Portal:Volcanoes
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...)
Ubinas is an active stratovolcano in the Moquegua Region of southern Peru, approximately 60 kilometres (37 mi) east of the city of Arequipa. Part of the Central Volcanic Zone of the Andes, it rises 5,672 metres (18,609 ft) above sea level. The volcano's summit is cut by a 1.4-kilometre-wide (0.87 mi) and 150-metre-deep (490 ft) caldera, which itself contains a smaller crater. Below the summit, Ubinas has the shape of an upwards-steepening cone with a prominent notch on the southern side. The gently sloping lower part of the volcano is also known as Ubinas I and the steeper upper part as Ubinas II; they represent different stages in the volcano's geological history.
The most active volcano in Peru, Ubinas has a history of small to moderate explosive eruptions as well as a few larger eruptions, such as in 1667, along with persistent degassing and ash emissions. Activity at the volcano began in the Pleistocene epoch, and led to the growth of the current mountain in two phases. Among the recent eruptions was the 2006–2007 event, which produced eruption columns and led to ash fall in the region, resulting in health issues and evacuations. During the most recent activity, from 2013 to 2017, a lava flow formed inside the crater, and further ash falls led to renewed evacuations of surrounding towns. Ubinas is monitored by the Peruvian geological service INGEMMET, which has published a volcano hazard map for Ubinas and regular volcanic activity reports. (Full article...)- ... that the Cameroon line of volcanoes is 1,000 kilometres (620 mi) long, and includes Mount Oku, the second highest mountain in Cameroon?
- ... that there was intense volcanic activity in Uruguay during the Cretaceous period about 130 million years ago?
- ... that seismologist Fusakichi Omori (pictured) of the Imperial University of Tokyo, who mapped the effects of the 1906 San Francisco earthquake, later designed and donated the equipment to found the Hawaiian Volcano Observatory?
- ... that Heart Peaks in northern British Columbia, Canada, is the third largest volcano in the Northern Cordilleran Volcanic Province?
- ... that Green Seamount, an underwater volcano, could have taken up to 260,000 years to reach its present height?
- ... that both the Pole Creek Wilderness and North Fork Owyhee Wilderness have some of the largest concentrations of sheer-walled volcanic rhyolite and basalt canyons in the western United States?
- ... that volcanologist Harry Glicken was saved from the 1980 eruption of Mount St. Helens due to a scheduling conflict, only to die in the eruption of Mount Unzen in 1991?
- ...that the eruption of Pu'u 'O'o added 544 acres (2.2 km²) of land to the island of Hawaii?
David Alexander Johnston (December 18, 1949 – May 18, 1980) was an American United States Geological Survey (USGS) volcanologist who was killed by the 1980 eruption of Mount St. Helens in the U.S. state of Washington. A principal scientist on the USGS monitoring team, Johnston was killed in the eruption while manning an observation post six miles (10 km) away on the morning of May 18, 1980. He was the first to report the eruption, transmitting "Vancouver! Vancouver! This is it!" before he was swept away by a lateral blast; despite a thorough search, Johnston's body was never found, but state highway workers discovered remnants of his USGS trailer in 1993.
Johnston's career took him across the United States, where he studied the Augustine Volcano in Alaska, the San Juan volcanic field in Colorado, and long-extinct volcanoes in Michigan. Johnston was a meticulous and talented scientist, known for his analyses of volcanic gases and their relationship to eruptions. This, along with his enthusiasm and positive attitude, made him liked and respected by many co-workers. After his death, other scientists lauded his character, both verbally and in dedications and letters. Johnston felt scientists must do what is necessary, including taking risks, to help protect the public from natural disasters. His work, and that of fellow USGS scientists, convinced authorities to close Mount St. Helens to the public before the 1980 eruption. They maintained the closure despite heavy pressure to re-open the area; their work saved thousands of lives. His story became intertwined with the popular image of volcanic eruptions and their threat to society, and a part of volcanology's history. To date, Johnston, along with his mentee Harry Glicken, is one of two American volcanologists known to have died in a volcanic eruption.
Following his death, Johnston was commemorated in several ways, including a memorial fund established in his name at the University of Washington to fund graduate-level research. Two volcano observatories were established and named after him: one in Vancouver, Washington, and another on the ridge where he died. Johnston's life and death are featured in several documentaries, films, docudramas and books. A biography of his life, A Hero on Mount St. Helens: The Life and Legacy of David A. Johnston, was published 2019. (Full article...)Olympus Mons is the highest known volcano and mountain in the Solar System. It is located on the planet Mars at approximately 18°N 133°W / 18°N 133°W. Since the late 19th century—well before space probes confirmed its identity as a mountain—Olympus Mons was known to astronomers as the albedo feature, Nix Olympica ("Snows of Olympus"), although its mountainous nature was suspected.
"No one told us we needed a gas mask."
— Tourist visiting the highly active Ambrym volcano, South West Pacific.
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
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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
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