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The Andean Volcanic Belt is a major
volcanic belt A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields. Volcanic belts are found above zones of unusually high temperature () where magma is created by partial melting ...
along the Andean cordillera in
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
,
Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...
,
Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
,
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
,
Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ''Eku ...
, and
Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...
. It is formed as a result of
subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...
of the Nazca Plate and
Antarctic Plate The Antarctic Plate is a tectonic plate containing the continent of Antarctica, the Kerguelen Plateau, and some remote islands in the Southern Ocean and other surrounding oceans. After breakup from Gondwana (the southern part of the superconti ...
underneath the South American Plate. The belt is subdivided into four main volcanic zones which are separated by
volcanic gap A magmatic lull is a period of declined magmatic activity in volcanically active regions. They may occur as a result of underthrusting of hinterland lithosphere beneath a volcanic arc, changes in subduction parameters such as relative velocity, di ...
s. The volcanoes of the belt are diverse in terms of activity style, products, and morphology. While some differences can be explained by which volcanic zone a volcano belongs to, there are significant differences within volcanic zones and even between neighboring volcanoes. Despite being a type location for
calc-alkalic The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic mag ...
and subduction volcanism, the Andean Volcanic Belt has a broad range of volcano-tectonic settings, as it has rift systems and extensional zones, transpressional faults, subduction of
mid-ocean ridge A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a diverge ...
s and
seamount A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abru ...
chains as well as a large range of crustal thicknesses and
magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...
ascent paths and different amounts of crustal assimilations.
Romeral Romeral is a Chilean town and commune in Curicó Province, Maule Region. The commune spans and area of . Demographics According to the 2002 census of Population and Housing by the National Statistics Institute, the Romeral commune had 12,707 in ...
in
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
is the northernmost active member of the Andean Volcanic Belt.
Global Volcanism Program The Smithsonian Institution's Global Volcanism Program (GVP) documents Earth's volcanoes and their eruptive history over the past 10,000 years. The mission of the GVP is to document, understand, and disseminate information about global volcanic a ...
South of latitude 49° S within the Austral Volcanic Zone volcanic activity decreases with the southernmost volcano
Fueguino Fueguino is a volcanic field in Chile. The southernmost volcano in the Andes, it lies on Tierra del Fuego's Cook Island and also extends over nearby Londonderry Island. The field is formed by lava domes, pyroclastic cones, and a crater lake. ...
in
Tierra del Fuego Tierra del Fuego (, ; Spanish for "Land of the Fire", rarely also Fireland in English) is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of the main island, Isla G ...
archipelago.


Volcanic zones

The Andean Volcanic Belt is segmented into four main areas of active volcanism; the Northern, Central, Southern, and Austral volcanic zones, each of which is a separate continental
volcanic arc A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc lo ...
.


