Puyehue (; ) and Cordón Caulle are two coalesced

volcanic A volcano is commonly defined as a vent or fissure 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 fo ...

edifices that form a major mountain

massif A massif () is a principal mountain mass, such as a compact portion of a mountain range, containing one or more summits (e.g. France's Massif Central). In mountaineering literature, ''massif'' is frequently used to denote the main mass of an ...

in Puyehue National Park in the

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

of Ranco Province, in the South of Chile. In

volcanology Volcanology (also spelled vulcanology) is the study of volcanoes, lava, magma and related geology, geological, geophysical and geochemistry, geochemical phenomena (volcanism). The term ''volcanology'' is derived from the Latin language, Latin ...

this group is known as the Puyehue-Cordón Caulle Volcanic Complex (PCCVC). Four volcanoes constitute the volcanic group or complex, the Cordillera Nevada

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

, the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58fissure vent A fissure vent, also known as a volcanic fissure, eruption fissure or simply a fissure, is a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is often a few metres wide and may be many kilo ...

s and the Puyehue

stratovolcano A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with ...

. Like most stratovolcanoes in the Southern Volcanic Zone of the

Andean Volcanic Belt The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. It is formed as a result of subduction of the Nazca plate and Antarctic plate underneath the South Americ ...

, Puyehue and Cordón Caulle are along the intersection of a traverse

fracture Fracture is the appearance of a crack or complete separation of an object or material into two or more pieces under the action of stress (mechanics), stress. The fracture of a solid usually occurs due to the development of certain displacemen ...

with the larger north–south Liquiñe-Ofqui Fault. The volcanic complex has shaped the local landscape and produced a huge variety of volcanic landforms and products over the last 300,000 years.

Cinder cone A cinder cone or scoria cone is a steep, volcanic cone, conical landform of loose pyroclastic rock, pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are forme ...

lava dome In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...

s and craters can be found in the area apart from the widest variety of

volcanic rock Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and me ...

s in all the Southern Zone, for example both primitive

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 ...

s and

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matri ...

s. Cordón Caulle erupted shortly after the Great Chilean Earthquake. With a magnitude of 9.5, it remains the largest recorded earthquake in history. Apart from this, the Puyehue-Cordón Caulle area is one of the main sites of exploration for

geothermal power Geothermal power is electricity generation, electrical power generated from geothermal energy. Technologies in use include dry steam power stations, flash steam power stations and binary cycle power stations. Geothermal electricity generation i ...

in Chile.

Geothermal activity Geothermal activity is a group of natural heat transfer processes, occurring on Earth's surface, caused by the presence of excess heat in the subsurface of the affected area, usually caused by the presence of an igneous intrusion underground. Geot ...

is manifested on the surface of Puyehue and Cordón Caulle as several boiling springs and

fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or another 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. Most of the stone artifacts found in Pilauco Bajo (dated to c. 12.5 to 13.5 ka BP) are made of

dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...

rhyodacite Rhyodacite is a volcanic rock intermediate in composition between dacite and rhyolite. It is the extrusive equivalent of those plutonic rocks that are intermediate in composition between monzogranite and granodiorite. Rhyodacites form from rapid ...

and

from the Puyehue-Cordón Caulle. Yet these rocks were imported by humans to the site as nearby rivers have not transported them.

Approach and ascent

From the south, the Cordón Caulle can be approached from Fundo El Caulle on Route 215-CH, which goes from Osorno to Bariloche in Argentina through Samoré Pass. Some 1,000 m up on forested slope there is a campsite and

mountain shelter A mountain hut is a building located at high elevation, in mountainous terrain, generally accessible only by foot, intended to provide food and shelter to mountaineering, mountaineers, climbing, climbers and Hiking, hikers. Mountain huts are us ...

. According to the homepage of Puyehue National Park the shelter can be reached after four hours walking. The access through El Caulle is not public as it is not inside Puyehue National Park; and an entrance fee of 10,000 CLP, as of 2009, has to be paid, of which 3,000 are refunded if visitor packs out his garbage. From the north, there are tracks from the vicinities of Nilahue Valley near Ranco Lake. The track ascends ca 1,000 m through dense forest to the Cordón Caulle area. From the relatively flat Cordón Caulle there is further ca 600 m of ascent over

tephra Tephra is fragmental material produced by a Volcano, volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, ...

and loose rocks to the summit of Puyehue. In the Nilahue area there are arrieros who offer horseback trips to Cordón Caulle.

