This article relies largely or entirely on a single source . (March 2020)
A monogenetic volcanic field is a type of volcanic field consisting of a group of small monogenetic volcanoes, each of which erupts only once, as opposed to polygenetic volcanoes, which erupt repeatedly over a period of time. Many monogenetic volcanoes are cinder cones, often with lava flows, such as Parícutin in the Michoacán-Guanajuato volcanic field, which erupted from 1943 to 1952. Some monogenetic volcanoes are small lava shields, such as Rangitoto Island in the Auckland volcanic field. Other monogenetic volcanoes are tuff rings or maars. A monogenetic field typically contains between ten and a hundred volcanoes. The Michoacán-Guanajuato field in Mexico contains more than a thousand volcanoes and is much larger than usual.
Monogenetic fields occur only where the magma supply to the volcano is low or where vents are not close enough or large enough to develop plumbing systems for continuous feeding of magma. Monogenetic volcanic fields can provide snapshots of the underlying region beneath the surface, and may be useful in studying the generation of magma and the composition of the mantle since the single eruption produced would match that of the chamber from which it erupted.
Examples of monogenetic volcanic fields:
A caldera is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber/reservoir in a volcanic eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is lost. The ground surface then collapses downward into the emptied or partially emptied magma chamber, leaving a massive depression at the surface. Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Only seven caldera-forming collapses are known to have occurred since 1900, most recently at Bárðarbunga volcano, Iceland in 2014.
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 Ring of Fire is a major area in the basin of the Pacific Ocean where many earthquakes and volcanic eruptions occur. In a large 40,000 km (25,000 mi) horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and plate movements. It has 452 volcanoes.
Rangitoto Island is a volcanic island in the Hauraki Gulf near Auckland, New Zealand. The 5.5 km (3.4 mi) wide island is a symmetrical shield volcano cone, reaching a height of 260 m (850 ft). Rangitoto is the youngest and largest of the approximately 50 volcanoes of the Auckland volcanic field, having formed in an eruption about 600 years ago, and covering an area of 2,311 ha. It is separated from the mainland of Auckland's North Shore by the Rangitoto Channel. Since World War II, it has been linked by a causeway to the much older, non-volcanic Motutapu Island.
Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and size of the fragments ejected during the eruption. Types of volcanic cones include stratocones, spatter cones, tuff cones, and cinder cones.
A shield volcano is a type of volcano usually composed almost entirely of fluid lava flows. It is named for its low profile, resembling a warrior's shield lying on the ground. This is caused by the highly fluid lava erupted, which travels farther than lava erupted from a stratovolcano, and results in the steady accumulation of broad sheets of lava, building up the shield volcano's distinctive form.
Parícutin is a cinder cone volcano located in the Mexican state of Michoacán, near the city of Uruapan and about 322 kilometers (200 mi) west of Mexico City. The volcano surged suddenly from the cornfield of local farmer Dionisio Pulido in 1943, attracting both popular and scientific attention.
The Auckland volcanic field is an area of monogenetic volcanoes covered by much of the metropolitan area of Auckland, New Zealand's largest city, located in the North Island. The approximately 53 volcanoes in the field have produced a diverse array of maars, tuff rings, scoria cones, and lava flows. No volcano has erupted twice, but eruptions lasted for various periods ranging from a few weeks to several years. The field is fuelled entirely by basaltic magma, unlike the explosive subduction-driven volcanism in the central North Island, such as at Mount Ruapehu and Lake Taupo. The field is currently dormant, but could become active again.
The Trans-Mexican Volcanic Belt, also known as the Transvolcanic Belt and locally as the Sierra Nevada, is a volcanic belt that covers central-southern Mexico. Several of its highest peaks have snow all year long, and during clear weather, they are visible to a large percentage of those who live on the many high plateaus from which these volcanoes rise.
