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62-493: Some of the highest peaks of the province are Chachani , the Misti volcano and Pikchu Pikchu . Other mountains are listed below: The province is divided into twenty-nine districts ( Spanish : distritos , singular: distrito ). The province is inhabited by indigenous citizens of Aymara and Quechua descent. Spanish , however, is the language which the majority of the population (85.67%) learnt to speak in childhood, 1.64% of

124-747: A 4-inch thick ash layer can weigh 120-200 pounds and can get twice as heavy when wet. Wet ash also poses a risk to electronics due to its conductive nature. Dense clouds of hot volcanic ash can be expelled due to the collapse of an eruptive column , or laterally due to the partial collapse of a volcanic edifice or lava dome during explosive eruptions . These clouds are known as pyroclastic surges and in addition to ash , they contain hot lava , pumice , rock , and volcanic gas . Pyroclastic surges flow at speeds over 50 mph and are at temperatures between 200 °C – 700 °C. These surges can cause major damage to property and people in their path. Lava flows from stratovolcanoes are generally not

186-474: A fast moving mudflow . Lahars are typically about 60% sediment and 40% water. Depending on the abundance of volcanic debris the lahar can be fluid or thick like concrete. Lahars have the strength and speed to flatten structures and cause great bodily harm, gaining speeds up to dozens of kilometers per hour. In the 1985 eruption of Nevado del Ruiz in Colombia , Pyroclastic surges melted snow and ice atop

248-515: A final intermediate composition . When the magma nears the top surface, it pools in a magma chamber within the crust below the stratovolcano. The processes that trigger the final eruption remain a question for further research. Possible mechanisms include: These internal triggers may be modified by external triggers such as sector collapse , earthquakes , or interactions with groundwater . Some of these triggers operate only under limited conditions. For example, sector collapse (where part of

310-610: A large eruption occurred in 1600, Ticsani , Tutupaca , Yucamane and Casiri . Some of these volcanoes are among the highest in the world, and on average, there is one eruption of a Peruvian volcano every 13 years. The Peruvian volcanoes are part of the Central Volcanic Zone of the Andes, one of three separate volcanic belts in that mountain chain; the Central Volcanic Zone contains 44 named stratovolcanoes . Chachani

372-556: A present-day volume of about 154–248 cubic kilometres (37–59 cu mi); this makes Chachani one of the largest volcanoes of the Andes. Glacial erosion and landslides have affected the volcanic complex, forming cirques and U-shaped valleys and removing much of the original shape of the individual volcanoes. Some moraines have been overrun by lava flows. Chachani drains into the Rio Chili . The Quebrada Canchero, Quebrada Cabrería and Quebrada Traccra drain south to eastward into

434-739: A result of intraplate volcanism on oceanic islands far from plate boundaries. Examples are Teide in the Canary Islands , and Pico do Fogo in Cape Verde . Stratovolcanoes in the East African Rift include Ol Doinyo Lengai in Tanzania, and Longonot in Kenya. Subduction zone volcanoes form when hydrous minerals are pulled down into the mantle on the slab. These hydrous minerals, such as chlorite and serpentine , release their water into

496-461: A significant threat to humans or animals because the highly viscous lava moves slowly enough for everyone to evacuate. Most deaths attributed to lava are due to related causes such as explosions and asphyxiation from toxic gas . Lava flows can bury homes and farms in thick volcanic rock which greatly reduces property value. However, not all stratovolcanoes erupt viscous and sticky lava . Nyiragongo , near Lake Kivu in central Africa ,

558-552: A steep profile with a summit crater and explosive eruptions. Some have collapsed summit craters called calderas . The lava flowing from stratovolcanoes typically cools and solidifies before spreading far, due to high viscosity . The magma forming this lava is often felsic , having high to intermediate levels of silica (as in rhyolite , dacite , or andesite ), with lesser amounts of less viscous mafic magma . Extensive felsic lava flows are uncommon, but can travel as far as 8 km (5 mi). The term composite volcano

620-406: Is a concern at Chachani. Chachani is the protector mountain spirit of Cayma The people of Arequipa sometimes refer to Chachani as the "father" of El Misti (Pichu Pichu is the "mother") and ascribed to it the ability to influence the gender of newborn children, making them daughters. The Inca worshipped Chachani and its neighbouring mountains and turned its summit into a mountain sanctuary that

