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A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and most 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 in the 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 the Earth's troposphere. Historically, large volcanic eruptions have been followed by volcanic winters which have caused catastrophic famines. (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. After 69 years of dormancy, the volcano's eruption caught nearby towns unaware, even though the government had received warnings from volcanological organizations to evacuate the area after the detection of 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 kilometers per hour (30 miles per hour). 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 tragedy, 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 Volcano (pictured) in northwestern British Columbia is the youngest known volcano in Canada, and its last eruption likely took place only 150 years ago?
- ... that the Geology of the Northland Region, New Zealand, includes exotic seafloor rocks, an extinct volcanic arc, and a massive tombolo?
- ... that volcanic eruptions may have contributed to the population decline of the Pink-headed warbler?
- ... that CenSeam is an initiative to biologically sample seamounts (submarine volcanoes), of which about 100,000 exist and only 350 have received attention?
- ... that the Graveyard Seamounts are all named morbidly, with names such as Pyre Seamount, Morgue Seamount, and Zombie Seamount?
- ... that the tablemount structure of Sedlo Seamount, a seamount (submarine volcano), indicates that it used to be above the water?
- ... that observations and samplings from Jasper Seamount show that it is very similar to Hawaiian volcanoes?
- ... that South Chamorro Seamount, a submarine mud volcano near the Mariana Trench, is only the second such structure in the world to be sampled?
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Selected biography -
Berend George Escher (4 April 1885 in Gorinchem – 11 October 1967 in Arnhem) was a Dutch geologist.
Escher had a broad interest, but his research was mainly on crystallography, mineralogy and volcanology. He was a pioneer in experimental geology. He was a half-brother of the artist M.C. Escher, and had some influence on his work due to his knowledge of crystallography. M.C. Escher created a woodcut ex libris for his brother 'Beer' with a stylized image of a volcano around 1922 (Bool number 91).
Escher was the son of the civil engineer G. A. Escher, a director of the Dutch watermanagement (Rijkswaterstaat) and his first wife, Charlotte Marie Hartitzsch. Escher spent his youth in Switzerland. He studied geology at the Eidgenössische Technische Hochschule (Technical University) of Zürich, where he was a pupil of Albert Heim. He finished his studies in 1911 and returned to the Netherlands where he first became the assistant of M.E.F.T. Dubois at the University of Amsterdam and then curator of the geological collections at Delft University. In 1916 he was employed by Royal Dutch Shell in the Dutch East Indies. (Full article...)Selected picture
Io moon taken by NASA's Galileo probe. This image shows two volcanic eruptions. The one on the horizon is 140 km (87 mi) high, the other is 75 km (47 mi) high. Io is the innermost of the four Galilean moons of Jupiter. It is named after Io, one of Zeus's many love interests in Greek mythology.
Selected quote
"Do we need to bring a sleeping bag, or will the volcano keep us warm at night?"
— Documentary producer at Mount Etna, 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) • 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.
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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