|Elevation||6,377 m (20,922 ft) |
|Age of rock||Miocene-Holocene|
|Volcanic arc||Central Volcanic Zone|
|Last eruption||1,100 ± 100 or 700 ± 200 years ago|
Coropuna is a dormant stratovolcano in the southern Peruvian Andes that lies within the Central Volcanic Zone; it has several summits, the highest of which reaches an altitude of 6,377 metres (20,922 feet) above sea level. The volcano is located 150 kilometres (93 miles) from the city of Arequipa and is mostly made of ignimbrites and lava flows on a basement formed by earlier ignimbrites and lava flows, some of which may have been formed by Coropuna itself. Coropuna has been active for at least five million years, with the bulk of the current cone having formed during the Quaternary. Coropuna has had two or three Holocene eruptions 2,100 ± 200 and either 1,100 ± 100 or 700 ± 200 years ago which generated lava flows, and an additional eruption which may have occurred 6,000 years ago. Current activity occurs exclusively in the form of hot springs.
Coropuna is covered by a thick ice cap, the largest in the tropics, with a number of outlet glaciers; during the last glacial maximum it expanded to a size of over 500 square kilometres (190 sq mi). The ice cap is in retreat with some variation in retreat rates; 2018 estimates imply that the ice cap will persist into the 2120s. The retreat of the Coropuna glaciers threatens the water supply of tens of thousands of people, and interaction between volcanic activity and glacial effects has generated mudflows that could be a hazard to surrounding populations if the mountain were to erupt again. Because of this, the Peruvian geological agency INGEMMET monitors Coropuna and has published a hazard map for the volcano.
The mountain above 5 kilometres (3.1 miles) elevation is unvegetated but below this altitude there are various vegetation belts which include trees, peat bogs, grasses and also agricultural areas and pastures. People have lived on Coropuna for millennia. The mountain was considered sacred by the Inca and a number of archaeological sites have been discovered there including the Inca sites of Maucallacta and Acchaymarca; the mountain was considered to be one of the most important Inca religious sites in their realm and human sacrifices were offered to the mountain. The volcano also appears in legends.
In Quechua, the word puna means "plateau" and coro is a common component of toponyms such as at Coro Coro, Bolivia, but its etymological meaning is unclear. The name may mean Qoripuna, "Puna of Gold", "golden mountain", "cold, snowy" or "cut off at the top". The name is also spelled as Qhuru Puna. There is another volcano in the Andahua volcanic field with the name Coropuna, however it is unrelated to the Coropuna volcano.
Coropuna lies in the Andes of Peru, on the border between the Castilla and Condesuyos Provinces of the Arequipa Department.  Towns around the volcano belong to the Chuquibamba, Machaguay, Pampacolca and Viraco Districts. The volcano can be reached on paved roads that come to Andahua, either from Arequipa or through Aplao from the Pan American Highway. Roads also pass along the northern and western sides of the volcano.
Coropuna is part of the Cordillera Ampato mountain range, which contains almost a hundred glaciers, and are only 100 kilometres (62 mi) from the Pacific Ocean. More generally, Coropuna is part of the Andes, the longest mountain chain in the world which reaches from Tierra del Fuego in the south to Venezuela and runs along the coast of the Pacific Ocean.
The city of Arequipa is located 150 km (93 mi) southeast from the volcano. A number of villages surround the volcano, from northwest clockwise around the mountains these are Ocororuro, Arma, Maucallacta, Purhua Purhua, Chaupipuna, Utchu-Amayani, Torilla, Patilla, Pallca, Alco Llacta, Viques, Campanayo, Pecoy, Tagre, Pillcull, Chupacca, Chipcama, Cabra Grande, Pampacolca, Huncor, Huanjo, Santa Maria, Toma de Hayllaura and Huayllaura and more. There are no habitations above 5,200 metres (17,100 ft) elevation. Agriculture and animal husbandry are the most important economic activities in the region, but mining of precious metals takes place with copper and gold being prospected.
The volcano is part of the Central Volcanic Zone, one of the four volcanic belts of the Andes; the other three are the Northern Volcanic Zone, the Southern Volcanic Zone and the Austral Volcanic Zone. The Central Volcanic Zone includes the volcanoes of southern Peru and in total features about 44 stratovolcanoes, including many of the highest in the world and several glaciated volcanoes. Important volcanoes in southern Peru are from northwest to southeast Sara Sara, Solimana, Coropuna, Mismi, Ampato, Hualca Hualca, Sabancaya, Chachani, Misti, Ubinas, Huaynaputina, Tutupaca, Yucamane and Casiri. Aside from stratovolcanoes, large calderas of Neogene age also occur close to Coropuna. Sixteen volcanoes in Peru are considered to be active or potentially active, including Huaynaputina which in 1600 had a major eruption with a volcanic explosivity index of 6, which claimed over 1500 victims and caused devastation in southern Peru.
