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Portal:Volcanoes

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The Volcanoes portal

Sabancaya volcano, Peru in 2017

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.

Earth's volcanoes occur because its crust is broken into 17 major, rigid tectonic plates that float on a hotter, softer layer in its mantle. Therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging, and most are found underwater. For example, a mid-oceanic 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, e.g., in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande Rift in North America. This type of volcanism falls under the umbrella of "plate hypothesis" volcanism. Volcanism away from plate boundaries has also been explained as mantle plumes. These so-called "hotspots", for example Hawaii, are postulated to arise from upwelling diapirs with magma from the core–mantle boundary, 3,000 km deep in the Earth. Volcanoes are usually not created where two tectonic plates slide past one another.

Erupting volcanoes can pose many hazards, not only in the immediate vicinity of the eruption. One such hazard is that volcanic ash can be a threat to aircraft, in particular those with jet engines where ash particles can be melted by the high operating temperature; the melted particles then adhere to the turbine blades and alter their shape, disrupting the operation of the turbine. Large eruptions can affect temperature as ash and droplets of sulfuric acid obscure the sun and cool the Earth's lower atmosphere (or troposphere); however, they also absorb heat radiated from the Earth, thereby warming the upper atmosphere (or stratosphere). Historically, volcanic winters have caused catastrophic famines.

Selected article

Eruptions in the Lassen volcanic area in the last 70,000 years. Circle shows base of Mt Tehama. See timeline image
The geology of the Lassen volcanic area presents a record of sedimentation and volcanic activity in the area in and around Lassen Volcanic National Park in Northern California, U.S.. The park is located in the southernmost part of the Cascade Mountain Range in the Pacific Northwest region of the United States. Oceanic tectonic plates have plunged below the North American Plate in this part of North America for hundreds of millions of years. Heat from these subducting plates have fed scores of volcanoes in California, Oregon, Washington and British Columbia over at least the past 30 million years (see Geology of the Pacific Northwest) and is also responsible for activities in the Lassen volcanic area. Between 3 and 4 million years ago, volcanic-derived mud flows called lahars streamed down several major mountains that included nearby but now extinct Mount Yana and Mount Maidu to become the Tuscan Formation. Basaltic and later andesitic to dacitic flows of lava covered increasingly larger areas of this formation to eventually form the lava plateau that the park sits on. About 600,000 years ago, Mount Tehama started to rise as a stratovolcano in the southwestern corner of the park, eventually reaching an estimated 11,000 feet (3,350 m) in height. Following a series of eruptions approximately 350,000 years ago, its cone collapsed into itself to form a two-mile (3 km) wide caldera.


Selected biography

Howel Williams (1898-1980) was a noted American geologist and volcanologist. He was born of Welsh parents in Liverpool, England, on October 12, 1898. He received a BA in geography in 1923 and an MA in archaeology in 1924 from Liverpool University. He studied geology at the Imperial College of Science and Technology in London. In 1926 he moved to the University of California at Berkeley in 1926. In 1928 he was awarded the degree of D.Sc. from the University of Liverpool and published his first papers on the geology of various California volcanic regions.

He published many studies on the volcanoes of California, but is most noted for his "The Geology of Crater Lake National Park" in which he recognized the nature of the collapse of the crater and extended the work to develop the principles of volcanic caldera formation. He did extensive early work on the geology of Central America (often sketch-mapping from the windows of second-class buses), and of the Galapagos Islands. In Latin America, Williams put to good use his early background in archeology. For instance, he used petrographic techniques to trace the origin of stone used in the giant Olmec sculptures of La Venta, Tabasco Mexico.

Did you know

Orogeny is a mountain building event in which a section of the Earth's crust is folded and deformed by compression

Stereoscopic map of Sotra Facula

Volcanoes topics

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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

Related portals

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Wide view of the Olympus Mons aureole, escarpment and caldera
Credit: NASA

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 / 18; -133. 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.

Selected quote

"No one told us we needed a gas mask."

— Tourist visiting the highly active Ambrym volcano, South West Pacific.


Project collaboration

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The current Project collaboration is Mount Shasta.

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.

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  • Add the {{WikiProject Volcanoes}} message box to talk pages of articles within the scope of this project, including appropriate assessments, if needed.
  • Add appropriate volcano type categories to articles, and verify the accuracy of any existing categories. See the section "Categorization" below.
  • Add {{infobox mountain}} to articles if needed and missing, and add volcano-related fields to existing infoboxes if these are missing.
  • Expand volcano articles which are stubs, especially by adding photos and (most importantly) proper references.
  • Help improve articles related to Hawaiian and Canadian volcanism by joining the Hawaiian and Canadian workgroups.
  • Improve some of the project's most visible articles.


Featured work and other approved content

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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)  • 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 43 volcano-related Featured pictures. A full gallery can be seen here.

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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

Valued pictures: A gallery of volcano-related valued pictures can be seen here.

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