Volcano is an uninhabited island in the Andreanof Islands, part of Alaska's Aleutian archipelago?
- ... that the closest transportation to Davidof Volcano is 199 miles (320 km) away in Adak, Alaska?
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George Julius Poulett Scrope FRS (10 March 1797 – 19 January 1876) was an English geologist and political economist as well as a Member of Parliament and magistrate for Stroud in Gloucestershire.
While an undergraduate at Cambridge, through the influence of Edward Clarke and Adam Sedgwick he became interested in mineralogy and geology. During the winter of 1816–1817 he was at Naples, and was so keenly interested in Vesuvius that he renewed his studies of the volcano in 1818; and in the following year visited Etna and the Lipari Islands. In 1821 he married the daughter and heiress of William Scrope of Castle Combe, Wiltshire, and assumed her name; and he entered the House of Commons of the United Kingdom in 1833 as MP for Stroud, retaining his seat until 1868.
Meanwhile he began to study the volcanic regions of central France in 1821, and visited the Eifel district in 1823. In 1825 he published Considerations on Volcanos, leading to the establishment of a new theory of the Earth, and in the following year was elected FRS. This earlier work was subsequently amplified and issued under the title of Volcanos (1862); an authoritative text-book of which a second edition was published ten years later. In 1827 he issued his classic Memoir on the Geology of Central France, including the Volcanic formations of Auvergne, the Velay and the Vivarais, a quarto volume illustrated by maps and plates. The substance of this was reproduced in a revised and somewhat more popular form in The Geology and Extinct Volcanos of Central France (1858). These books were the first widely published descriptions of the Chaîne des Puys, a chain of over 70 small volcanoes in the Massif Central. (Full article...)Selected picture
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Now an extinct volcano is not quite so safe a neighbour as many may suppose. Vesuvius was an extinct volcano from time immemorial till the year 63, when it suddenly broke out again, and soon after destroyed Pompeii and Herculaneum; since which time it has never again subsided into entire inactivity.
— A possible event — dangers of our planet, The National Magazine, November 1854, p. 435
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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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