From above, Coropuna has a pear-shaped outline and is a 20 km (12 mi) long ridge with an east-west trend that features four separate domes forming summits and broad saddles between the domes; in addition there is a dome north of this line. A 5,558 m (18,235 ft) high subsidiary peak named Cerro Cuncaicha lies east of Coropuna and is a stratovolcano. Coropuna covers a surface area of 240 square kilometres (93 sq mi) and its domes rise about 3 kilometres (1.9 mi) above the surrounding plateau.
The volcano is formed by alternating layers of ignimbrite and lava; and consists of coalesced stratovolcanoes and seven separate coulees. Ice cover makes it difficult to discern the structure of the volcano; in total, about six separate structures have been counted. Six not readily recognizable summit craters have been identified on the volcano. Additional lava domes form a southeastward trending line on the southwestern side of the volcano and dikes crop out close to Lake Pallarcocha. It has further been suggested that Coropuna overlies the margin of a buried caldera.
The flanks of Coropuna consist of glaciated terrain, lava flows with gentle slopes and blocky lava cropping out from underneath the ice. Areas of hydrothermally altered rocks, lava flows, pyroclastic flows and areas covered by volcanic ash occur all around Coropuna. Wetlands can be found on the northern and southern side of the mountains. Coropuna is covered by snow and glacial activity has eroded the volcanic rocks, carving valleys into them or removing the rocks altogether. This process has generated U-shaped valleys such as Buenavista, Cospanja and Tuilaqui on the southern flank and Chaque, Mapa Mayo, Río Blanco, Torcom and Ullulo on the northern slopes.
Several collapse scarps are on the mountain, especially around its central sector. A sector collapse occurred on the southwestern flank and formed a landslide deposit as well as a horseshoe-shaped valley that was later filled by glaciers. Also on the southern side lahar deposits have been found in the Capiza River valley and appear to relate to Coropuna; at least eight such flows have been identified and some lahars have reached the Colca River valley. Lahars are mixtures of water and volcanic rocks that descend the valleys of volcanoes, and are dangerous phenomena owing to their high speed and density, causing large scale destruction and fatalities.
Lake Pallarcocha is situated on the southwestern flank on formerly glaciated terrain, and additional lakes lie on the northeastern side of Coropuna including Laguna Pucaylla. A number of streams and rivers originate on the mountain; clockwise around Coropuna these include Quebrada Chauqui-Huayco, Rio Amayani on the northern side, Quebrada Chinchina/Infernillo, Quebrada Jollpa, Quebrada Caspanja with the lake Laguna Caracara, Quebrada Buena Vista, Quebrada Tuallqui, Rio Testane on the southern flank, Rio de Huayllaura on the southwestern flank, Quebrada del Apacheta, Quebrada Sigue Chico and Quebrada Sepulturayoc on the western flank. The Rio Blanco and Rio Amayani eventually form the Rio Arma, while the Rio Capiza discharges water from Coropuna to the Colca River. During the dry season, most of these rivers do not carry substantial discharge.
The volcano is situated on a drainage divide; to the west the Rio Arma is a tributary of the Ocoña River, while to the east the Colca River is part of the Majes River watershed. An endorheic area that receives meltwater from the volcano also exists northeast from Coropuna, on Pampa Pucaylla where the lake of the same name is also located.
Coropuna rises 2 to 3.5 km (1.2 to 2.2 mi) above the surrounding terrain from a base elevation of 4,500 m (14,800 ft); the greatest elevation gains are found on the southern side where the Rio Llacllaja has incised the underlying basement almost to the foot of the volcano, forming sharp, amphitheater-like valleys. In general, many deep valleys cut into the flanks of the volcano and give the mountain an "impressive" topographic relief.
The region is characterized by high plateaus separated by deep canyons, including some of the world's deepest gorges that reach depths of 600–3,000 m (2,000–9,800 ft). Apart from river erosion, giant landslides have affected the Altiplano underneath of Coropuna, such as the Chuquibamba landslide, which took place over the last 120,000 years in the form of multiple collapse events within a fault-controlled basin.