Northern Volcanic Zone

The Northern Volcanic Zone (NVZ) extends from
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
to
Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ''Eku ...
and includes all volcanoes on the continental mainland of these countries. Of the volcanoes in this zone, 55 are located in Ecuador, while 19 are in Colombia. In Ecuador, the volcanoes are located in the Cordillera Occidental and the Cordillera Real while in Colombia they are located in the
Western Western may refer to: Places *Western, Nebraska, a village in the US *Western, New York, a town in the US *Western Creek, Tasmania, a locality in Australia *Western Junction, Tasmania, a locality in Australia *Western world, countries that id ...
and
Central Ranges Central Ranges (code CER) is an Australian bioregion, with an area of 101,640.44 square kilometres (39,244 sq mi) spreading across two states and one territory: South Australia, Western Australia, and the Northern Territory.Iza-Paipa volcanic complex The Paipa–Iza volcanic complex is a volcanic field of Late Pliocene to Early Pleistocene age on the Altiplano Cundiboyacense in the Eastern Ranges of the Colombian Andes. It is the northernmost volcanic complex of the Andean Volcanic Belt with ...
in Boyacá, in the
Eastern Ranges The Eastern Ranges is an Australian rules football team in the NAB League, the Victorian statewide under-18s competition. The club is a founding member of the competition (1992) and has produced several players for the Australian Football Leag ...
is the northernmost manifestation of the Northern Andean Volcanic Belt. The volcanic arc has formed due to
subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...
of the Nazca Plate underneath western South America. Some volcanoes of the Northern Volcanic Zone, such as
Galeras Galeras (Urcunina among the 16th-century indigenous people) is an Andean stratovolcano in the Colombian department of Nariño, near the departmental capital Pasto. Its summit rises above sea level. It has erupted frequently since the Spanish ...
and
Nevado del Ruiz The Nevado del Ruiz (), also known as La Mesa de Herveo ( en, Mesa of Herveo, the name of the nearby town) is a volcano on the border of the departments of Caldas and Tolima in Colombia, about west of the capital city Bogotá. It is a strat ...
that lie in densely populated highland areas, are significant sources of hazards. It has been estimated that crustal thickness beneath this region varies from around 40 to perhaps more than .
Sangay Sangay (also known as Macas, Sanagay, or Sangai) is an active stratovolcano in central Ecuador. It exhibits mostly strombolian activity. Geologically, Sangay marks the southern boundary of the Northern Volcanic Zone, and its position straddlin ...
is the southernmost volcano of the Northern Volcanic Zone. The
Geophysics Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' som ...
Institute at the National Polytechnic School in
Quito Quito (; qu, Kitu), formally San Francisco de Quito, is the capital and largest city of Ecuador, with an estimated population of 2.8 million in its urban area. It is also the capital of the province of Pichincha. Quito is located in a valley o ...
, Ecuador houses an international team of
seismologists Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...
and
volcanologist A volcanologist, or volcano scientist, is a geologist who focuses on understanding the formation and eruptive activity of volcanoes. Volcanologists frequently visit volcanoes, sometimes active ones, to observe and monitor volcanic eruptions, col ...
s whose responsibility is to monitor
Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ''Eku ...
's numerous active
volcanoes A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...
in the Andean Volcanic Belt (which is part of the
Ring of Fire The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. The Ring o ...
) and the
Galápagos Islands The Galápagos Islands (Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuador ...
.


Central Volcanic Zone

The Central Volcanic Zone (CVZ) is a volcanic arc in western South America. It is one of the four volcanic zones of the Andes. The Central Volcanic Zone extends from
Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...
to
Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
and forms the western boundary of the
Altiplano The Altiplano (Spanish for "high plain"), Collao (Quechua and Aymara: Qullaw, meaning "place of the Qulla") or Andean Plateau, in west-central South America, is the most extensive high plateau on Earth outside Tibet. The plateau is located at the ...
plateau. The volcanic arc has formed due to subduction of the Nazca Plate under western South America along the
Peru–Chile Trench The Peru–Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about off the coast of Peru and Chile. It reaches a maximum depth of below sea level in Richards Deep () and is approximately long; ...
. To the south, the CVZ is limited by the ''Pampean flat-slab segment'' or ''Norte Chico flat-slab segment'', a region devoid of volcanism due to a lower subduction angle caused by the subduction of
Juan Fernández Ridge The Juan Fernández Ridge is a volcanic island and seamount chain on the Nazca Plate. It runs in a west–east direction from the Juan Fernández hotspot to the Peru–Chile Trench at a latitude of 33° S near Valparaíso. The Juan Fernánde ...
. The CVZ is characterized by a
continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called ''sial'' be ...
that reaches a thickness of approximately . Within this zone, there are 44 major and 18 minor volcanic centers that are considered to be active. This volcanic zone also contains not less than six potentially active large
silicic Silicic is an adjective to describe magma or igneous rock rich in silica. The amount of silica that constitutes a silicic rock is usually defined as at least 63 percent. Granite and rhyolite are the most common silicic rocks. Silicic is the grou ...
volcanic systems, which include those of the Altiplano-Puna Volcanic Complex, as are
Cerro Panizos Panizos is a Late Miocene caldera in the Potosí Department of Bolivia and the Jujuy Province of Argentina. It is part of the Altiplano-Puna volcanic complex of the Central Volcanic Zone in the Andes. 50 volcanoes active in recent times are found ...
,
Pastos Grandes Pastos Grandes is the name of a caldera and its crater lake in Bolivia. The caldera is part of the Altiplano-Puna volcanic complex, a large ignimbrite province that is part of the Central Volcanic Zone of the Andes. Pastos Grandes has erupted a ...
, Cerro Guacha, and
La Pacana 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 f ...
. Other silicic systems are
Los Frailes ignimbrite plateau Los Frailes is an ignimbrite plateau in Bolivia, between the city of Potosi and the Lake Poopo. It belongs to a group of ignimbrites that exist in the Central Andes and which includes the Altiplano–Puna volcanic complex. The plateau covers a s ...
in
Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...
, and the
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
complexes of Incapillo and Cerro Galán in
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
.