Geography

Puyehue, Cordón del Caulle, and Cordillera Nevada form a northwest trending

in the Ranco Province of the Andes. The three volcanoes are coalesced. Puyehue is located in the southeast, Cordón Caulle in the center, and Cordillera Nevada, which owes its name to its often snowy appearance from the relatively densely populated

Chilean Central Valley The Central Valley (), Intermediate Depression, or Longitudinal Valley is the depression between the Chilean Coastal Range and the Andes Mountains. The Chilean Central Valley extends from the border with Peru to Puerto Montt in southern Chile, wi ...

, is at the northwestern end. The massif is located between two lakes, Ranco Lake in the north and

Puyehue Lake Puyehue Lake (), (Mapudungun: ''puye'', "small fish" and ''hue'', "place") is an Andean piedmont lake on the border of Los Lagos Region with Los Ríos Region of Chile. Puyehue is a lake of glacial origin. Several times during the Pleistocene gl ...

in the south. The fact that Puyehue volcano is named after Puyehue Lake reflects that it is better seen and more accessible from the south. Cordillera Nevada is a wide semicircular

and corresponds to the remnants of a collapsed volcano. Cordillera Nevada covers an area of . Cordón Caulle is a northwest trending ridge that hosts a volcanic-

tectonic Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...

graben In geology, a graben () is a depression (geology), depressed block of the Crust (geology), crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German language, German, meaning 'ditch' or 't ...

in which a

fissure vent A fissure vent, also known as a volcanic fissure, eruption fissure or simply a fissure, is a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is often a few metres wide and may be many kilo ...

is developed. Puyehue Volcano is a

located on the southeastern end of Cordón Caulle, just east of the main fault of the Liquiñe-Ofqui Fault Zone. Its cone hosts a wide crater, and products of Puyehue volcanism cover an approximate area of .

Flora

The lower parts of the mountains are covered by an alpine plant association of

Valdivian temperate rainforest The Valdivian temperate forests (NT0404) is an ecoregion on the west coast of southern South America, in Chile and Argentina. It is part of the Neotropical realm. The forests are named after the city of Valdivia. The Valdivian temperate rainfores ...

, where plant species such as '' Chusquea coleou'' and ''

Nothofagus dombeyi ''Nothofagus dombeyi'', Dombey's beech, coigue, coihue or coigüe (from Mapudungun ''koywe'') is a tree species native to southern Chile and the Andean parts of Argentine Patagonia. It is a fast-growing species that can live in a wide range o ...

'' are common. The

tree line The tree line is the edge of a habitat at which trees are capable of growing and beyond which they are not. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions (usually low ...

, lying around elevation, is mostly made up of ''

Nothofagus pumilio ''Nothofagus pumilio'', the lenga beech (from the Mapuche language), is a deciduous tree or shrub in the Nothofagaceae family that is native to the southern Andes range, in the temperate forests of Chile and Argentina to Tierra del Fuego, from 35 ...

''. Above this line lies a volcanic desert and

alpine tundra Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation, with an associated harsh climate. As the latitude of a location approaches the poles, the threshold elevation for alpine tundra gets ...

s. The main plant species present in these high elevations are ''

Gaultheria mucronata ''Gaultheria mucronata'' ( syn. ''Pernettya mucronata''; also known as prickly heath, chaura, or murtillo) is a species of flowering plant in the family Ericaceae, native to southern Argentina and Chile. In volcanic areas of southern Chile ''G ...

'', '' Empetrum rubrum'', '' Hordeum comosum'' and '' Cissus striata''.

Geologic history

The volcanic complex that comprises Puyehue, Cordón Caulle and Cordillera Nevada has a long record of active history spanning from 300,000 years ago to the present. The older parts of the Cordillera Nevada caldera and Mencheca volcano reflect even older activity from the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

.Lara, L., Rodríguez C., Moreno, H. and Pérez de Arce, C. Geocronología K-Ar y geoquímica del volcanismo plioceno superior-pleistoceno de los Andes del sur (29–42°S). Revista Geológica de Chile, July 2001. In the past 300,000 years, there have been a series of changes in magmatic composition, locus of volcanic activity, magma output rates and eruptive styles.

Ancestral volcanoes

Some 300,000 years ago, important changes occurred in the area of Puyehue. The old Pliocene volcano Mencheca, currently exposed just northeast of Puyehue's cone, declined in activity. This decline was probably due a regional change in the location of the active front of the Southern Volcanic Zone that also affected other volcanoes such as Tronador and Lanín. The relocation of the active front gave rise to new volcanoes further westward or increased their activity. The formerly broad magmatic belt narrowed, retaining vigorous activity only in its westernmost parts. Associated with these changes are the oldest rocks of PCCVC, those that belong to Sierra Nevada. Sierra Nevada grew over time to form a large

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...

