Portal:Volcanoes
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. Lua error in package.lua at line 80: module 'Module:Box-header/colours' not found. The 1980 eruption of Mount St. Helens, a volcano located in Washington state, in the United States, was a major volcanic eruption. The eruption was the most significant to occur in the contiguous 48 U.S. states (VEI = 5, 0.3 cu mi, 1.2 km3 of material erupted), in terms of power and volume of material released, since the 1915 eruption of California's Lassen Peak. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the mountain that created a huge bulge and a fracture system on Mount St. Helens' north slope. An earthquake at 8:32 a.m. on May 18, 1980, caused the entire weakened north face to slide away, suddenly exposing the partly molten, gas- and steam-rich rock in the volcano to lower pressure. The rock responded by exploding into a very hot mix of pulverized lava and older rock that sped toward Spirit Lake so fast that it quickly passed the avalanching north face. A volcanic ash column rose high into the atmosphere and deposited ash in 11 U.S. states. At the same time, snow, ice, and several entire glaciers on the mountain melted, forming a series of large lahars (volcanic mudslides) that reached as far as the Columbia River, nearly fifty miles (eighty kilometers) to the south. Less severe outbursts continued into the next day only to be followed by other large but not as destructive eruptions later in 1980.Lua error in package.lua at line 80: module 'Module:Box-header/colours' not found. David Alexander Johnston (December 18, 1949 – May 18, 1980) was a volcanologist with the United States Geological Survey (USGS); he was killed by the 1980 eruption of the Mount St. Helens volcano in Washington. He was killed while manning an observation post about 6 miles (10 km) from the volcano on the morning of May 18, 1980. He was the first to report the eruption, transmitting the famous message "Vancouver! Vancouver! This is it!" before being swept away by the lateral blast created by the collapse of the mountain's north flank. Ham radio operator Jerry Martin observed the lateral blast overtaking Johnston's camp. Though Johnston's remains have never been found, remnants of his USGS trailer were found by state highway workers in 1993.Johnston was the only geologist with the USGS to correctly predict the nature of the eruption. The official USGS prediction was that the volcano would experience a conventional vertical column eruption, while Johnston (who had been doing extensive research on the volcano and the geologic forces at play within and around it) had proposed that the blast would be lateral and originate from the bulge which he had observed developing on the side of the mountain. Lua error in package.lua at line 80: module 'Module:Box-header/colours' not found.
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 Template:/box-footer
Lua error in package.lua at line 80: module 'Module:Box-header/colours' not found. Semeru is the tallest mountain on the island of Java and one of its most active volcanoes. Known also as Mahameru (Great Mountain), it is very steep and rises abruptly above the coastal plains of eastern Java. Maars containing crater lakes have formed along a line through the summit. Semeru lies at the south end of the Tengger Volcanic Complex. Lua error in package.lua at line 80: module 'Module:Box-header/colours' not found. <templatestyles src="Template:Blockquote/styles.css" />
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. Template:/box-footer ► Atolls
{{Wikipedia:WikiProject Volcanoes/Open tasks}} Template:/box-footer 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 {{Wikipedia:WikiProject Volcanoes/Content|FP}} 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. Template:/box-footer The following Wikimedia sister projects provide more on this subject:
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