Southern Volcanic Zone

The South Volcanic Zone (SVZ) extends roughly from Central Chile's Andes at the latitude of
Santiago Santiago (, ; ), also known as Santiago de Chile, is the capital and largest city of Chile as well as one of the largest cities in the Americas. It is the center of Chile's most densely populated region, the Santiago Metropolitan Region, whose ...
, at ca. 33°S, to
Cerro Arenales Cerro Arenales is a heavily ice-covered stratovolcano located in the Aysén del General Carlos Ibáñez del Campo Region of Chile, within Laguna San Rafael National Park. It towers over the southern part of the Northern Patagonian Ice Field. ...
in
Aysén Region The Aysén del General Carlos Ibáñez del Campo Region ( es, Región de Aysén, , '), often shortened to Aysén Region or Aisén,Examples of name usage1, official regional government site refers to the region as "Región de Aysén"., Chile's of ...
at ca. 46°S, a distance of well over . The arc has formed due to subduction of the Nazca Plate under the South American Plate along the
Peru–Chile Trench The Peru–Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about off the coast of Peru and Chile. It reaches a maximum depth of below sea level in Richards Deep () and is approximately long; ...
. The northern boundary of the SVZ is marked by the
flat-slab subduction Flat slab subduction is characterized by a low subduction angle (<30 degrees to horizontal) beyond the seismogenic layer and a resumption of normal ...
of the
Juan Fernández Ridge The Juan Fernández Ridge is a volcanic island and seamount chain on the Nazca Plate. It runs in a west–east direction from the Juan Fernández hotspot to the Peru–Chile Trench at a latitude of 33° S near Valparaíso. The Juan Fernánde ...
, which is believed to have produced a volcanic gap called the
Pampean flat-slab segment The Pampean flat-slab is the low angle subduction of oceanic lithosphere beneath Northern Argentina. The Pampean flat-slab is one of three flat slabs in South America, the other being the Peruvian flat-slab and the Bucaramanga flat-slab. It is ...
in the Norte Chico region since the late
Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
. The southern end of the SVZ is marked by the Chile Triple Junction where the
Chile Rise The Chile Ridge, also known as the Chile Rise, is a submarine oceanic ridge formed by the divergent plate boundary between the Nazca Plate and the Antarctic Plate. It extends from the triple junction of the Nazca, Pacific, and Antarctic plates t ...
subducts under South America at the
Taitao Peninsula The Taitao Peninsula (Spanish: ''Península de Taitao'') is a westward projection of the mainland of Chile, with which it is connected by the narrow Isthmus of Ofqui, over which the natives and early missionaries were accustomed to carry their boa ...
giving origin to the ''Patagonian Volcanic Gap''. Further south lies the Austral Volcanic Zone. From north to south the Southern Volcanic Zone is divided into four segments according to the characteristics of the
continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called ''sial'' be ...
, volcanoes and
volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic r ...
s: *Northern SVZ (NSVZ; 33°S–34°30′S) *Transitional SVZ (TSVZ; 34°30′S–37°S) *Central SVZ (CSVZ; 37°S–41.5°S) *Southern SVZ (SSVZ: 41.5°S–46°S) In Central Southern Volcanic Zone and Southern Southern Volcanic Zone, magma ascent occur primarily by the
Liquiñe-Ofqui Fault The Liquiñe-Ofqui Fault is major geological fault that runs a length of roughly in a NNE-SSW orientation and exhibits current seismicity. It is located in the Chilean Northern Patagonian Andes. It is a dextral intra-arc strike-slip fault. Most ...
. The
Principal Cordillera Principal Cordillera ( es, Cordillera Principal) is the Andean mountain range that makes up the boundary between Central Chile and neighbouring areas of Argentina. It is also a continental divide between the Atlantic and the Pacific watersheds. ...