682-527: Is a passive release of gas during periods of dormancy. As per the above examples, while eruptions like Mount Unzen have caused deaths and local damage, the impact of the June 1991 eruption of Mount Pinatubo was seen globally. The eruptive columns reached heights of 40 km and dumped 17 megatons of SO 2 into the lower stratosphere . The aerosols that formed from the sulfur dioxide (SO 2 ), carbon dioxide (CO 2 ), and other gases dispersed around

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744-458: Is an about 2 kilometres (1.2 mi) high and 17 kilometres (11 mi) wide complex of lava domes , stratovolcanoes and volcanic cones ; the highest summit is 6,057 metres (19,872 ft) high, making Chachani the 84th highest peak in the Andes. The Chachani complex has an arcuate shape encompassing both the main Chachani volcano and the 5,784 metres (18,976 ft) high Nocarane to

806-634: Is made up of more than 12 edifices. The Colorado lava domes which are also known as Cerro Penones in turn are located northwest from Nocarane. To the south of Chachani lie the Airport Domes, a 8 kilometres (5.0 mi) wide lava shield with two discernible vents and a pristine appearance. The lava shield consists of overlapping lava flows with a wavy and rugose texture and a steep front which reaches heights of 1.2 kilometres (0.75 mi); evidently these were formed by viscous lava flows. A volcanic caldera associated with widespread ignimbrites in

868-638: Is occasionally covered in snow. The zero degree elevation at Chachani lies at about 5,000 metres (16,000 ft). The diurnal temperature range is large and can reach 20 °C (36 °F), while ground temperatures are much more stable and higher than air temperatures. A meteorological observatory installed by the Harvard College Observatory was active on the mountain in the latest 19th century. From 3,500 to 3,900 metres (11,500 to 12,800 ft) elevation cacti , herbs , Peruvian feather grass , yareta but also lichens and mosses grow on

930-451: Is the most famous example of a hazardous stratovolcano eruption. It completely smothered the nearby ancient cities of Pompeii and Herculaneum with thick deposits of pyroclastic surges and pumice ranging from 6–7 meters deep. Pompeii had 10,000-20,000 inhabitants at the time of eruption. Mount Vesuvius is recognized as one of the most dangerous of the world's volcanoes, due to its capacity for powerful explosive eruptions coupled with

992-450: Is typically between 700 and 1,200 °C (1,300-2,200 °F). Volcanic bombs are masses of unconsolidated rock and lava that are ejected during an eruption. Volcanic bombs are classified as larger than 64mm (2.5 inches). Anything below 64mm is classified as a volcanic block . When erupted Bombs are still molten and partially cool and solidify on their descent. They can form ribbon or oval shapes that can also flatten on impact with

1054-990: Is used because the strata are usually mixed and uneven instead of neat layers. They are among the most common types of volcanoes; more than 700 stratovolcanoes have erupted lava during the Holocene Epoch (the last 11,700 years), and many older, now extinct, stratovolcanoes erupted lava as far back as Archean times. Stratovolcanoes are typically found in subduction zones but they also occur in other geological settings. Two examples of stratovolcanoes famous for catastrophic eruptions are Krakatoa in Indonesia (which erupted in 1883 claiming 36,000 lives) and Mount Vesuvius in Italy (which erupted in 79 A.D killing an estimated 2,000 people). In modern times, Mount St. Helens (1980) in Washington State , US, and Mount Pinatubo (1991) in

1116-403: Is very dangerous because its magma has an unusually low silica content , making it much less viscous than other stratovolcanoes. Low viscosity lava can generate massive lava fountains , while lava of thicker viscosity can solidify within the vent, creating a volcanic plug . Volcanic plugs can trap gas and create pressure in the magma chamber, resulting in violent eruptions. Lava

1178-646: The Andes of southern Peru , 22 kilometres (14 mi) northwest of Arequipa and north of the Arequipa Airport ; the city of Arequipa is situated on the foot of Chachani and El Misti volcanoes. The road from Arequipa to Chivay runs along the southeastern foot of Chachani, and a dirt road reaches to an elevation of 5,000 metres (16,000 ft). It is considered to be one of the most easily climbed mountains between 6,000 - 7,000 m high, although acclimatization and good physical health are required to ascend it. In

1240-573: The Holocene . Chachani has erupted andesite and dacite , which define a potassium -rich calc-alkaline suite with unusual adakite characteristics; adakites are magmas that form when the downgoing plate in a subduction setting melts. Phenocrysts include augite , biotite , hornblende and hypersthene ; the rhyolites of the Arequipa ignimbrites additionally contain ilmenite , magnetite , plagioclase , quartz and sanidine . The composition of