Geomorphologically, Coropuna lies at the edge of the Altiplano on the Western Cordillera; in the Central Andes this mountain chain is split into two ranges - the western and the eastern Cordillera - separated by the Altiplano. The Pucuncho Basin and Firura volcano lie north of Coropuna, while Solimana volcano is located northwest from Coropuna. Sara Sara is another volcano in the area. A large lava dome lies northwest of Coropuna while Cerro Pumaranra, a 5,089 m (16,696 ft) eroded volcano is located to the northeast. Several lakes are situated on the eastern side of the volcano. 19 km (12 mi) west-southwest from Coropuna lies the 4,855 m (15,928 ft) high Antapuna, while the Andahua "valley of the volcanoes" is 20 km (12 mi) northeast-east of Coropuna.
Coropuna is the largest and highest volcano in Peru, the highest mountain in the Cordillera Ampato and the third-highest mountain in Peru. The volcano has been described as "imposing". The most commonly cited maximum height for the volcano is 6,377 m (20,922 ft),[a] which refers to the northwestern dome of the mountain[b] also known as Coropuna Casulla. Other estimates on Coropuna's maximum height are 6,380 m (20,930 ft), 6,425 metres (21,079 ft),[c] which would make it the 22nd highest mountain in the Andes, 6,426 m (21,083 ft) on the western summit, 6,446 m (21,148 ft) or 6,450 metres (21,160 ft) high. Varying snow elevations might lead to varying height estimates.
Estimates on the height of Coropuna have varied over time. In the 19th century Coropuna was one of the candidates for "highest mountain in Peru", with mountains in the Cordillera Blanca making up the other candidates, with the Mapa del Perú (Map of Peru) of Antonio Raimondi giving an estimated height of 6,949 m (22,799 ft). In 1910 it was believed that the volcano was over 7,000 m (23,000 ft) high and thus the highest mountain in South America ahead of Aconcagua, although a North American expedition during the preceding year had determined that Coropuna was not the highest mountain in Peru as it only found an elevation of 6,615 m (21,703 ft) and Huascaran is higher than this.
Coropuna has several (up to ten according to one count) summits which exceed 6,000 m (20,000 ft) elevation, and a 5,623 m (18,448 ft) high lower northern summit. Some summits have names, such as the 6,377 m (20,922 ft) high northern Coropuna Casulla, the 6,171 m (20,246 ft) high western Nevado Pallacocha, the 6,161 m (20,213 ft) high central Coropuna Central II, Escalera in the western sector of the volcano, Paiche in the central and Yana Ranra in the eastern sector.
Coropuna features an ice cap consisting of three ice domes and many glaciers. It is the largest ice cap of the tropics, which as of 2014[update] was 8.5 km (5.3 mi) wide and 11 km (6.8 mi) long; the Coropuna ice cap is larger than the ice cap at Quelccaya 250 km (160 mi) farther northeast which was considered to be the largest but has shrunk to a size less than Coropuna's. A subsidiary peak named Cerro Cuncaicha east of Coropuna has a small ice cap as well. In general, Peruvian glaciers form the bulk of the world's tropical glaciers. Aside from glaciers, perennial snow is also found at Coropuna.
On average, the ice cap of Coropuna is about 80.8 m (265 ft) thick, with maximum thicknesses exceeding 180 m (590 ft). In 2003-2004 the ice cap had a volume of about 3.69 cubic kilometres (0.89 cu mi) snow water equivalents. Ice cores have been taken from the Coropuna ice cap and from a summit crater; one of these ice cores covers a timespan beginning from 20,000 years ago.
Penitentes reaching heights of 2 m (6 ft 7 in) and seracs occur on the glaciers, while debris cover is rare. The ice cap also features ice falls and dangerous lakes. In the past lahars originated from the ice cap and left deposits at the bottom of valleys.
A number of glaciers are located in the ice cap, their number variously estimated to be between 23, 17 and 15. Some glaciers have been named; on the southwestern flank two glaciers are named Azufrioc 1 and 2, three Rio Blanco 1 through 3 and six Tuialqui 1 through 6. Eighteen separate accumulation areas have been found as well. There are no substantive valley glaciers presently on Coropuna and some glaciers, especially in the eastern side, emanate from cirques. The ongoing downward movement of the ice on Coropuna produces icequakes.
Glaciers descend to elevations of about 5,100–5,300 m (16,700–17,400 ft) on the southern and to about 5,500–5,800 m (18,000–19,000 ft) on the northern flank. This is higher than the freezing level, owing to the dry climate; the freezing level at Coropuna lies at about 4,900 m (16,100 ft) elevation. In 1955, the ice limits were located at elevations of 4,900 m (16,100 ft) on the southern and at 5,400 m (17,700 ft) on the northern flank.
