Stati Uniti · Caldera
Mount Aniakchak
Aniakchak
- Tipo
- Caldera
- Altitudine
- 1341 m
- Ultima eruzione
- 1931
- Tipo
- Caldera
- Paese
- Stati Uniti
- Regione
- Nord America / Alaska Peninsula Volcanic Arc
- Altitudine
- 1341 m
- Coordinate
- 56.880, -158.170
- Ultima eruzione
- 1931
- Contesto tettonico
- Zona di subduzione / Crosta continentale (> 25 km)
- Forma vulcanica
- Caldera
- Roccia principale
- Andesite / Andesite basaltica
Sintesi geologica
One of the most dramatic calderas of the Aleutian arc, the 10-km-wide Aniakchak caldera formed around 3,400 years ago during a voluminous eruption in which pyroclastic flows traveled more than 50 km N to the Bering Sea and also reached the Pacific Ocean to the south. At least 40 explosive eruptions have been documented during the past 10,000 years, making it the most active volcano of the eastern Aleutian arc. A dominantly andesitic pre-caldera volcano was constructed above basement Mesozoic and Tertiary sedimentary rocks that are exposed in the caldera walls to elevations of about 610 m. The ice-free caldera floor contains many pyroclastic cones, tuff cones, maars, and lava domes. Surprise Lake on the NE side drains through The Gates, a steep-walled breach on the east side of the 1-km-high caldera rim that was the site of catastrophic draining of a once larger lake about 1850 years BP. Vent Mountain and Half Cone are two long-lived vents on the south-central and NW caldera floor, respectively. The first and only confirmed historical eruption took place in 1931 from vents on the west and SW caldera floor.
Sintesi da Wikipedia
Riassunto in ingleseMount Aniakchak is a volcano on the western Alaska Peninsula. Part of the Aleutian Volcanic Arc, it was formed by the subduction of the oceanic Pacific Plate under the North American Plate. Aniakchak is a 10 kilometers (6.2 mi) wide caldera with a break to the northeast. The caldera contains Surprise Lake and many volcanic cones, maars and craters, including Vent Mountain. The volcano has erupted mainly calc-alkaline rocks ranging from basalt to rhyolite.
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Storia delle eruzioni
17 registrateGlossarioCronologia dettagliata
- 1942VEI ?Metodo non indicato1942-07-02 – fine sconosciuta
- 1931VEI 4Osservata1931-05-01 – 1931-06-13West and SW caldera floor
- 1540 (±100 anni)VEI 4Stima geologica1540 – fine sconosciutaNW & S caldera floor (Half Cone, Vent Mtn)
- 1470 (±20 anni)VEI ?Stima geologica1470 – fine sconosciutaSE caldera floor (New Cone)
- 1370 (±55 anni)VEI ?Stima geologica1370 – fine sconosciutaNW caldera floor (Half Cone)
- 1280 (±145 anni)VEI ?Stima geologica1280 – fine sconosciutaNW caldera floor (Half Cone)
- 1190 (±30 anni)VEI ?Stima geologica1190 – fine sconosciutaNW caldera floor (Half Cone)
- 1120 (±80 anni)VEI ?Stima geologica1120 – fine sconosciutaEast-central caldera (Surprise Cone)
- 1050VEI ?Stima geologica1050 – fine sconosciutaVent Mtn and other vents?
- 700 (±250 anni)VEI 0Stima geologica700 – fine sconosciutaS & NW caldera floor (Vent Mtn & Half Cone)
- 460VEI ?Stima geologica460 – fine sconosciuta
- 200 (±255 anni)VEI ?Stima geologica200 – fine sconosciutaNorthern & western caldera floor
- 370 a.C. (±210 anni)VEI ?Stima geologica370 a.C. – fine sconosciuta
- 1645 a.C. (±10 anni)VEI 6Stima geologica1645 a.C. – fine sconosciuta
- 2550 a.C. (±500 anni)VEI ?Stima geologica2550 a.C. – fine sconosciuta
- 5930 a.C. (±240 anni)VEI ?Stima geologica5930 a.C. – fine sconosciuta
- 6300 a.C. (±1250 anni)VEI 6Stima geologica6300 a.C. – fine sconosciuta
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