of Andes (east Santiago) rose in late Cenozoic and became extensively glaciated about one million years ago. This meant lavas from NSVZ volcanoes begun to be channeled along a network of glacial valleys ever since. The Maipo caldera exploded about 450 thousand years ago, leaving behind copious amounts of ash and ignimbrite rock that can be observed today both in Chile and Argentina. During the
Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Nazca Nazca (; sometimes spelled Nasca; qu, Naska) is a city and system of valleys on the southern coast of Peru. It is also the name of the largest existing town in the Nazca Province. The name is derived from the Nazca culture, which flourished in ...
and the South American Plate from per year to per year 2–3 million years ago contributed to a narrowing of the southern SVZ that occurred possibly 1.6 million years ago. The southern part of the SVZ retained vigorous activity only in the west, especially around the Liquiñe-Ofqui Fault Zone, while eastern volcanoes such as
Tronador Tronador ( es, Cerro Tronador) is an extinct stratovolcano in the southern Andes, located along the border between Argentina and Chile, near the Argentine city of Bariloche. The mountain was named ''Tronador'' (Spanish for "Thunderer") by locals ...
and
Cerro Pantoja Cerro Pantojo is an extinct basaltic stratovolcano on the border of Argentina and Chile. It lies immediately south of Cardenal Antonio Samoré Pass and its characteristic spire-shaped summit is an eroded volcanic plug. It also has flank lava fl ...
became extinct. The magmas of modern (
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
) volcanoes in the Transitional Southern Volcanic Zone are derived from heterogenous sources in the
Earth's mantle Earth's mantle is a layer of silicate rock between the crust and the outer core. It has a mass of 4.01 × 1024 kg and thus makes up 67% of the mass of Earth. It has a thickness of making up about 84% of Earth's volume. It is predominantly sol ...
. Many lesser parts of melts are derived from subducted
oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumu ...
and subducted sediments. Towards the east, in the
backarc The back-arc region is the area behind a volcanic arc. In island volcanic arcs, it consists of back-arc basins of oceanic crust with abyssal depths, which may be separated by remnant arcs, similar to island arcs. In continental arcs, the back- ...
region, the degree of melting in the mantle that gave origin to volcanism is less as are the subducted crust influences. Several volcanoes of the SVZ are being monitored by the
Southern Andean Volcano Observatory The Southern Andean Volcano Observatory (Spanish: ''Observatorio Volcanológico de los Andes del Sur''), also known by its acronyms as OVDAS, is part of ''Red Nacional de Vigilancia Volcánica'', a program of the Chilean National Geology and Minin ...
(OVDAS) based in
Temuco Temuco () is a city and commune, capital of the Cautín Province and of the Araucanía Region in southern Chile. The city is located south of Santiago. The city grew out from a fort of the same name established in 1881 during Chile's invasion ...
. The volcanoes monitored have varied over time but some like Villarrica and
Llaima The Llaima Volcano is one of the largest and most active volcanoes in Chile. It is situated 82 km East of Temuco and 663 km South of Santiago, within the borders of Conguillío National Park. Geography The top of Llaima consists of tw ...
are monitored constantly. In recent years, there have been major eruptions at
Chaitén Chaitén (, ) is a Chilean town, commune and former capital of the Palena Province in Los Lagos Region. The town is north of the mouth of Yelcho River, on the east coast of the Gulf of Corcovado. The town is strategically close to the northern ...
(2008–2010),
Cordón Caulle Cordón is a central ''barrio'' (neighbourhood or district) of Montevideo, Uruguay, located East of the Centro. Its main avenue is 18 de Julio Avenue. History Cordón was the first neighborhood to be created outside the walls of the old Citade ...
(2011) and
Calbuco Calbuco is a city and commune in southern Chile administered by the Municipality of Calbuco. Administratively Calbuco belongs to the Llanquihue Province of Los Lagos Region. The origin of the city was the Spanish Fort Calbuco founded in 1603, an ...
(2015).


