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A caldera is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is lost. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface. Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur each century, the formation of a caldera is a rare event, occurring only a few times per century. Only seven caldera-forming collapses are known to have occurred between 1911 and 2016. More recently, a caldera collapse occurred at Kīlauea, Hawaii in 2018.
Masaya is a caldera located in Masaya, Nicaragua, 20 km south of the capital Managua. It is Nicaragua's first and largest national park, and one of 78 protected areas of Nicaragua. The complex volcano is composed of a nested set of calderas and craters, the largest of which is Las Sierras shield volcano and caldera. Within this caldera lies a sub-vent, which is Masaya Volcano sensu stricto. The vent is a shield type composing of basaltic lavas and tephras and includes a summit crater. This hosts Masaya caldera, formed 2,500 years ago by an 8-km³ basaltic ignimbrite eruption. Inside this caldera a new basaltic complex has grown from eruptions mainly on a semi-circular set of vents that include the Masaya and Nindiri cones. The latter host the pit craters of Masaya, Santiago, Nindiri and San Pedro. Observations in the walls of the pit craters indicate that there have been several episodes of cone and pit crater formation.
Maipo is a stratovolcano in the Andes, lying on the border between Argentina and Chile. It is located 90 km (56 mi) south of Tupungato and about 100 km (62 mi) southeast of Santiago. It has a symmetrical, conical volcanic shape, and is among the southernmost 5,000 metre peaks in the Andes.
The Yellowstone hotspot is a volcanic hotspot in the United States responsible for large scale volcanism in Idaho, Montana, Nevada, Oregon, and Wyoming, formed as the North American tectonic plate moved over it. It formed the eastern Snake River Plain through a succession of caldera-forming eruptions. The resulting calderas include the Island Park Caldera, Henry's Fork Caldera, and the Bruneau-Jarbidge caldera. The hotspot currently lies under the Yellowstone Caldera. The hotspot's most recent caldera-forming supereruption, known as the Lava Creek Eruption, took place 640,000 years ago and created the Lava Creek Tuff, and the most recent Yellowstone Caldera. The Yellowstone hotspot is one of a few volcanic hotspots underlying the North American tectonic plate; another example is the Anahim hotspot.
Mount Silverthrone, officially named Silverthrone Mountain, is a mountain in the Pacific Ranges of the Coast Mountains of British Columbia, Canada, located over 320 km (200 mi) northwest of the city of Vancouver and about 50 km (30 mi) west of Mount Waddington, British Columbia, Canada. It is the highest peak in the Ha-Iltzuk Icefield, which is the largest icefield in the Coast Mountains south of the Alaska Panhandle.
The Pemberton Volcanic Belt is an eroded Oligocene-Miocene volcanic belt at a low angle near the Mount Meager massif, British Columbia, Canada. The Garibaldi and Pemberton volcanic belts appear to merge into a single belt, although the Pemberton is older than the Garibaldi Volcanic Belt. The Pemberton Volcanic Belt is one of the geological formations comprising the Canadian Cascade Arc. It formed as a result of subduction of the former Farallon Plate.
The Bennett Lake Volcanic Complex (BLVC) is a huge 50-million-year-old extinct caldera complex that spans across the British Columbia-Yukon border in Canada. It is located near the western end of the West Arm of Bennett Lake. The caldera complex is surrounded by granitic rocks containing pendants.
The Skukum Group is a 55-million-year-old volcanic group in northern British Columbia and southern Yukon, Canada. It consists of discrete calderas in a linear range from the south end of Atlin Lake to Bennett Lake, then to Aishihik Lake. The cluster of rocks crowds the Mount Skukum gold deposit southwest of Whitehorse. One of the calderas within the group is the Bennett Lake Volcanic Complex.