, during the same time Cordón Caulle was also being built up having rather silicic products compared to coeval Sierra Nevada and Mencheca. The oldest rocks from proper Puyehue volcano are 200,000 years old, representing the youngest possible age for this volcano. It is estimated that some 100,000 years ago in the period between Río Llico and Llanquihue glaciation a large

ignimbrite Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...

called San Pablo was produced. This ignimbrite covers an estimated area of immediately west of Cordillera Nevada, stretching across the

almost reaching the

Chilean Coast Range The Chilean Coastal Range () is a mountain range that runs from north to south along the Pacific Ocean, Pacific coast of South America parallel to the Andes, Andean Mountains, extending from Morro de Arica in the north to Taitao Peninsula, where ...

. The San Pablo ignimbrite has been associated with the formation of the Cordillera Nevada Caldera.

Volcanism during the Llanquihue glaciation

During the Llanquihue glaciation volcanism occurred on all three vents, Cordillera Nevada, Cordón Caulle and Puyehue volcano. During most of this time the volcano was covered by the

Patagonian Ice Sheet The Patagonian Ice Sheet was a large elongated and narrow ice sheet centered in the southern Andes that existed during the Llanquihue glaciation. The ice sheet covered all of Chile south of Puerto Montt plus the western fringes of Argentine Pa ...

, leaving glacial striae on many lava outcrops and affecting the volcanic activity. In Cordillera Nevada this volcanism was expressed from about 117,000 years ago primarily as dacitic lava flows erupted along ring faults. These lava flows partly filled the caldera and flowed north, out to what is now Nilahue River. In mid or late glacial times cordillera Nevada produced its last lavas which were andesitic to dacitic in composition. Cordón Caulle evolved during this time from being a shield volcano to a

with

s. This was accompanied by emission of ignimbrites and dacitic lava flows. Puyehue was characterized by eruption of basaltic andesites to dacites until its activity turned bimodal at around 34,000 years ago. The onset of this change was marked by the eruption of

mingled with basaltic andesite rich in

magnesium oxide Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...

(MgO). The bimodal activity continued with a small hiatus around 30,000 years ago until around 19,000 years ago when Puyehues started to produce lava domes and flows of dacitic to rhyolitic composition, a trend that lasted until 12,000 years before present. Between 15,000 and 12,000 years ago Puyehue also erupted basaltic andesite. During the Llanquihue glaciation Puyehue volcano produced some of the most primitive basalts of the Southern Volcanic Zone with a magnesium oxide mass percentage of 14.32, which is in

equilibrium Equilibrium may refer to: Film and television * ''Equilibrium'' (film), a 2002 science fiction film * '' The Story of Three Loves'', also known as ''Equilibrium'', a 1953 romantic anthology film * "Equilibrium" (''seaQuest 2032'') * ''Equilibr ...

with melt from mantle

peridotite Peridotite ( ) is a dense, coarse-grained igneous rock consisting mostly of the silicate minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium (Mg2+), reflecting the high pr ...

Postglacial volcanism

Only Puyehue and Cordón Caulle have erupted during the

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

, and until 2011 only Cordón Caulle had recorded historical eruptions. In the interval between 7,000 and 5,000 years ago Puyehue had rhyolitic eruptions that produced

s. The lava domes were later destroyed after a sequence of strong eruptions that were part of an explosive eruptive cycle. These last eruptions were likely of phreatomagmatic and sub-plinian type and occurred around 1,100 years ago (~850 CE).Singer, Brad S., Jicha, Brian R., Harper. Melissa A., Naranjo, José A., Lara, Luis E., Moreno-Roa, Hugo. ''Eruptive history, geochronology, and magmatic evolution of the Puyehue-Cordón Caulle volcanic complex'', Chile. GSA Bulletin. 2008.

Recent eruptions

Eruptive records in Cordón Caulle, the only active centre in the Puyehue-Cordón Caulle system in historical times, are relatively scarce. This is explained by the geographical position of Cordón Caulle and the history of Spanish and Chilean settlement in southern Chile. After a failed attempt in 1553, governor García Hurtado de Mendoza founded the city of Osorno in 1558, the only Spanish settlement in the zone, west of Cordón Caulle. This settlements had to be abandoned in 1602 due to conflicts with native

Huilliche The Huilliche (), Huiliche or Huilliche-Mapuche are the southern partiality of the Mapuche macroethnic group in Chile and Argentina. Located in the Zona Sur, they inhabit both Futahuillimapu ("great land of the south") and, as the Cunco or Ve ...

s. No eruption record is known from this era. From 1602 to the mid-18th century there were no Spanish settlements within a radius of . The closest were

Valdivia Valdivia (; Mapuche: Ainil) is a city and commune in southern Chile, administered by the Municipality of Valdivia. The city is named after its founder, Pedro de Valdivia, and is located at the confluence of the Calle-Calle, Valdivia, and ...

and the sporadic missions of Nahuel Huapi all of them out of sight of the volcano. In 1759 an eruption was noticed in the Cordillera, although this is mainly attributed to Mocho. By the end of the 19th century most of the Central Valley west of Cordón Caulle had been settled by Chileans and European immigrants and an eruption was reported in 1893. The next report came in 1905, but the eruption of 8 February 1914 is the first one certain to have occurred.