Moraines on Coropuna crop out in particular on its northern and southern side and reach lengths of 3–8 km (1.9–5.0 mi), with longer moraines on the northern flank. In general, moraines on Coropuna are steep and have prominent crests as they are little eroded. Gray coloured, fresh moraines up to 500 m (1,600 ft) from the ice cap may reflect the position of the glaciers before the onset of glacier retreat, which has left small mounds that often contain ice between these moraines and the ice cap and small, discontinuous moraines.
Apart from normal glaciers, 78 rock glaciers have been counted on Coropuna, but only 11 of them are considered to be active. Permafrost has been reported as well on Coropuna. Cryoturbation, gelifluction, patterned grounds, solifluction and other periglacial landforms are noticeable at over 4,500 m (14,800 ft) elevation.
Measuring the surface area of Coropuna's ice cap is difficult as seasonal snow can be mistaken for ice, and different studies come to various conclusions about the retreat rate, due to the use of different time periods and methodological practices. However, all the various studies conclude that the net retreat trend is obvious and that the ice cap is diminishing. Retreat rates shortly before 2009 reached 13 percent in only 21 years. Between 1980 and 2014 the ice cap shrank at a rate of 0.409 square kilometres per year (0.158 sq mi/a) with a more recent estimate amounting to 0.5 square kilometres per year (0.19 sq mi/a), with a brief slowdown observed during the late 1990s and early 2000s. Total shrinkage has been estimated to amount to 26 percent between 1962 and 2000, and by 18 percent between 1955 and 2007.
The Coropuna ice cap retreat follows the pattern recorded elsewhere in Peru such as in the Cordillera Blanca, Cordillera Vilcanota and the mountains Ampato, Quelccaya and Sabancaya, and all of this retreat is attributed to global warming, and tends to increase during El Nino years owing to a drier climate. The glaciers lose mass through both sublimation and melting. This melt water rarely forms streams; though some are found with the Quebrada Ullulo on the northern side being the largest such stream.
In the past, before the first human settlement of the area, the ice cap on Coropuna was much larger than today, with its surface exceeding 500 square kilometres (190 sq mi) and glaciers descending to much lower elevations. Additionally, glaciers also expanded from the mountains Pumaranra, Pucaylla and Cuncaicha to the east of Coropuna covered the Pampa Pucaylla northeast from Coropuna and descended the Jellojello valley and other valleys to the east. Glacial valleys radiate from Coropuna, and glaciofluvial landforms are associated with moraines.
Regional climate oscillations are recorded in the ice masses of Coropuna. The glacial history of the volcano has been reconstructed with tephrochronology (using dated tephra layers such as those from the 1600 Huaynaputina eruptions), radiocarbon dating and surface exposure dating using helium-3. Three separate moraine generations and about five separate glacial stages have been recorded on the volcano. Glacial advances on Coropuna appear to be synchronous to advances of the ice sheets in the Northern Hemisphere. Glaciers developed on other mountains in the region as well.
During the Last Glacial Maximum (LGM) 25,000 - 20,000 years ago, valley glaciers on Coropuna were considerably longer than today and occupied glacial valleys up to 300 m (980 ft) deep and 7 km (4.3 mi) long. The glaciers formed tall moraines with as much as 100 m (330 ft) relief, 8 km (5.0 mi) in length, 10–5 m (33–16 ft) in width at the crest and a cover of boulders and gravel; they include both lateral moraines and terminal moraines where outlet glaciers ended. On the northern flank, moraine systems have been observed in the Santiago, Ullulo, Keaña, Queñua Ranra, Cuncaicha, Pommulca and Huajra Huire valleys, while the southeastern flank was covered by glaciers in the Yanaorco, Viques, Cospanja, Buena Vista Este, Buena Vista Oeste and Huasi valleys. Rock bars occur in some glacial valleys on the southern and southwestern side of the volcano. There are large cirques around Cerro Cuncaicha.
The LGM ice cap had an area of at least 365 km2 (141 sq mi), with glaciers descending to 3,780–4,540 m (12,400–14,900 ft) elevation, down to the north and the west, probably due to airflow-mediated variations in sublimation. The longest glacier reached a length of 12 km (7.5 mi) in the Quebrada Ullulo. The growth of the ice cap has been explained by a temperature drop of about 4.5–5.5 °C (8.1–9.9 °F) assuming constant precipitation and a 750 m (2,460 ft) decrease in elevation of the equilibrium line altitude. The retreat of these glaciers commenced between 12,000 and 11,000 years ago.