Austral Volcanic Zone

The Austral Volcanic Zone (AVZ) is a
volcanic arc A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc lo ...
in the Andes of southwestern South America. It is one of the four volcanic zones of the Andes. The AVZ extends south of the Patagonian Volcanic Gap to
Tierra del Fuego Tierra del Fuego (, ; Spanish for "Land of the Fire", rarely also Fireland in English) is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of the main island, Isla G ...
archipelago, a distance of well over 600 mi (1,000 km). The arc has formed due to subduction of the
Antarctic Plate The Antarctic Plate is a tectonic plate containing the continent of Antarctica, the Kerguelen Plateau, and some remote islands in the Southern Ocean and other surrounding oceans. After breakup from Gondwana (the southern part of the superconti ...
under the South American Plate. Eruption products consist chiefly of alkaline
basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
and
basanite Basanite () is an igneous, volcanic (extrusive) rock with aphanitic to porphyritic texture. It is composed mostly of feldspathoids, pyroxenes, olivine, and plagioclase and forms from magma low in silica and enriched in alkali metal oxides that s ...
. Volcanism in the Austral Volcanic Zone is less vigorous than in the Southern Volcanic Zone. Recorded eruptions are rare due to the area being unexplored well into the 19th century; the cloudy weather of its western coast might also have prevented sightings of eruptions. The Austral Volcanic Zone hosts both glaciated stratovolcanoes as well as subglacial volcanoes under the
Southern Patagonian Ice Field The Southern Patagonian Ice Field ( es, Hielo Continental or '), located at the Southern Patagonic Andes between Chile and Argentina, is the world's second largest contiguous extrapolar ice field. It is the bigger of two remnant parts of the P ...
.


Volcanic gaps

The different volcanic zones are intercalated by volcanic gaps, zones that, despite lying at the right distance from an oceanic trench, lack volcanic activity. The Andes has three major volcanic gaps the ''Peruvian flat-slab segment'' (3 °S–15 °S), the ''Pampean flat-slab segment'' (27 °S–33 °S) and the ''Patagonian Volcanic Gap'' (46 °S–49 °S). The first one separates the Northern from the Central Volcanic Zone, the second the Central from the Southern and the last separates the Southern from the Austral Volcanic Zone. The Peruvian and Pampean gaps coincide with areas of flat slab (low angle) subduction and therefore the lack of volcanism is believed to be caused by the shallow dip of the subducting Nazca Plate in these places. The shallow dip has in turn been explained by the subduction of the
Nazca Ridge The Nazca Ridge is a submarine ridge, located on the Nazca Plate off the west coast of South America. This plate and ridge are currently subducting under the South American Plate at a convergent boundary known as the Peru-Chile Trench at approx ...
and the
Juan Fernández Ridge The Juan Fernández Ridge is a volcanic island and seamount chain on the Nazca Plate. It runs in a west–east direction from the Juan Fernández hotspot to the Peru–Chile Trench at a latitude of 33° S near Valparaíso. The Juan Fernánde ...
for the Peruvian and Pampean gaps respectively. Since the Nazca and Juan Fernández Ridge are created by volcanic activity in Pacific hotspots (
Easter Easter,Traditional names for the feast in English are "Easter Day", as in the '' Book of Common Prayer''; "Easter Sunday", used by James Ussher''The Whole Works of the Most Rev. James Ussher, Volume 4'') and Samuel Pepys''The Diary of Samuel ...
and Juan Fernández) it can be said that volcanic activity in the Pacific is responsible for the suppression of volcanism in parts of the Andes. The Patagonian gap is different in nature as it is caused not by the subduction of an aseismic ridge but by the subduction of the
Chile Rise The Chile Ridge, also known as the Chile Rise, is a submarine oceanic ridge formed by the divergent plate boundary between the Nazca Plate and the Antarctic Plate. It extends from the triple junction of the Nazca, Pacific, and Antarctic plates t ...
, the boundary ridge between the Nazca and the Antarctic Plate.