El Jorullo is a cinder cone volcano in Michoacán, central Mexico, on the southwest slope of the central plateau, 33 miles southeast of Uruapan in an area known as the Michoacán-Guanajuato volcanic field. It is about 6 miles (10 km) east-northeast of La Huacana. Its current elevation is 4,360 ft (1,329 m). El Jorullo has four smaller cinder cones which have grown from its flanks. The vents of El Jorullo are aligned in a northeast to southwest direction. Lava from these vents cover nine square km around the volcano. Later eruptions produced lavas that had higher silica contents making them thicker than the earlier basalts and basaltic andesite lavas. El Jorullo's crater is about 1,300 by 1,640 feet wide and 490 feet (150 m) deep.
A Strombolian eruption is a type of volcanic eruption with relatively mild blasts, having a volcanic explosivity index of about 1 to 3. Strombolian eruptions consist of ejection of incandescent cinders, lapilli, and lava bombs, to altitudes of tens to a few hundreds of metres. The eruptions are small to medium in volume, with sporadic violence. This type of eruption is named for the Italian volcano Stromboli.
Nevado de Longaví is a volcano in the Andes of central Chile. The 3,242 m (10,636 ft) high volcano lies in the Linares Province, which is part of the Maule Region. It features a summit crater and several parasitic vents. The volcano is constructed principally from lava flows. Two collapses of the edifice have carved collapse scars into the volcano, one on the eastern slope known as Lomas Limpias and another on the southwestern slope known as Los Bueye. The volcano features a glacier and the Achibueno and Blanco rivers originate on the mountain.
The Milbanke Sound Group, also called the Milbanke Sound Cones, is an enigmatic group of five small basaltic volcanoes in the Kitimat Ranges of the Coast Mountains in British Columbia, Canada. Named for Milbanke Sound, this volcanic group straddles on at least four small islands, including Swindle, Price, Lady Douglas and Lake Island. Not much is known about this group of volcanoes and they remain undated. However, they all likely formed in the past 10,000 years after the last glacial period as evidenced by a small amount of erosion. The age of the most recent volcanic activity is also unknown. Most of the Milbanke Sound Cones are covered by mature forest. Kitasu Hill and Helmet Peak are the only two cones that are officially named.
Several types of volcanic eruptions—during which lava, tephra, and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series.
A cinder cone is a steep conical hill of loose pyroclastic fragments, such as either volcanic clinkers, volcanic ash, or cinder that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions or lava fountains from a single, typically cylindrical, vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as either cinders, clinkers, or scoria around the vent to form a cone that often is symmetrical; with slopes between 30–40°; and a nearly circular ground plan. Most cinder cones have a bowl-shaped crater at the summit.
Volcanology of New Zealand is the scientific study of volcanoes and volcanic phenomena in New Zealand. Volcanism has been responsible for many of the country's geographical features, especially in the North Island and the country's outlying islands.
The Wells Gray-Clearwater volcanic field, also called the Clearwater Cone Group, is a potentially active monogenetic volcanic field in east-central British Columbia, Canada, located approximately 130 km (81 mi) north of Kamloops. It is situated in the Cariboo Mountains of the Columbia Mountains and on the Quesnel and Shuswap Highlands. As a monogenetic volcanic field, it is a place with numerous small basaltic volcanoes and extensive lava flows.
Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption, usually at temperatures from 700 to 1,200 °C. The structures resulting from subsequent solidification and cooling are also sometimes described as lava. The molten rock is formed in the interior of some planets, including Earth, and some of their satellites, though such material located below the crust is referred to by other terms.
Michoacán–Guanajuato volcanic field is located in central Mexico. It is a volcanic field that takes the form of a large cinder cone field, with numerous shield volcanoes and maars.
Cerros Negros de Jama is a monogenetic volcanic group in the Andes, Jujuy Province, Argentina. The group is formed by about four well preserved scoria cones with lava fields and one isolated lava field, constructed on Ordovician marine sediments and dacitic lavas from the adjacent Cerro Bayo de Archibarca volcano. These cones are aligned submeridionally with a fault system in the ground. The lavas and associated dykes have porphyritic appearance and variable morphology. The lavas show no evidence of ponding in crustal magma chambers, suggesting that the large volatile content of the magma was sufficient to quickly transport it through the crust. Magma temperatures have been estimated at higher than 1,000 °C (1,830 °F).
|This volcanology article is a stub. You can help Wikipedia by expanding it.|