Ice has been present on Coropuna for at least 80,000 years, and at least two pre-LGM advances spread beyond the area that was covered with ice during the LGM, with an expansion occurring in particular in the eastern sector of the volcano. Moraines older than marine isotope stage 2 are widespread; old moraines close to the village of Viraco may be 40,000 - 45,000 years old and thus part of an older glaciation, and old dates of 47,000 - 31,000 and 61,000 - 37,000 years ago could reflect even larger glacier expansions during marine isotope stage 3 or 4.
Glaciers retreated after the end of the last glacial maximum 20,000 - 18,000 years ago and then re-expanded. During the Lateglacial, a group of moraines formed between the position of the LGM moraines and the position of the recent moraines, with one lateglacial advance dated to either 13,400 - 10,000 or 13,900 - 11,900 years ago. Full glacial conditions lasting until 10,000 - 9,000 years ago; minor advances took place about 13,000 - 9,000 and 6,000 years ago. The late glacial advances coincide with similar glacier expansions worldwide and some of them may correlate with the Younger Dryas cold period or the Antarctic Cold Reversal. During the Little Ice Age, glaciers on Coropuna did not expand much but some rock glaciers might have formed during that time. The glaciers descended to 4,900 m (16,100 ft) elevation.
Glaciers in Peru are important sources of water for local communities and for hydropower generation, especially during the dry season; their shrinkage is thus of concern. In the Cordillera Blanca it has been estimated that about 30 percent of the dry season runoff comes from glaciers. Meltwater from the glaciers on Coropuna sustains the baseflow of the rivers during dry periods; Coropuna is an important source of water for the valleys of the surrounding areas and for the desert-like piedmont, with an estimated 38,000 people depending directly or indirectly on water from Coropuna. This water supply is threatened by the retreat of the glaciers and would require costly mitigation measures to compensate for its reduction. The Peruvian government has assumed that the icecap will cease to be a source of water by 2025, although a more recent study concludes that the icecap will persist until about 2120.
Off the coast of Peru, the Nazca Plate subducts beneath the South America Plate at a rate of 9 centimetres per year (3.5 in/year). This subduction process along with the subduction of the Antarctic Plate also underneath the South America Plate is responsible for the volcanism in the Andes and the uplift of the mountain chain. The Andes in the area of Coropuna are still uplifting; in the Cordillera Occidental (Western Cordillera) uplift commenced about 50 million years ago, paused until 25 million years ago and increased substantially after about 10 million years ago.
The volcano is part of the volcanic arc of southern Peru and is considered to be a member of the Barroso volcanic arc. There are over six hundred volcanoes in southern Peru and the entire Cordillera Occidental from southern Peru to northern Chile is covered with volcanic rocks, although present-day volcanic activity is scarce. Many of the older volcanoes are deeply eroded by glaciation while younger volcanoes often still resemble cones.
Volcanic activity in the Andes occurred during three eras. The first was between 195 and 190 million years ago and formed the Chocolate Formation. The second between 78 and 50 million years ago generated the Toquepala Formation and the Andean batholiths. Volcanic activity in southern Peru commenced about 13 million years ago. One first volcanic unit after being eroded and folded was covered by a second lava and tuff unit which in turn was followed by the emplacement of large volcanoes. Ignimbritic and stratovolcanic activity - at times subdivided into a "rhyolitic" and an "andesitic" formation - alternated.
Coropuna is constructed atop of 14 million year old ignimbrites and lava flows of Neogene age. Individual ignimbrites crop out mainly in valleys, while they are buried beneath more recent volcanic products on the highlands. The volcanic basement includes the Miocene to Plio-Pleistocene Tacaza, Huaylillas, Sencca and Barroso Formations, the latter of which includes Coropuna itself. Below these formations lie the sedimentary Murco, Socosani Formations and the Grup Yura, which are sediments of Jurassic-Cretaceous age with intruded plutons of the same age; finally a Basal Complex of Precambrian age. The basement is cut by faults and lineaments such as the Pampacolca fault on the southern side of the volcano and the Pumaranra and Cerro Casulla lineaments which trend southeast-northwest and northeast-southwest, respectively. One east-west lineament may have influenced the recent volcanism and the alignment of Coropuna with Sara Sara, Solimana and El Misti may indicate a tectonic control on the volcano in general. Holocene normal faults especially on the southern flank of Coropuna have offset lava flows and streams.
The rocks erupted by Coropuna are dark brown or black and porphyritic and consist of andesite, dacite, rhyodacite, rhyolite, trachy-basaltic andesite, trachyandesite and trachydacite; recent lava flows have been of dacitic or trachydacitic composition. Phenocryst phases include amphibole, biotite, plagioclase, pyroxene and titanomagnetite. Aside from the volcanic rocks, deposits of salts, sulfur and travertine produced by hot springs occur on the southern flank.
