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.|
Sources of Information:
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.
Sand box models/analogue caldera models
(Based mostly on the work of V. Acocella)
What are they?
Sand box models can provide excellent scaled analogues of collapsed super volcanoes (calderas) and can be used to simulate the collapse of the roof above a magma chamber (fig. 1)
Why do we use them?
They are very useful because by simulating collapses you can see features in 3-D and compare them with real examples, a very clear picture of the caldera geometry can be made!
How can you make a sand box model?
To make a box sand model you will need:
A wood made box, with a hole in the base or the side wall (fig. 2)
2 or 3 different color sand, layered on 0.25 cm thick or less (to see better the layers!)
An up warding rigid sphere or a balloon connected to an air machine, to simulate the magma chamber (fig. 2)
Types of experiments
There are three primary types of experiments:
- Inflation ones, which simulate overpressure
- Deflation ones, which simulate underpressure
- Polycyclic ones, which simulate over and underpressure
Overpressure: Are those where the sphere rises or the balloon inflates, both simulating a magma chamber growth (doming or resurgence):
Underpressure: Are those experiments where the balloon is deflated and mimics the collapse behavior in calderas
Polycyclic: Are those experiments where inflation is followed by deflation and a consecutive inflation of the balloon, producing a cyclic rim and radial fractures:
What do we see?
In the case of underpressure collapse (the more realistic case and common among World’s calderas) we can expect the following set of features:
- An outer inward dipping set of normal ring faults
- An internal gently to steeply outward set of inverse ring faults
- A central depression surrounded by the caldera wall
Real examples of these geometries include:
Long Valley Caldera (USA)
Valles Caldera (USA)
Campi Flegrei (Italy)
How do we use these results to understand calderas?
The results bring important issues related to location of faults, their development in time and their geometry. This knowledge could be used to understand geometries on old eroded calderas (cauldrons), “younger” calderas <10000 ka or very new (active) ones like Yellowstone.
Acocella V, 2007, Understanding caldera structure and development: An overview of analogue models compared to natural calderas: Earth-Science Reviews 85 (2007) 125–160. http://dx.doi.org.proxy.library.oregonstate.edu/10.1016/j.earscirev.2007.08.004
The classification of the five main calderas types (downsag, piston, funnel, piecemeal, trapdoor) do not examine: (a) the structure of calderas (particularly the nature of the caldera's bounding faults); and (b) how this is achieved (including the genetic relationships among the five caldera types). The first part of this study reviews these experiments, which induce collapse as a result of underpressure or overpressure within the chamber analogue. The experiments simulating overpressure display consistent results, but the experimental depressions require an exceptional amount of doming, seldom observed in nature, to form; therefore, these experiments are not appropriate to understand the structure and formation of most natural calderas. The experiments simulating underpressure reveal a consistent scenario for caldera structure and development, regardless of their different boundary conditions. These show that complete collapse proceeds through four main stages, proportional to the amount of subsidence, progressively characterized by: (1) downsag; (2) reverse ring fault; (3) peripheral downsag; (4) peripheral normal ring fault. The second part of this study verifies the possibility that these latter calderas constitute a suitable analogue to nature and consists of a comprehensive comparison of the underpressure experiments to natural calderas. The general relationship between the evolutionary stage of a caldera and its d/s (diameter/subsidence) ratio allows such quantification, with stage 1 calderas characterized by d/sN40, stage 2 by 18bd/sb40, stage 3 by 14bd/sb18 and stage 4 by d/sb14. The four stages adequately explain the architecture and development of the established caldera end-members along a continuum, where one or more end-members (downsag, piston, funnel, piecemeal, trapdoor) may correspond to a specific stage.
Troll et al., 2002, Cyclic caldera collapse: Piston or piecemeal subsidence? Field and experimental evidence: Geology 2002; 30; 135-138
The authors used field data and experiments scaled to the island of Gran Canaria to clarify the structural, temporal, and genetic relationship of peripheral faults to the central caldera. The experimental setup comprises a cone of medium-grained sand in which a rubber balloon was repeatedly inflated and deflated. Balloon inflation resulted in updoming and a dominantly radial fault pattern, whereas balloon deflation caused piecemeal caldera collapse and a concentric peripheral fault arrangement on the edifice flanks. A complex interplay of repeated inflation and deflation cycles of the experimental magma chamber is found to explain the peripheral fault system of the Tejada caldera on Gran Canaria and offers insight into the structure of the caldera floor and the mechanisms acting in multicycle caldera volcanoes
- URL: http://volcanoes.usgs.gov/lvo/publications/maps/index.php
- URL: http://geoinfo.nmt.edu/faq/volcanoes/valles_caldera-lg.jpg
- URL: http://www.tightrope.it/monten/sezcf1.jpg
This page was created as part of the OSU Volcanology 2010 class by Rodrigo Iriartea.
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.
Aso volcano has produced more explosive eruptions than any other volcano in the world.
Aso is a caldera about 12 miles (20 km) in diameter. Of the numerous stratovolcanoes and cinder cones inside the caldera only Naka-dake has been active in historic time. The first documented eruption in Japan was at Naka-dake in 553. Since then, Naka-dake (shown above) has erupted 167 times. The most recent eruption ended in 1993. Most eruptions of Naka-dake are small to moderate in size. Most are simple explosions that produce ash or blocks. Aso has not produced lava flows in historic time. Only 8 eruptions have caused fatalities. Most fatalities are tourists on the rim of the cone. Note people sledding and skiing in the foreground. Photograph courtesy of and copyrighted by Paul J. Buklarewicz.
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.
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)