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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. More about volcanoes... The Mount Cayley volcanic field is a remote volcanic zone on the South Coast of British Columbia, Canada, stretching 31 km (19 mi) from the Pemberton Icefield to the Squamish River. It forms a segment of the Garibaldi Volcanic Belt, the Canadian portion of the Cascade Volcanic Arc, which extends from Northern California to southwestern British Columbia. Most of the Cayley volcanoes were formed during periods of volcanism under sheets of glacial ice throughout the last glacial period. These subglacial eruptions formed steep, flat-topped volcanoes and subglacial lava domes, most of which have been entirely exposed by deglaciation. However, at least two volcanoes predate the last glacial period and both are highly eroded. The field gets its name from Mount Cayley, the largest and most persistent volcano, located at the southern end of the Powder Mountain Icefield. This icefield covers much of the central portion of the volcanic field and is one of the several glacial fields in the Pacific Ranges of the Coast Mountains. 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. Regal Mountain ...that Regal Mountain (pictured), an eroded stratovolcano in the Wrangell Mountains, is the third-highest thirteener (a peak between 13,000 and 14,000 feet in elevation) in Alaska? ...that Canadian scientist Bill Mathews was a pioneer in the study of subglacial eruptions and volcano-ice interactions in North America? ...that thermal vent ecosystems have been discovered in the Aegean Sea, in the caldera of Kolumbo underwater volcano? ...that Hawaii's Chain of Craters Road has been blocked repeatedly by lava flows from Kīlauea volcano since it was built in 1928? ...that Halemaʻumaʻu crater in Hawaii Volcanoes National Park erupted explosively on March 19 2008 for the first time since 1924? ... that Bowie Seamount on the British Columbia Coast of Canada is one of the most biologically rich submarine volcanoes on Earth and was an active volcanic island throughout the last glacial period? ... that the Lava River Cave in Newberry National Volcanic Monument is the longest known uncollapsed lava tube in Oregon, U.S.? ... that the early pre-Columbian site of Xochitecatl in Mexico was abandoned for centuries after the Popocatepetl volcano erupted around 150 AD? 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 Portal:Seamounts Earth sciences Seamounts Geography Atmospheric sciences 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. "This ground is hot enough to cook the Sunday roast!" — John Seach, remarking on his boots melting whilst on the slope of Lopevi Volcano, 2000 {{Wikipedia:WikiProject Volcanoes/Collaboration}} 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 WikiProject Volcanoes WikiProject Seamounts WikiProject Mountains ▼ Volcanoes ► Lists of volcanoes ► Volcanoes by continent ► Volcanoes by country ► Atolls ► Complex volcanoes ► Decade Volcanoes ► Diatremes ► Hotspot volcanoes ► Volcanic islands ► Lava domes ► Pyroclastic shields ► Ridge volcanoes ► Rift volcanoes ► Shield volcanoes ► Stratovolcanoes ► Subduction volcanoes ► Subglacial volcanoes ► Submarine volcanoes ► Supervolcanoes ► Volcanic belts ► Volcanic calderas ► Volcanic cones ► Volcanic craters ► Volcanic fields ► Volcanic Seven Summits ▼ Volcanology ► Hydrothermal vents ► Volcanic belts ► Volcanic eruption types ► Volcanic events ► Volcanic rocks ► Volcanoes {{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: What are portals? List of portals Featured portals