Caldeira

A will caldeira (Portuguese will caldeira , which means cauldron ) is a term of Volcanologie which indicates a crater of ic origin Volcan, of form circular or elliptic and measuring of one kilometer and half with several tens of kilometers broad.

Largest will caldeira known is that of the Toba, formed there is 73 000 years, and which is in the island of Sumatra in Indonesia. It is hundred kilometers long and thirty kilometers broad.

Many will caldeiras fill of water by collecting rivers or by reccueillant rainwater and thus form lakes like that of Crater Lake (the United States) or of the Askja (Iceland). Others are partially open on the sea and form bays or gulfs as with Santorin (Greece), with Rabaul (New Guinea-News-Guinea), with the Champs Phlégréens (Italy), etc

Origin

Will caldeiras can be formed by explosion or subsidence (collapse) of a volcano, generally at the time of an explosive eruption.

In the case of a formation by explosion, the pressure in the magmatic Chambre is sufficient to generate an explosion whose breath will carry whole or part of the volcano which is above.

In the case of a formation by subsidence, the draining of the magmatic room during the eruption can lead the volcano to crumble there. This phenomenon in the case of occurs an important draining of a large magmatic room. The effusive volcanos can sometimes present the large ones will caldeiras of subsidence being formed during various eruptions.

Some examples of will caldeira

Askja (Iceland) ;
Aso (Japan) ;
Caldera de Taburiente (Canary islands, Spain) ;
Cabeço Gordo (island of Faial, the Azores, Portugal) ;
Tired Cañadas on the mount Teide (Canary islands, Spain) ;
the archipelago of Santorin (Aegean Sea, Greece) ;
Crater Lake on the Mount Mazama (National park of Crater Lake, Oregon, the United States) ;
the Enclosure of the Piton of the Furnace (Island of the Meeting, France) ;
Long Valley (California, the United States) ;
Mount Tambora (Indonesia) ;
Lake Toba (Indonesia) ;
Lake Towada (Japan) ;
Tengger (Indonesia) ;
Valle Large (New Mexico, the United States) ;
Yellowstone Caldera (Wyoming, the United States) ;
Newberry Caldera (Oregon, the United States) ;
Ngorongoro Caldera (Tanzania) ;
Rabaul (New Guinea-News-Guinea).

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