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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On March 27, 1980, a series of volcanic explosions and pyroclastic flows began at Mount St. Helens in Skamania County, Washington, United States. A series of phreatic blasts occurred from the summit and escalated until a major explosive eruption took place on May 18, 1980, at 8:32 am. The eruption, which had a volcanic explosivity index of 5, was the first to occur in the contiguous United States since the much smaller 1915 eruption of Lassen Peak in California. It has often been declared the most disastrous volcanic eruption in U.S. history.
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 volcano that created a large bulge and a fracture system on the mountain's north slope. An earthquake at 8:32:11 am PDT (UTC−7) on May 18, 1980, caused the entire weakened north face to slide away, a sector collapse which was the largest subaerial landslide in recorded history. This allowed the partly molten rock, rich in high-pressure gas and steam, to suddenly explode northward toward Spirit Lake in a hot mix of lava and pulverized older rock, overtaking the landslide. An eruption column rose 80,000 feet (24 km; 15 mi) into the atmosphere and deposited ash in 11 U.S. states and various Canadian provinces. At the same time, snow, ice, and several entire glaciers on the volcano melted, forming a series of large lahars (volcanic mudslides) that reached as far as the Columbia River, nearly 50 miles (80 km) to the southwest. Less severe outbursts continued into the next day, only to be followed by other large, but not as destructive, eruptions later that year. The thermal energy released during the eruption was equal to 26 megatons of TNT. (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?
General images
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Diagram of a Plinian eruption. (key: 1. Ash plume 2. Magma conduit 3. Volcanic ash rain 4. Layers of lava and ash 5. Stratum 6. Magma chamber) Click for larger version. (from Types of volcanic eruptions) -
The final eruptions in the creation of Banks Peninsula in New Zealand occurred about 9 million years ago. (from Timeline of volcanism on Earth) -
A diagram of a Subglacial eruption. (key: 1. Water vapor cloud 2. Crater lake 3. Ice 4. Layers of lava and ash 5. Stratum 6. Pillow lava 7. Magma conduit 8. Magma chamber 9. Dike) Click for larger version. (from Types of volcanic eruptions) -
Lahar flows from the 1985 eruption of Nevado del Ruiz, which totally destroyed Armero in Colombia (from Types of volcanic eruptions) -
Diagram of a Strombolian eruption. (key: 1. Ash plume 2. Lapilli 3. Volcanic ash rain 4. Lava fountain 5. Volcanic bomb 6. Lava flow 7. Layers of lava and ash 8. Stratum 9. Dike 10. Magma conduit 11. Magma chamber 12. Sill) Click for larger version. (from Types of volcanic eruptions) -
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2016 eruption of Mount Sinabung (from Types of volcanic eruptions) -
VEI and ejecta volume correlation (from Timeline of volcanism on Earth) -
Diagrammatic representation of a plume on Enceladus (from Volcanism) -
Satellite animation of the initial ash plume and shockwave of the 2022 Hunga Tonga–Hunga Ha’apai eruption and tsunami. The massive explosive eruption was hundreds of times more powerful than the atomic bomb dropped on Hiroshima. (from Volcanism) -
Lava-flooded craters and large expanses of smooth volcanic plains on Mercury (from List of extraterrestrial volcanoes) -
Some features of volcanism found in Earth's crust (from Volcanism) -
Satellite measurements of ash and aerosol emissions from Mount Pinatubo. (from Timeline of volcanism on Earth) -
Diagram of a Submarine eruption. (key: 1. Water vapor cloud 2. Water 3. Stratum 4. Lava flow 5. Magma conduit 6. Magma chamber 7. Dike 8. Pillow lava) Click to enlarge. (from Types of volcanic eruptions) -
21 April 1990 eruptive column from Redoubt Volcano, as viewed to the west from the Kenai Peninsula (from Types of volcanic eruptions) -
MLO transmission ratio - Solar radiation reduction due to volcanic eruptions (from Timeline of volcanism on Earth) -
Colima Volcano eruption column, December 2016 (from Decade Volcanoes) -
A gentle, or effusive, volcanic eruption, in which liquid material (lava) flows from a vent, in this case in south-eastern Hawai’i island (from Volcanism) -