Peruvian gap

Between the latitudes of 3 °S–15 °S in Peru the last volcanic activity occurred 2.7 million years ago in
Cordillera Blanca The Cordillera Blanca (Spanish for "white range") is a mountain range in Peru that is part of the larger Andes range and extends for between 8°08' and 9°58'S and 77°00' and 77°52'W, in a northwesterly direction. It includes several peaks ove ...
. The lack of volcanism in central and northern Peru is widely attributed to a side effect of the flat-slab (low angle)
subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...
of the Nazca Plate occurring there. While the subduction of the
Nazca Ridge The Nazca Ridge is a submarine ridge, located on the Nazca Plate off the west coast of South America. This plate and ridge are currently subducting under the South American Plate at a convergent boundary known as the Peru-Chile Trench at approx ...
has often been credited for causing this flat-slab and hence the lack of volcanism, many researchers find the gap too wide to be explained by this alone. One hypothesis claims that the flat-slab is caused by the ongoing subduction of an
oceanic plateau An oceanic or submarine plateau is a large, relatively flat elevation that is higher than the surrounding relief with one or more relatively steep sides. There are 184 oceanic plateaus in the world, covering an area of or about 5.11% of the ...
. This hypothetical plateau named ''Inca Plateau'' would be a mirror image of the Marquesas Plateau in the South Pacific.


Pampean gap

The Pampean gap or Norte Chico separates the Andes Central and Southern volcanic zones. A low
subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...
angle caused by the subduction of
Juan Fernández Ridge The Juan Fernández Ridge is a volcanic island and seamount chain on the Nazca Plate. It runs in a west–east direction from the Juan Fernández hotspot to the Peru–Chile Trench at a latitude of 33° S near Valparaíso. The Juan Fernánde ...
has been pointed out as causing or contributing to the suppression of volcanism.


