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Dakataua caldera is 10 by 13 km and has a volume of 75 cubic km. The most recent episode of caldera collapse was probably about 1,150 years ago. Mount Makalia, an andesite volcano, and other volcanoes that have erupted along the outer caldera rim partially fill the caldera. The freshwater lake is at least 120 m deep. The most recent eruption was at Mount Makalia in 1890. The eruption produced three cinder cones and lava flows.
Simplified map of Dakataua caldera from Newhall and Dzurisin (1988).
|Space Shuttle photo STS028-0090-0084 taken on July 13, 1989. The photo looks south along the Talasea Peninsula. Dakataua caldera forms the north end of the peninsula. The peninsula is about 50 km long.|
Johnson, R.W., 1976, Late Cainozoic volcanism and plate tectonics at the southern margin of the Bismarck Sea, Papua New Guinea, in Johnson, R.W., ed., 1976, Volcanism in Australia: Amsterdam, Elsevier, p. 101-116.
Lowder, G.G., and Carmichael, I.S.E., 1970, The volcanoes and caldera of Talasea, New Britain: geology and petrology: Geol. Soc. America Bull., v. 81, p. 17-38.
Newhall, C.G., and Dzurisin, D., 1988, Historical unrest at large calderas of the world: U.S. Geological Survey Bulletin 1855, p. 210-213.
Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.
(By R. Iriartea, 2010)
The 200 cu km Atka volcano is the largest volcanic center in the central Aleutians. A central shield volcano and caldera is ringed by 7 or 8 satellitic volcanoes.
This view, from near Atka village, shows 1533-m-high Korovin volcano, the highest and northernmost of three Holocene stratovolcanoes of the Atka volcanic complex.
Korovin has been the most active during historical time, but Sarichef and Kliuchef volcanoes may also have had historical eruptions.
Photo by James Dickson, 1986 (courtesy of John Reeder, Alaska Div. Geology Geophysical Surveys).
Lake Atitlan (center), San Pedro (left), Toliman (right background), and Atitlan (right foreground). View is to the northeast.
Image Credit: Steve O'Meara of Volcano Watch International.
Volcanic activity began in the Lake Atitlan area about 11-12 million years ago. The present-day stratovolcanoes and caldera represent the most recent of four periods of volcano growth and caldera collapse. This recent period of activity began about 1.8 million years ago. A large explosive eruption about 84,000 years ago formed the most recent Atitlan caldera.
Lake Atitlan fills part of the caldera.
Aniakchak is a caldera about 6.2 miles (10 km) across. Large pyroclastic flows surround the mountain. Eruptions inside the caldera have formed many vents, including tuff cones and a 3,280 ft. (1,000 m) high cinder cone. About 10 lava flows have occurred since the caldera's formation 3,400 years ago, none of which were outside the caldera rim.
Aniakchak does not have a symmetrical shape in that it is steeper on its northwest slope than on the its southeast slope that faces its high caldera wall. Aniakchak's most recent activity occurred in 1931.
Sources of Information:
Rowland, Scott K., et al, "Preliminary ERS-1 Observations of Alaskan and Aleutian Volcanoes," Planetary Geosciences Dept. of Geology and Geophysics, School of Ocean and Earth Science and Technology, pp. 4-5, Feb. 22, 1993.
Wood, Charles A. and Kienle, Jurgen, "Volcanoes of North America United States and Canada," Cambridge University Press, 347pp., 1990.
General map of Ambrym showing the main volcanic features (caldera, cones, maars, and fissures). Ambrym is the most voluminous active volcano in Vanuatu. Marum and Benbow are post-caldera cones. The caldera is similar in size to calderas associated with large Plinian eruptions. From Robin and others (1993).
Ambrym Island is a large shield volcano with a caldera. The caldera formed in about 50 A.D. with an eruption of VEI 6. It is also a very active volcano with 48 eruptions since 1774. Most of these eruptions are at cones inside of a caldera (5.5 by 7.5 miles; 9 by 12 km).The eruptions are explosive and usually from a central vent, There have been a few flank eruptions. Fifteen erupts produced lava flows. Ten eruptions involved a lava lake. There were fatalities in two eruptions at Ambrym. In 1894, six people were killed by volcanic bombs and four people were overtaken by lava flows. In 1913, 21 people were killed during an explosive eruption. Acid rainfall in 1979 burned some of the inhabitants. Local water supplies were contaminated and had a pH of 5.2-5.5.
Me-Akan is a stratovolcano in the depression and the only active vent. Me-Akan has erupted at least 15 times since about 1800. Eruptions prior to 1955 were weak. The 1955 eruption was phreatic and explosive. The most recent eruption was in 1988. Although it was phreatic, like most eruptions at Me-Akan, it lasted just over a month. Most eruptions at Me-Akan last less than one day.
Distant view of Akan, a group of stratovolcanoes, that lies within a shallow depression. Me-Akan, the active vent, is the steaming volcano on the left. Some volcanologists think the shallow depression is a caldera.
Image credit: Paul J. Buklarewicz.
Summit of Me-Akun.
Image credit: Mike Lyvers.
The scenic lake-filled Akademia Nauk caldera is one of three volcanoes constructed within the mid-Pleistocene, 15-km-wide Polovinka caldera.
Two nested calderas, 5 x 4 km Odnoboky and 3 x 5 km Akademia Nauk (also known as Karymsky Lake or Academii Nauk), were formed during the late Pleistocene, the latter about 30,000 years ago. Eruptive products varied from initial basaltic-andesite lava flows to late-stage rhyodacitic lava domes.
The first historical eruption from Akademia Nauk did not take place until January 2, 1996, when a brief, day-long explosive eruption of unusual basaltic and rhyolitic composition occurred from vents beneath the NNW part of the caldera lake near Karymsky maar.
(Description courtesy of the SI/USGS GVP)