A caldera is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the structural integrity of such a chamber, greatly diminishing its capacity to support its own roof, and any substrate or rock resting above. 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 over the course of a century, the formation of a caldera is a rare event, occurring only a few times within a given window of 100 years. 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.
The Ring of Fire is a tectonic belt of volcanoes and earthquakes.
Masaya is a caldera located in Masaya, Nicaragua, 20 km (12 mi) 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 (1.9 cu mi) 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.
Antofagasta de la Sierra is a volcanic field in Argentina. The main type of volcanic edifice in the area are scoria cones, it is formed by the La Laguna, Jote and Alumbrera volcanoes. The first and last of these form a sub-group which is better researched. Various dating methods have yielded ages from several million to several hundred thousand years ago, but some vents appear to be of Holocene age.
Payún Matrú is a shield volcano in the Reserva Provincial La Payunia of the Malargüe Department, south of the Mendoza Province in Argentina. It lies in the back-arc region of the Andean Volcanic Belt, and was formed by the subduction of the Nazca Plate beneath the South American Plate. Payún Matrú, along with the Llancanelo, Nevado and Salado Basin volcanic fields, form the Payenia province. It has been proposed as a World Heritage Site since 2011.
Peinado is a stratovolcano in Catamarca Province, Argentina. It consists of a volcanic cone with a summit crater, surrounded at its foot by lava flows erupted from flank vents. It began erupting about 100,000 years ago, with the last eruption about 36,800 years ago. Future eruptions are possible.
Socompa is a large stratovolcano at the border of Argentina and Chile with an elevation of 6,051 metres (19,852 ft) metres. Part of the Chilean and Argentine Andean Volcanic Belt (AVB), it is part of the Central Volcanic Zone, one of the various segments of the AVB. This part of the Andean volcanic arc begins in Peru and runs first through Bolivia and Chile, and then through Argentina and Chile, and contains about 44 active volcanoes. Socompa lies close to the pass of the same name, where the Salta-Antofagasta railway crosses the border.
Cerro Galán is a caldera in the Catamarca Province of Argentina. It is one of the largest exposed calderas in the world and forms part of the Central Volcanic Zone of the Andes, one of the three volcanic belts found in South America. One of several major caldera systems in the Central Volcanic Zone, the mountain is grouped into the Altiplano–Puna volcanic complex.
Ollagüe or Ullawi is a massive andesite stratovolcano in the Andes on the border between Bolivia and Chile, within the Antofagasta Region of Chile and the Potosi Department of Bolivia. Part of the Central Volcanic Zone of the Andes, its highest summit is 5,868 metres (19,252 ft) above sea level and features a summit crater that opens to the south. The western rim of the summit crater is formed by a compound of lava domes, the youngest of which features a vigorous fumarole that is visible from afar.
Paniri is a stratovolcano located in El Loa Province, Antofagasta Region, Chile, and near the border with Bolivia. To its northwest lie the twin volcanoes San Pedro and San Pablo, and to its southeast lies Cerro del León, from which it is separated by the huge Chao lava dome.
San Pedro is a Holocene composite volcano in northern Chile and at 6,155 metres (20,194 ft) in elevation one of the highest active volcanoes in the world. Part of the Chilean Andes' volcanic segment, it is part of the Central Volcanic Zone of the Andes, one of the four tracts of the Andean Volcanic Belt. This region of volcanism includes the world's two highest volcanoes Ojos del Salado and Llullaillaco. San Pedro, like other Andean volcanoes, was formed by the subduction of the Nazca Plate beneath the South America Plate. It has a neighbouring volcano, San Pablo, and is itself formed by two separate edifices usually known as the Old Cone and the Young Cone. These edifices are formed by rocks ranging from basaltic andesite over andesite to dacite and are emplaced on a basement formed by Miocene volcanic rocks.
Antofagasta de la Sierra is a village in Catamarca Province, Argentina. It is the head town of the Antofagasta de la Sierra Department.
Lastarria is a 5,697 metres (18,691 ft) high stratovolcano that lies on the border between Chile and Argentina. It is remote, and the surroundings are uninhabited but can be reached through an unpaved road. The volcano is part of the Central Volcanic Zone, one of the four segments of the volcanic arc of the Andes. Over a thousand volcanoes—of which about 50 are active—lie in this over 1,500 kilometres (930 mi) long chain of volcanoes, which is generated by subduction of the Nazca Plate beneath the South American Plate.
Olca-Paruma is a volcanic complex in Chile. Lying on the border between Chile and Bolivia, it is formed by an east–west alignment of volcanoes. From west to east, these are Cerro Paruma, Volcan Paruma, Olca, and Mencheca or Michincha. Aside from the mines of Ujina, Rosario, and Quebrada Blanca, the area is sparsely populated.
Tebenquicho is a volcano in Argentina.
Tocomar is a Pleistocene volcano in the Jujuy Province, Argentina. It is part of the Andean Volcanic Belt, more specifically to its sub-belt the Central Volcanic Zone. The Central Volcanic Zone consists of about 44 active volcanoes and large calderas of the Altiplano-Puna volcanic complex. Volcanism there is caused by the subduction of the Nazca Plate beneath the South America Plate in the Peru-Chile Trench. At Tocomar, volcanism is further influenced by a large fault zone, the Calama-Olacapato-El Toro fault, which runs diagonally across the volcanic arc.
Antofalla is a Miocene-Pliocene volcano in Argentina's Catamarca Province. It is part of the volcanic segment of the Andes in Argentina, and it is considered to be part of the Central Volcanic Zone, one of the volcanic zones of the Andes. Antofalla forms a group of volcanoes that are aligned on and behind the main volcanic arc. Antofalla itself is a remote volcano.
Salar del Hombre Muerto is a salt pan in Argentina, in the Antofagasta de la Sierra Department on the border between the Salta and Catamarca Provinces. It covers an area of 600 square kilometres (230 sq mi) and is in part covered by debris. During the Pleistocene it was sometimes a lake, but today only parts of the salt pan are covered by perennial water bodies; its major tributary is the Rio de Los Patos.
Tocorpuri is a volcano in Chile, close to the border with Bolivia. Its peak height is most recently given as 5,808 metres (19,055 ft) and it features a 1.3 kilometres (0.81 mi) wide summit crater. The volcano consists mainly of lava flows and pyroclastic deposits and is subdivided into two separate edifices. Just west of Tocorpuri, the La Torta lava dome is a 200 metres (660 ft) high flat-topped structure. The volcanoes are formed by andesitic, dacitic and rhyolitic rocks.
Carachipampa is a Pleistocene volcanic cone in Argentina. Part of a wider, regional volcanic field, it has produced lava flows consisting of andesite. It is surrounded by a lake and a salt flat, the former of which features an ecosystem formed by microbes.