Sturgeon Lake Caldera is a large extinct caldera complex in Kenora District of Northwestern Ontario, Canada. It is one of the world's best preserved mineralized Neoarchean caldera complexes, containing well-preserved mafic-intermediate pillow lavas, pillow breccias, hyaloclastite and peperites, submarine lava domes and dome-associated breccia deposits. The complex is some 2.7 billion years old with a minimum strike length of 30 km (19 mi).
Machmell River Cone is a cinder cone in the Silverthrone Caldera complex in the Pacific Ranges section of the Coast Mountains in British Columbia, Canada. It is believed the volcano last erupted during the Holocene, making it one of the most recent eruptions of the Silverthrone complex.
The Clisbako Caldera Complex is a large dissected caldera complex in the Chilcotin Group and Anahim Volcanic Belt in central British Columbia, Canada. It has a diameter of 60 km (37 mi) and is composed mainly of Eocene felsic and mafic volcanic rocks. Rocks within the caldera range in composition from basalt to rhyolite, the complex is located in the well known ring of fire.
The Blake River Megacaldera Complex is a giant subaqueous caldera cluster or a nested caldera system that spans across the Ontario–Quebec border in Canada.
The New Senator Caldera is a large Archean caldera complex within the heart of the Blake River Megacaldera Complex, Quebec, Canada. It has a diameter of 15-30 kilometers and is made of thick massive mafic sequences. The caldera complex has inferred to be a subaqueous lava lake during the early stages of the caldera's development. Gabbro sills represent lava lakes, which are common in mafic summit calderas. These subaqueous lava lakes are large units with a change in grain size from coarse to fine grained and a hyaloclastite top. The Kiwanis (Norands) intrusion, a high-level synvolcanic magma chamber, intrudes felsic rocks, and is in turn cross-cut by basaltic dikes and sills.
The Noranda Caldera is a well-known large subaqueous Archean caldera complex within the Blake River Megacaldera Complex, Quebec, Canada. The caldera contains a 7-to-9-km-thick succession of bimodal mafic-felsic tholeiitic to calc-alkaline volcanic rocks which were erupted during five major series of volcanic activity.
The Misema Caldera is a 2,704-2,707 million year old caldera in Ontario and Quebec, Canada.
The Silverthrone Caldera is a potentially active caldera complex in southwestern British Columbia, Canada, located over 350 kilometres (220 mi) northwest of the city of Vancouver and about 50 kilometres (31 mi) west of Mount Waddington in the Pacific Ranges of the Coast Mountains. The caldera is one of the largest of the few calderas in western Canada, measuring about 30 kilometres (19 mi) long (north-south) and 20 kilometres (12 mi) wide (east-west). Mount Silverthrone, an eroded lava dome on the caldera's northern flank that is 2,864 metres (9,396 ft) high, may be the highest volcano in Canada.
Akan Volcanic Complex is a volcanic group of volcanoes that grew out of the Akan caldera. It is located within Akan National Park, about 50 km Northwest of Kushiro in eastern Hokkaidō, Japan.
The Springdale Caldera is a large Early Silurian caldera in west-central Newfoundland, Canada. It is at least 60 km (37 mi) long and 35 km (22 mi) wide, covering an area of more than 2,000 km2 (770 sq mi). It is one of the few calderas in Newfoundland that form a large Silurian age volcanic field. Basalt, andesite, rhyolite, pyroclastic rocks, debris flows, breccias and red sandstone are present at the Springdale Caldera.
La Pacana is a Miocene age caldera in northern Chile's Antofagasta Region. Part of the Central Volcanic Zone of the Andes, it is part of the Altiplano-Puna volcanic complex, a major caldera and silicic ignimbrite volcanic field. This volcanic field is located in remote regions at the Zapaleri tripoint between Chile, Bolivia and Argentina.
The Hunter Mine caldera is a caldera complex in the North Volcanic Zone of the Abitibi greenstone belt in Ontario and Quebec, Canada. It is located at the eastern end of Lake Abitibi.
References
- ↑ "Geology". American University of Beirut. Archived from the original on 2008-01-07. Retrieved 2019-03-07.
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