1921–1922, 1929 and 1934 eruptions

On 13 December 1921, Cordón Caulle began a sub-

plinian eruption Plinian eruptions or Vesuvian eruptions are volcanic eruptions characterized by their similarity to the eruption of Mount Vesuvius in 79 AD, which destroyed the ancient Roman cities of Herculaneum and Pompeii. The eruption was described in a le ...

, with a high plume, periodic explosions and

seismicity Seismicity is a measure encompassing earthquake occurrences, mechanisms, and magnitude at a given geographical location. As such, it summarizes a region's seismic activity. The term was coined by Beno Gutenberg and Charles Francis Richter in 194 ...

. The eruption had a

Volcanic Explosivity Index The volcanic explosivity index (VEI) is a scale used to measure the size of explosive volcanic eruptions. It was devised by Christopher G. Newhall of the United States Geological Survey and Stephen Self in 1982. Volume of products, eruption c ...

of 3 and ended in February 1922. In 1929 and 1934 the Cordón Caulle had fissure eruptions, both with an estimated

of 2.

1960 eruption

Two days after the main shock of the

1960 Valdivia earthquake The 1960 Valdivia earthquake and tsunami () or the Great Chilean earthquake (''Gran terremoto de Chile'') occurred on 22 May 1960. Most studies have placed it at 9.5–9.6 on the moment magnitude scale, while some studies have placed the magnitu ...

, the largest earthquake recorded in history, Cordón Caulle erupted. The eruption was believed to have been caused by the earthquake. The earthquake had struck the whole of Chile between

Talca Talca () is a city and commune in Chile located about south of Santiago, and is the capital of both Talca Province and Maule Region (7th Region of Chile). As of the 2012 census, the city had a population of 201,142. The city is an important ...

(30°S) and Chiloé (43°S) and had an estimated moment magnitude of 9.5. Being located between two sparsely populated and by then isolated Andean valleys, the eruption had few eyewitnesses and received little attention by local media due to the huge damages and losses caused by the main earthquake.Lara, L.E., Naranjo J.A., Moreno, H. "Rhyodacitic fissure eruption in Southern Andes (''Cordón Caulle''; 40.5°S) after the 1960 (Mw:9.5) Chilean earthquake: a structural interpretation". ''

Journal of Volcanology and Geothermal Research ''Journal of Volcanology and Geothermal Research'' is a scientific journal that publishes recent research on the fields of volcanology and geothermal activity, as well as the societal and environmental impact of these phenomenon. Abstracting and ...

''. vol 138. 2004. The eruption was fed by a long and north west-west (N135°) trending fissure along which 21 individual vents have been found. These vents produced an output of about 0.25 km³

DRE DRE may refer to: * ''Dre'' (album), 2010 by American rapper Soulja Boy Tell 'Em, 2010 * Dre (given name) **Dr. Dre Andre Romell Young (born February 18, 1965), known professionally as Dr. Dre, is an American rapper, record producer, recor ...

both in form of

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

s and

. The eruption began in a sub-plinian style creating a column of

volcanic gas Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (Vesicular texture, vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from ...

pyroclast Tephra is fragmental material produced by a Volcano, volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, ...

s and ash about 8 km in height. The erupting N135° trending fissure had two craters of major activity emplaced at each end; the Gris Crater and El Azufral Crater. Volcanic vents of Cordón Caulle that were not in eruption produced visible

steam Steam is water vapor, often mixed with air or an aerosol of liquid water droplets. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Saturated or superheated steam is inv ...

emissions. After this explosive phase the eruption changed character to a more effusive one marked by rhyodacitic blocky and Aa type lava flows emitted from the vents along the N135° trending fissure. A third phase followed with the appearance of short north-north west (N165°) oriented vents transverse to the main fissure which also erupted rhyodacitic lava. The third phase ended temporarily with viscous lava obstructing the vents, but continued soon with explosive activity restricted to the Gris and El Azufral craters. The eruption came to an end on 22 July.

