A large crater formed by collapse or subsidence of the ground surface following a great eruption. During a typical caldera-forming eruption, the magma chamber is partially emptied and large amounts of ash and pyroclastic debris are extruded.
Large, circular to elongate, volcanic collapse depressions that form from the rapid extrusion of magma form a shallow subterranean magma chamber. In general, the diameter of a caldera is much greater than any of its individual volcanic vents (Williams and McBirney, 1979, p. 207).
A caldera is a large, usually circular depression at the summit of a volcano formed when magma is withdrawn or erupted from a shallow underground magma reservoir. The removal of large volumes of magma may result in loss of structural support for the overlying rock, thereby leading to collapse of the ground and formation of a large depression. Calderas are different from craters, which are smaller, circular depressions created primarily by explosive excavation of rock during eruptions.
Photograph by M. Williams, National Park Service, 1977.
Aniakchak Caldera, pictured here, formed during an enormous explosive eruption that expelled more than 50 km3 of magma about 3,450 years ago. The caldera is 10 km in diameter and 500-1,000 m deep. Subsequent eruptions formed domes, cinder cones, and explosion pits on the caldera floor.
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At least 1,299 episodes of unrest have occurred at 138 calderas greater than 5 km in diameter during historical time.
In a typical year some form of unrest (earthquakes, ground deformation, change in fumarole activity, or eruptions) occurs at about 18 large calderas worldwide, and eruptions occur within or near at least five of them.
The largest eruption of the 20th century from the Novarupta vent in the Valley of 10,000 Smokes of Alaska, ejected about 12 km3 of magma and resulted in the formation of a caldera 3 km across. Amazingly, the caldera collapse didn't occur at the eruption vent, but 10 km away at Katmai, a stratovolcano! Apparently magma drained away from Katmai's magma reservoir to Novarupta's erupting vent.
Yellowstone National Park consists of three enormous calderas that erupted about 2, 1.2, and 0.6 million years ago. The most recent caldera is 45 km across and 75 km long!
Caldera-forming eruptions are the largest eruptions on Earth. For example, the Fish Canyon eruption in southwestern Colorado (United States) about 28 million years ago erupted more than 5,000 km3 of magma from La Garita caldera. That's enough magma to bury the entire state of California to a depth of nearly 12 m!

Glossary of volcanic terms. - University of Wisconsin Oshkosh. . 2001.

Look at other dictionaries:

  • Caldera — steht für: einen vulkanischen Krater, siehe Caldera (Krater) Caldera, Namen: geographische Objekte: Departamento La Caldera, Provinz Salta, Argentinien Caldera (Costa Rica) Stadt in Costa Rica Caldera (Chile) Stadt in Chile La Caldera, Stadt in… …   Deutsch Wikipedia

  • CALDERA — ou CALDEIRA Grande dépression volcanique plus ou moins circulaire; le diamètre d’une caldera peut atteindre 25 kilomètres sur Terre (la plus grande caldera connue dans le système solaire semble être celle d’Olympus Mons, sur Mars, avec un… …   Encyclopédie Universelle

  • Caldera — Saltar a navegación, búsqueda Caldera se refiere a: La caldera, una máquina industrial que sirve para producir calor para mover una turbina u otros usos. La caldera es un componente de un sistema de calefaccion y para producir agua caliente… …   Wikipedia Español

  • caldera — sustantivo femenino 1. Recipiente metálico cerrado en el que se calienta agua para producir energía: la caldera de la calefacción, la caldera de una locomotora, la caldera de un barco, una caldera de gas, una caldera de carbón, una caldera a… …   Diccionario Salamanca de la Lengua Española

  • caldera — (Del lat. caldarĭa). 1. f. Recipiente de metal, grande y semiesférico, que sirve comúnmente para poner a calentar o cocer algo dentro de él. 2. Recipiente metálico dotado de una fuente de calor, donde se calienta el agua que circula por los tubos …   Diccionario de la lengua española

  • caldera — 1865, cavity on the summit of a volcano, from Sp. caldera cauldron, kettle, from L. caldarium, caldarius pertaining to warming, from calidus warm, hot (see CALORIE (Cf. calorie)) …   Etymology dictionary

  • Caldēra — Caldēra, 1) Stadt in der Provinz Atacama der südamerikanischen Republik Chile an der gleichnamigen Bai, wichtiger Hafen, Eisenbahn nach Copiapo (Hauptstadt der Provinz Atacama), lebhafter Handel; rasch aufblühend, 1843 nur 800 Ew., 1855 bereits… …   Pierer's Universal-Lexikon

  • Caldēra [1] — Caldēra (span.), Kesseltal (s. Barranco und Vulkane) …   Meyers Großes Konversations-Lexikon

  • Caldēra [2] — Caldēra, Hafenstadt in der chilen. Provinz Atacama, an der Ingelsbai, mit dem 82 km entfernten Copiapó durch Eisenbahn verbunden, in öder Sandgegend, aber mit sicherm, durch zwei Molen geschütztem Hafen und (1885) 2129 Einw. Die Ausfuhr besteht… …   Meyers Großes Konversations-Lexikon

  • Caldera — Caldēra (span., »Kessel«), eine durch Kratereinsturz entstandene Einsenkung; bes. auf der Insel Palma …   Kleines Konversations-Lexikon

  • Caldera [2] — Caldēra, Hafenort in der chilen. Prov. Atacama, am Stillen Ozean, (1895) 1878 E …   Kleines Konversations-Lexikon

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