Diagram of a Hawaiian eruption. (key: 1. Ash plume 2. Lava fountain 3. Crater 4. Lava lake 5. Fumaroles 6. Lava flow 7. Layers of lava and ash 8. Stratum 9. Sill 10. Magma conduit 11. Magma chamber 12. Dike) Click for larger version. (from Types of volcanic eruptions) -
Diagram of a Surtseyan eruption. (key: 1. Water vapor cloud 2. Compressed ash 3. Crater 4. Water 5. Layers of lava and ash 6. Stratum 7. Magma conduit 8. Magma chamber 9. Dike) Click for larger version. (from Types of volcanic eruptions) -
Distribution of selected hotspots. The numbers in the figure are related to the listed hotspots on Hotspot (geology). (from Timeline of volcanism on Earth) -
Diagram showing the scale of VEI correlation with total ejecta volume (from Types of volcanic eruptions)
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An example of the lava arcs formed during Strombolian activity. This image is of Stromboli itself. (from Types of volcanic eruptions) -
Some of the eruptive structures formed during volcanic activity (counterclockwise): a Plinian eruption column, Hawaiian pahoehoe flows, and a lava arc from a Strombolian eruption (from Types of volcanic eruptions) -
Sarychev Peak: the sulphur dioxide cloud generated by the eruption on June 12, 2009 (in Dobson units). (from Timeline of volcanism on Earth) -
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Diagram of a phreatic eruption. (key: 1. Water vapor cloud 2. Magma conduit 3. Layers of lava and ash 4. Stratum 5. Water table 6. Explosion 7. Magma chamber) (from Types of volcanic eruptions) -
Sulfur dioxide emissions by volcanoes. Mount Pinatubo: 20 million tons of sulfur dioxide. (from Timeline of volcanism on Earth) -
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Cross section diagram of Earth showing some settings for volcanism on the planet (from Volcanism) -
Diagram of a Vulcanian eruption. (key: 1. Ash plume 2. Lapilli 3. Lava fountain 4. Volcanic ash rain 5. Volcanic bomb 6. Lava flow 7. Layers of lava and ash 8. Stratum 9. Sill 10. Magma conduit 11. Magma chamber 12. Dike) Click for larger version. (from Types of volcanic eruptions) -
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Mount Lamington following the devastating 1951 eruption (from Types of volcanic eruptions) -
Phreatic explosion captured at the Main Crater of Taal Volcano. Photo taken from the installed IP camera of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) monitoring the volcano. (from Decade Volcanoes) -
The lava spine that developed after the 1902 eruption of Mount Pelée (from Types of volcanic eruptions) -
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The high initial temperatures of silicate lavas mean that they emit visible light before cooling. (from Volcanism) -
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NASA, Global Dimming - El Chichon, VEI 5; Pinatubo, VEI 6. (from Timeline of volcanism on Earth) -
TOMS sulfur dioxide from the June 15, 1991 eruption of Mount Pinatubo. (from Timeline of volcanism on Earth) -
Location of Mount Pinatubo, showing area over which ash from the 1991 eruption fell. (from Timeline of volcanism on Earth) -
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A major eruption of Gran Canaria took place around 14 million years ago. (from Timeline of volcanism on Earth) -
Diagram of Peléan eruption. (key: 1. Ash plume 2. Volcanic ash rain 3. Lava dome 4. Volcanic bomb 5. Pyroclastic flow 6. Layers of lava and ash 7. Stratum 8. Magma conduit 9. Magma chamber 10. Dike) Click for larger version. (from Types of volcanic eruptions) -
Olympus Mons (Latin, "Mount Olympus"), located on the planet Mars, is the tallest known mountain in the Solar System. (from Volcanism)
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An October 2002 eruption of Mount Etna, a volcano on the Italian island of Sicily, as seen from the International Space Station. Etna is the largest of Italy's three active volcanoes and one of the most active in the world. This eruption, one of Etna's most vigorous in years, was triggered by a series of earthquakes. Ashfall was reported as far away as Libya, 600 km (373 mi) to the south.
Selected quote
"We'll just look at you. If you looked scared then we'll panic."
— Discovery channel crew, talking to volcanologist John Seach during filming at Yasur Volcano, 2000.
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Featured work and other approved content
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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