1960–2011 period

Following the end of the 1960 eruption, Cordón Caulle has remained relatively quiet if compared with the first half of the 20th century. On 2 March 1972 there was a report of an eruption west of Bariloche in Argentina. The Chilean emergency office ONEMI (Oficina Nacional de Emergencia del Ministerio del Interior) organized a flight over the area with two

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 aboard. Puyehue and Cordón Caulle as well the Carrán crater were found without activity. From accounts of local inhabitants of the area it is inferred that a small pumice cone was formed around 1990. In 1994 a temporarily emplaced seismic network registered tremors north of Puyehue's

cone In geometry, a cone is a three-dimensional figure that tapers smoothly from a flat base (typically a circle) to a point not contained in the base, called the '' apex'' or '' vertex''. A cone is formed by a set of line segments, half-lines ...

which reached IV and V degrees on the

Mercalli intensity scale The Modified Mercalli intensity scale (MM, MMI, or MCS) measures the effects of an earthquake at a given location. This is in contrast with the seismic magnitude usually reported for an earthquake. Magnitude scales measure the inherent force or ...

. This prompted ONEMI to invoke an emergency action committee, however soon afterward unrest ceased. Between 4 and 17 May 2011

seismic activity An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

partly attributed to the movements of fluids was detected Southern Andean Volcano Observatory (OVDAS). The activity concentrated around and in Cordillera Nevada

and on western Cordón Caulle. This prompted SERNAGEOMIN-OVDAS to declare yellow alert.

2011–2012 eruption

A new eruption started on 4 June 2011. By this time, 3,500 people had been evacuated from nearby areas, while an ash cloud reaching blew toward the city of Bariloche, Argentina, where the local airport was closed. At approximately 16:30 local time, Neuquén airport further east in Argentina was also closed due to the ash cloud. Airports as far away as

Buenos Aires Buenos Aires, controlled by the government of the Autonomous City of Buenos Aires, is the Capital city, capital and largest city of Argentina. It is located on the southwest of the Río de la Plata. Buenos Aires is classified as an Alpha− glob ...

and

Melbourne, Australia Melbourne ( , ; Boonwurrung/ or ) is the capital and most populous city of the Australian state of Victoria, and the second most-populous city in Australia, after Sydney. The city's name generally refers to a metropolitan area also known ...

, had to be closed temporarily due to volcanic ash. By 15 June a dense column of ash was still erupting 10 km into the air, with the ash cloud spreading across the Southern Hemisphere; scientists expected intensifying eruptions of Puyehue in the following days, and said the volcano showed no signs of slowing down.

Geothermal activity and exploration

Cordón Caulle is a major area of

geothermal activity Geothermal activity is a group of natural heat transfer processes, occurring on Earth's surface, caused by the presence of excess heat in the subsurface of the affected area, usually caused by the presence of an igneous intrusion underground. Geot ...

, as manifested by the several

hot spring A hot spring, hydrothermal spring, or geothermal spring is a Spring (hydrology), spring produced by the emergence of Geothermal activity, geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow ...

s, boiling springs,

solfatara A fumarole (or fumerole) is a vent in the surface of the Earth or another 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

s that develop on it. The geothermal system in Cordón Caulle consists of a vapour dominated system overlain by a more superficial steam heated

aquifer An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...

. The temperatures of the vapour systems range from and for the aquifer.Sepúlveda, Fabián; Lahsen, Alfredo; Dorsch, Klaus; Palacios, Carlos and Bender, Steffen. Geothermal Exploration in the Cordón Caulle Region, Southern Chile. Proceedings World Geothermal Congress 2005. The uppermost part of the geothermal system, at , is characterized by fumaroles and acid-

sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...

springs. Cordón Caulle is considered one of the main sites of geothermal exploration in Chile.

References

External links

* {{DEFAULTSORT:Puyehue-Cordon Caulle Active volcanoes Calderas of Chile Fissure vents Hot springs of Chile Landforms of Los Lagos Region Landforms of Los Ríos Region Mountain ranges of Chile Mountains of Chile Mountains of Los Lagos Region Mountains of Los Ríos Region South Volcanic Zone Stratovolcanoes of Chile VEI-5 volcanoes Volcanic deserts Volcanoes of Los Lagos Region Volcanoes of Los Ríos Region

Approach and ascent

Geography

Flora

Geologic history

Ancestral volcanoes

Volcanism during the Llanquihue glaciation

Postglacial volcanism

Recent eruptions

1921–1922, 1929 and 1934 eruptions

1960 eruption

1960–2011 period

2011–2012 eruption

Geothermal activity and exploration

See also

References

External links