They define a calc-alkaline potassium-rich suite which resembles that of other volcanoes in the region such as Tutupaca and Chilean volcanoes. It also contains large amounts of rubidium, strontium and barium and appears to have originated through complicated processes of crystallization and crustal interaction.
The volcano began growing either over five million years ago during the Pliocene, or during the late Miocene but most of the edifice developed during the Quaternary. Volcanic activity has been subdivided into two stages, the now mostly eroded Coropuna I which was characterized by explosive eruptions such as volcanic ash, pyroclastic flows and pumice but also lava flows, and the Coropuna II above 6,000 metres (20,000 ft) elevation which has erupted lava flows from the now snow-covered vents; a Coropuna III sequence has been described as well and the most recent eruption products have been described as the "Andahua Group". Other volcanoes in Peru such as Chachani and Sara Sara have similar histories. About 5.3 million years ago, the Sunjillpa volcano was active southwest from Coropuna, while Pumaranra is of Plio-Quaternary age.
A major ignimbrite eruption took place about two million years ago at Coropuna; its deposits have been identified west of the volcano and it led to the destruction of the edifice, which later re-formed on the remains of the old volcano.
In addition, the Upper Sencca ignimbrite, the Lower Sencca ignimbrite and the Chuquibamba (Huaylillas) ignimbrite may have originated here as well; the latter was produced by a volcanic explosivity index 7 class "super-eruption" between 14.3 and 13.2 million years ago. The Upper Sencca ignimbrites form a 10–30 m (33–98 ft) thick apron around Coropuna volcano and other regional volcanoes. These ignimbrites form a compound ignimbrite which was deposited between 2.09 and 1.76 million years ago; Coropuna appears to have formed on top of one of the Upper Sencca Ignimbrite vents.
Volcanic activity continued into the Pleistocene after a hiatus. Several lava flows on the western and central sides of Coropuna have been dated, yielding ages ranging from 410,000 ± 9,000 to 62,600 ± 4,300 years ago. During the last glacial maximum, Coropuna was inactive and moraines buried its lava flows but one or two tephra layers on a moraine close to the village of Viraco on the southern side have been dated to be about 41,000 and 30,000 - 31,000 years old. These ages correspond to radiocarbon ages of 37,370 ± 1,160 and 27,200 ± 300 years. These tephras may have originated in fissure eruptions associated with the three recent lava flows. In postglacial times lava bombs, lapilli and volcanic ash were emplaced on previously glaciated terrain. Pumice deposits may have formed during the Holocene.
No eruptions of Coropuna during historical or modern times are known and the volcano was formerly considered to be long extinct. However, young-looking aa lava/block lava flows were erupted during the Holocene and in part overlie late-glacial moraines; their vents are hidden beneath glacier ice and the flows have been affected by later glacial advances. These lava flows are found on the west-northwest, south-southeast and northeast side of the mountain:
The ages of the flows indicate an eastward shift in activity and the second two flows may have been erupted within 500 years from the same fissure, while the eruption of the first might be a consequence of the retreat of the ice cap. These lava flows are the most recent manifestation of volcanic activity and they imply that Coropuna is still active; it is thus considered to be a dormant volcano. There is no evidence of Holocene tephras in peat bog drill cores and volcanism at Coropuna since the last ice age has been primarily effusive.
The volcano is still hydrothermally active. Six hot springs are found on Coropuna, mostly on the southeastern foot, such as at Acopallpa, Antaura, Viques, Ccollpa, and Aguas Calientes and Huamaní Loma on the northern flank; temperatures range 51–18 °C (124–64 °F). With the exception of the last two which are situated in glacial terrain, these hot springs rise within valleys from rock fractures. Geochemical analyses of the water from these springs published in 2015 show no major variations in composition, implying a stable volcanic system. Whether solfataric or fumarolic activity occurs at Coropuna is unclear, and the thick glaciation indicates that the summit craters have no thermal activity.
Some of the hot springs on Coropuna are used for bathing. The volcano has been considered a potential site for geothermal power production but research published in 1998 considered the available energy of the Coropuna area insufficient for geothermal power production.
The first volcano activity report published in 2018 noted ongoing seismic activity involving volcano-tectonic earthquakes. Seismic swarms were observed at Coropuna after the 2001 southern Peru earthquake and were possibly triggered by the earthquake. Observations of deformation of the volcanic edifice have shown that gravitational instability and soil water absorption result in movements of part of the volcano but as a whole Coropuna shows no evidence of volcanic deformation.
