The Volcanoes portal
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. The process that forms volcanoes is called volcanism.
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, the Wells Gray-Clearwater volcanic field, and the 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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Limalok (formerly known as Harrie or Harriet) is a Cretaceous-Paleocene guyot/tablemount in the southeastern Marshall Islands, one of a number of seamounts (a type of underwater volcanic mountain) in the Pacific Ocean. It was probably formed by a volcanic hotspot in present-day French Polynesia. Limalok lies southeast of Mili Atoll and Knox Atoll, which rise above sea level, and is joined to each of them through a volcanic ridge. It is located at a depth of 1,255 metres (4,117 ft) and has a summit platform with an area of 636 square kilometres (246 sq mi).
Limalok is formed by basaltic rocks and was probably a shield volcano at first; the Macdonald, Rarotonga, Rurutu and Society hotspots may have been involved in its formation. After volcanic activity ceased, the volcano was eroded and thereby flattened, and a carbonate platform formed on it during the Paleocene and Eocene. These carbonates were chiefly produced by red algae, forming an atoll or atoll-like structure with reefs. (Full article...)
Did you know
- ... that the decomposing skeleton of a right whale was found on the submarine volcano Patton Seamount (pictured)?
- ... that Suiyo Seamount, a seamount near Japan, was thought to be extinct until a hydrothermal event in 1991 was brought to light?
- ... that death can be found living on hell's half acre?
- ... that the 27-million-year-old Cobb Seamount is so heavily encrusted in sea life that no bare rock surface has been found in dives?
- ... that parts of the shield volcano Fumarole Butte were once covered by Lake Bonneville?
- ... that the Temagami Greenstone Belt in Ontario was the site of the largest deposit of nearly pure chalcopyrite ever discovered in Canada?
- ... that the Makushin Volcano is one of the most active volcanoes of Alaska?
General images
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TOMS sulfur dioxide from the June 15, 1991 eruption of Mount Pinatubo. (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)
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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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Diagram showing the scale of VEI correlation with total ejecta volume (from Types of volcanic eruptions)
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VEI and ejecta volume correlation (from Timeline of volcanism on Earth)
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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)
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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)
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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)
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A gentle, or effusive, volcanic eruption, in which liquid material (lava) gently flows from a vent, in this case in south-eastern Hawai’i island (from Volcanism)
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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)
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Sulfur dioxide emissions by volcanoes. Mount Pinatubo: 20 million tons of sulfur dioxide. (from Timeline of volcanism on Earth)
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Some features of volcanism found in Earth's crust (from Volcanism)
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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)
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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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Satellite measurements of ash and aerosol emissions from Mount Pinatubo. (from Timeline of volcanism on Earth)
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2016 eruption of Mount Sinabung (from Types of volcanic eruptions)
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Phreatic explosion captured at the Main Crater of Taal Volcano in January 2020, from an installed IP camera of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) monitoring the volcano. (from Decade Volcanoes)
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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)
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Distribution of selected hotspots. The numbers in the figure are related to the listed hotspots on Hotspot (geology). (from Timeline of volcanism on Earth)
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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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Lahar flows from the 1985 eruption of Nevado del Ruiz, which totally destroyed Armero in Colombia (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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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)
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Diagrammatic representation of a plume on Enceladus (from Volcanism)
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The final eruptions in the creation of Banks Peninsula in New Zealand occurred about 9 million years ago. (from Timeline of volcanism on Earth)
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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)
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Eruption of mud at Dashgil mud volcano in Gobustan, Azerbaijan (from Volcanism)
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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)
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Mount Lamington following the devastating 1951 eruption (from Types of volcanic eruptions)
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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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MLO transmission ratio - Solar radiation reduction due to volcanic eruptions (from Timeline of volcanism on Earth)
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The lava spine that developed after the 1902 eruption of Mount Pelée (from Types of volcanic eruptions)
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Colima Volcano eruption column, December 2016 (from Decade Volcanoes)
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Cross section diagram of Earth showing some settings for volcanism on the planet (from Volcanism)
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21 April 1990 eruptive column from Redoubt Volcano, as viewed to the west from the Kenai Peninsula (from Types of volcanic eruptions)
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NASA, Global Dimming - El Chichon, VEI 5; Pinatubo, VEI 6. (from Timeline of volcanism on Earth)
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Lava-flooded craters and large expanses of smooth volcanic plains on Mercury (from List of extraterrestrial volcanoes)
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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)
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Selected biography -
Berend George Escher (4 April 1885 – 11 October 1967) 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
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Aerial view of Mount Kilimanjaro, the highest peak in Africa and the fourth highest of the Seven Summits. The volcano consists of three distinctive volcanic cones; of which the Kibo cone, pictured, is highest.
Selected quote
"El enemigo sigue ahí. (The enemy is still there)"
— Sergio Galilea, intendant of the Los Lagos Region, Chile, speaking of the Chaitén Volcano on the first anniversary of its eruption, 2 May 2009
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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) • 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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