Back-arc volcanism

Back-arc A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most o ...
volcanism is a significant phenomenon in Argentine
Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...
and
Mendoza Province Mendoza, officially Province of Mendoza, is a province of Argentina, in the western central part of the country in the Cuyo region. It borders San Juan to the north, La Pampa and Neuquén to the south, San Luis to the east, and the republic o ...
. Flat-slab
subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...
along the
Peru–Chile Trench The Peru–Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about off the coast of Peru and Chile. It reaches a maximum depth of below sea level in Richards Deep () and is approximately long; ...
during the
Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
has been pointed out as being responsible for back-arc volcanism in Mendoza and
Neuquén Province Neuquén () is a province of Argentina, located in the west of the country, at the northern end of Patagonia. It borders Mendoza Province to the north, Rio Negro Province to the southeast, and Chile to the west. It also meets La Pampa Province a ...
during the
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
. Notable back-arc volcanoes include
Payun Matru The Reserva Provincial La Payunia ( es, La Payunia Provincial Reserve) also known as Payún or Payén is a natural reserve located in the Malargüe Department in the southern part of Mendoza Province, Argentina, about 160 km away from Malar ...
,
Agua Poca Agua Poca is a monogenetic volcano in the Puelén Department of Argentina. The volcano has the form of a cinder cone and has been active in the Pleistocene. Accessibility The volcano is situated southwest of Puelén and it can be reached from ...
,
Payun Liso The Reserva Provincial La Payunia ( es, La Payunia Provincial Reserve) also known as Payún or Payén is a natural reserve located in the Malargüe Department in the southern part of Mendoza Province, Argentina, about 160 km away from Mala ...
,
Pali-Aike Volcanic Field The Pali-Aike volcanic field is a volcanic field along the Argentina–Chile border. It is part of a family of back-arc volcanoes in Patagonia, which formed from processes involving the collision of the Chile Ridge with the Peru–Chile Trench. ...
,
Tromen Tromen is a stratovolcano in western Argentina. It rises above the older caldera of the Volcán Negro del Tromen. See also * List of volcanoes in Argentina This is a list of active and extinct volcanoes in Argentina. Volcanoes {, cla ...
,
Cochiquito Volcanic Group The Cochiquito Volcanic Group is a small volcanic group of volcanoes north of the town of Buta Ranquil in Argentina. The main peak is Volcán Cochiquito, a stratovolcano of estimated Pleistocene–Holocene age. There are eight satellite cones in ...
and Puesto Cortaderas. Other significant back-arc volcanism regions include the
Argentine Northwest The Argentine Northwest (''Noroeste Argentino'') is a geographic and historical region of Argentina composed of the provinces of Catamarca, Jujuy, La Rioja, Salta, Santiago del Estero and Tucumán. Geography The Argentine Northwest comprises v ...
where the Galán Caldera is located and the Andean foothills of Ecuador's Cordillera Real, where a series of alkaline volcanoes like Sumaco develops.


Geothermal activity

The Andean Volcanic Belt represents a large geothermal province, with numerous
hot springs A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by circ ...
,
solfatara A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...
s and
geyser A geyser (, ) is a spring characterized by an intermittent discharge of water ejected turbulently and accompanied by steam. As a fairly rare phenomenon, the formation of geysers is due to particular hydrogeological conditions that exist only in ...
s associated with its volcanoes. Already in the pre-Columbian era, the indigenous peoples used the various hot springs as places of healing. The
geothermal exploration Geothermal exploration is the exploration of the subsurface in search of viable active geothermal regions with the goal of building a geothermal power plant, where hot fluids drive turbines to create electricity. Exploration methods include a bro ...
in the Chilean Andes was pioneered in the 1960s, although the site of El Tatio was investigated previously in the 1920s. Compared to neighboring
Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
, the Andean region is poorly explored and exploited for geothermal resources.


See also

*
List of volcanoes in Argentina This is a list of active and extinct volcanoes in Argentina. Volcanoes {, class="wikitable sortable" style="text-align:right;" , - style="text-align:center;" ! rowspan="2" , Name ! rowspan="2" , Type ! colspan="2" , Elevation ! Location ...
*
List of volcanoes in Bolivia The country of Bolivia hosts numerous activeIn vulcanology and this article active volcanoes are those with Holocene eruption, that means eruptions in the last 10,000 years. and extinct volcanoes across its territory. The active volcanoes are i ...
*
List of volcanoes in Chile The Smithsonian Institution's Global Volcanism Program lists 105 volcanoes in Chile that have been active during the Holocene.List of volcanoes in Peru This is a list of active and extinct volcanoes in Peru. Notes References *John , Volcano LiveVolcanoes of Peru
Retrieved December 27, 2007 *Peakware World Mountain Encyclopedia, , Retrieved December 27, 2007 {{Andean volca ...


References


External links


B and 11B behaviour in the Northern Volcanic Zone of the Andes. Insights on the devolatilization of the slab and related magma genesis processes.OVDAS website
{{Andean volcanoes Volcanic belts Volcanoes of Peru Volcanoes of Ecuador Volcanoes of Argentina Volcanoes of Colombia Volcanoes of Bolivia Volcanoes of South America