The Peruvian Instituto Geológico Minero y Metalúrgico (INGEMMET) monitors Coropuna volcano for activity, using data such as the composition of hot spring waters and the shape of the volcano as estimated by satellite images, GPS and geodesy and five seismic stations. A volcanic hazard map has been published and there are regular status reports published by the Peruvian government. About 90,000 people live in risk areas, and the sites most at risk are towns on the steep southern valleys.
Together with El Misti, Sabancaya and Ubinas Coropuna is considered to be one of Peru's most dangerous volcanoes. The presence of an ice cap creates a hazard of lahars such as those that in 1985 killed over 23,000 at Nevado del Ruiz volcano in Colombia, if incandescent volcanic rocks melt the ice. At Coropuna the danger is further increased by the steep slopes around Coropuna and the concentration of people in the valleys; the terrain around the volcano has one of the greatest topographic reliefs in the world and a number of towns lie on the floor of the Majes valley, down to the Pacific Ocean where the important town Camana with 20,000 inhabitants lies. A number of towns could be threatened by lahars and according to the 2007 census about 110481 people lived in the provinces that span Coropuna and lie downstream of it, and lahars could reach all the way down to the coast although there is no evidence for past lahars of this size. In addition, infrastructure such as roads, antennas and small hydropower plants are found in the general area.
Lava flows are also a danger at Coropuna. Other hazards with lesser probabilities are directed blasts, lava dome collapses, fast-moving massive pyroclastic flows and flows of pumice and ash, lava bombs and shock waves.
Coropuna lies between the semihumid Altiplano and the arid western slope of the Andes and its climate is semiarid, with precipitation at 6,080 m (19,950 ft) elevation reaching 390 millimetres per year (15 in/year); other reported precipitation values range between 700 mm/a (28 in/year)-1,000 mm/a (39 in/year). Precipitation amount increases farther down to 226–560 mm/a (8.9–22.0 in/year) (semihumid) at 3,000–4,000 m (9,800–13,100 ft) elevation and subsequently decreases to 98–227 mm/a (3.9–8.9 in/year) (desert) at 2,000–3,000 m (6,600–9,800 ft) elevation.
Most precipitation is in the form of hail and snow. It falls mostly during the summer wet season between December and March when the ITCZ moves south and a summer monsoon is active over South America. Cold water brought from Antarctica along the Pacific Ocean by the Humboldt Current, the presence of a stable anticyclone and of a temperature inversion over the Pacific and the Andean rainshadow are responsible for this dryness; most precipitation is brought by easterly winds and comes from the Amazon and the Atlantic Ocean while the westerly winds that dominate during the dry season do not carry much moisture. Thus, humidity generally decreases in westward direction.
The amount of precipitation is modulated by the El Nino Southern Oscillation; during phases of El Nino the weather is drier, snow cover smaller and glacier retreat increases. Over longer timespans, increased precipitation in the region occurs when iceberg discharge and cooling occur in the North Atlantic; this was the case during the Heinrich events and the Younger Dryas when lakes formed on the Bolivian Altiplano: The Sajsi about 25,000 - 19,000 years ago, Tauca about 18,000 - 14,000 and Coipasa 13,000 - 11,000 years ago. Cold periods in the Southern Hemisphere such as the Antarctic Cold Reversal between 14,500 - 12,900 years ago may have pushed the polar front north and increased precipitation as well. Increased precipitation may have delayed the retreat of Coropuna's glaciers after the end of the last glacial maximum. The early Holocene was also moist at Coropuna, while the late Holocene beginning 5,200 years ago was drier there, with a pronounced dry period lasting between 5,200 and 3,000 years ago. Warm fluctuations between about 2,200 and 900 years ago and a cold fluctuation around 970 - 1010 AD are also recorded at Coropuna.
Temperatures decrease upwards from an average of 12–17 °C (54–63 °F) at 2,000–3,000 m (6,600–9,800 ft) elevation over a mean temperature of 7.8 °C (46.0 °F) at 3,000–4,000 m (9,800–13,100 ft) elevation and 0–6 °C (32–43 °F) at 4,000–5,200 m (13,100–17,100 ft) elevation to below zero above 5,200 m (17,100 ft). Temperatures fluctuate more over daily timescales than over seasonal ones when measured close to the glaciers. Temperatures can reach 2 °C (36 °F) to up to 5,000 m (16,000 ft) elevation. During the Little Ice Age, at 5,000–5,200 m (16,400–17,100 ft) elevation temperatures decreased 5 to 7 °C (41 to 45 °F). Southerly cold waves can sometimes reach Coropuna, leaving traces in ice cores in the form of southern pollen.
Most of the region is covered by puna vegetation, with the exception of isolated Polylepis woods southwest of the volcano and different vegetation types in the west and southeast. Peat bogs have been found especially on the southern and southwestern sides of the volcano, and some of these have been drilled to obtain sediment cores. Otherwise, agriculture is widespread around Coropuna. Birds such as the Andean condor and the vicuña occur in the region. Several butterfly species have been identified first at Coropuna.
Several distinct vegetation belts have been identified:
Numerous archeological sites lie on Coropuna, especially at the southern and northern bases of the volcano and on its western slope; some of these western sites are located on the ice cap. Among these are tombs such as chullpas. Proposals have been made to make the area of Coropuna including these archeological sites into a protected area.
After the coastal regions of Peru were first occupied between 11,000 - 9,000 years BC, hunter-gatherers first appear in the archeological record in the caves of Cavalca north and Pintasayoc south of the volcano. In the latter cave, rock paintings interpreted as being 7,000 - 3,000 years BC have been found. The first human activity at Coropuna in the Cuncaicha cave north of the volcano began shortly after the final retreat of glaciers on Coropuna. The region around the volcano was settled over the last 4,000 years.
A larger number of archaeological sites go back to the 2nd Intermediate Period and during the Inca era. The Inca expanded preexisting irrigation and terrace systems which are in part still existing today, including the highest irrigation system in the world which was possibly constructed on Coropuna to allow the cultivation of bitter potatoes, and built new constructions. Inca sites are often found at higher elevations than the preceding sites; the highest one is located at 5,700 m (18,700 ft) elevation and there is evidence of Inca presence to 6,200 m (20,300 ft) elevation. In addition, an important branch of the Inca road system passes by the western foot of Coropuna. The region was densely populated; the close location of the mountains and favorable climatic conditions facilitated its settlement.
As noted by Spanish chroniclers such as Pedro de Cieza de León, Coropuna played an important role in Inca religion and an important temple was situated there, possibly at Maucallacta. Pedro de Cieza de León considered Coropuna to be the fifth most important holy site of the Inca empire. One archeological site on the volcano may have been a stopover for religious ceremonies to its summit. Capacocha, a form of human sacrifice, were offered to the mountain and reportedly, in 1965, a mummy was found there.
Among the archeological sites at Coropuna is the important Inca site of Maucallacta, on the southwestern flank of mountain; some structures were built to evoke the appearance of the mountain. A royal residence, an oracle and a political unit were associated with Maucallacta; the oracle of Coropuna answered the rulers' queries year round, which is why they visited it with a certain frequency. The Maucallacta site was probably the most important one at Coropuna; in addition, the western summit today known as "La Nina" was apparently particularly important.
Another important site associated with Coropuna is Acchaymarca west of the volcano where about 280 Inca stone structures have been found; it is likely that a large number of pilgrims came there for ceremonies honouring the apus of Coropuna and Solimana.
Coropuna was considered to be the most important God (apu) of the region, the second-most important overall and a holy mountain; it was particularly important for the town of Cotahuasi. Sometimes Coropuna is seen as a male God while Solimana volcano was seen as a female one. Today, St Francis of Assisi is sometimes localized at the top of the mountain by pious people and the mountain is used in mortuary rites to this day.
The mountain was also considered to be an abode of the dead, where the deceased ended up,and was a large village of the departed. In different mythologies Coropuna is instead the starting point for the deceased on a journey to Surimana, or the place where the local populations originated from.
A poorly recorded set of legends is associated with Coropuna; one story narrates how a brother tried to deceive this mountain and some others and was turned into a deer, while another story narrates of a conflict between Coropuna and other local mountains against an interloping Inca. Finally, another account states that Coropuna and Solimana castrated a hunter who had killed an animal that was leading a pack transporting precious metals for the mountains.
The archeological findings made on Coropuna indicate that the Inca may have reached the summit in the past. 61-year old Annie Peck and Hiram Bingham III reached several summits of Coropuna in 1911; Annie Peck raised a banner saying "Votes for Women" on the summit she had ascended, which was slightly lower than the one reached by Bingham. This banner action was part of the women's suffrage campaigns that were taking place at that time, and meant to illustrate that women were just as capable as men of physical deeds. Since then, other summits of the mountain have been ascended as well.
The rugged area draws mountaineering. Coropuna is normally ascended from Laguna Pallarcocha, from where a route along the western rib and glacier slopes leads up to a foresummit and then to the main summit. Along this way, high camps can be set up at 5,600–5,800 metres (18,400–19,000 ft) elevation. Pallarcocha itself can be reached from a road that begins in the town of Chuquibamba.
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