1302-632: The Huaylillas Ignimbrite of southern Peru. Later, during the Quaternary the Chachani volcanic complex grew in the caldera. The older activity formed the older volcanoes Chingana northeast, Estribo east and Nocarane north of Chachani as well as the Colorado lava domes north-northwest from Nocarane and the volcanoes Chachani Base and El Angel; argon-argon dating has yielded ages ranging between 1,000,000 - 500,000 years ago for these volcanoes. Later

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1364-573: The Philippines have erupted catastrophically, but with fewer deaths. Stratovolcanoes are common at subduction zones , forming chains and clusters along plate tectonic boundaries where an oceanic crust plate is drawn under a continental crust plate (continental arc volcanism, e.g. Cascade Range , Andes , Campania ) or another oceanic crust plate ( island arc volcanism, e.g. Japan , Philippines , Aleutian Islands ). Stratovolcanoes also occur in some other geological settings, for example as

1426-523: The Sencca Formation and the "Barroso" volcanics developed; Chachani is classified as part of the Barroso volcanics although the oldest volcanism might belong to the "Sillapaca" unit. The terrain of the volcano is formed by volcanic rocks of Eocene to recent age, which overlie a Precambrian basement and include widespread Neogene - Quaternary ignimbrites . Chachani straddles the margin between

1488-507: The airport , hydropower plants and reservoirs are within range of Chachani and human settlement has spread around its base. As of 2023 , about 349000 people live on its slopes and infrastructure such as schools are within the volcano's reach. The western suburbs of Arequipa are 3 kilometres (1.9 mi) below and less than 25 kilometres (16 mi) away from the volcano and in case of renewed eruptions they would be threatened by pyroclastic flows . In addition, melting ice and snow on

1550-891: The magma is too viscous to allow easy escape of volcanic gases . As a consequence, the tremendous internal pressures of the trapped volcanic gases remain and intermingle in the pasty magma . Following the breaching of the vent and the opening of the crater, the magma degasses explosively. The magma and gases blast out with high speed and full force. Since 1600 CE , nearly 300,000 people have been killed by volcanic eruptions . Most deaths were caused by pyroclastic flows and lahars , deadly hazards that often accompany explosive eruptions of subduction-zone stratovolcanoes. Pyroclastic flows are swift, avalanche-like, ground-sweeping, incandescent mixtures of hot volcanic debris, fine ash , fragmented lava , and superheated gases that can travel at speeds over 150 km/h (90 mph). Around 30,000 people were killed by pyroclastic flows during

1612-443: The mantle which decreases its melting point by 60 to 100 °C. The release of water from hydrated minerals is termed " dewatering ", and occurs at specific pressures and temperatures for each mineral, as the plate descends to greater depths. This allows the mantle to partially melt and generate magma . This is called flux melting . The magma then rises through the crust , incorporating silica-rich crustal rock, leading to

1674-532: The 18–20 cubic kilometres (4.3–4.8 cu mi) 1.65 million years old Arequipa Airport, and less certainly the 1.5 cubic kilometres (0.36 cu mi) early Pleistocene Yura Tuff as well as the Capillune Formation ignimbrites appear to have been erupted by Chachani or (in the case of the Yura Tuff) from a vent north of it. Together with lava flows these form the "Pre-Chachani" units and probably are

1736-607: The 1902 eruption of Mount Pelée on the island of Martinique in the Caribbean . During March and April 1982, El Chichón in the State of Chiapas in southeastern Mexico , erupted 3 times, causing the worst volcanic disaster in that country's history and killied more than 2,000 people in pyroclastic flows . Two Decade Volcanoes that erupted in 1991 provide examples of stratovolcano hazards. On 15 June, Mount Pinatubo erupted and caused an ash cloud to shoot 40 km (25 mi) into

1798-481: The 1982 eruption of Galunggung in Java , British Airways Flight 9 flew into the ash cloud, causing it to sustain temporary engine failure and structural damage. Although no crashes have happened due to ash, more than 60, mostly commercial aircraft , have been damaged. Some of these incidents resulted in emergency landings. Ashfalls are a threat to health when inhaled and are also a threat to property. A square yard of

1860-585: The 5,321 m (17,457 ft) high Andean volcano. The ensuing lahar killed 25,000 people and flooded the city of Armero and nearby settlements. As a volcano forms, several different gases mix with magma in the volcanic chamber. During an eruption the gases are then released into the atmosphere which can lead to toxic human exposure. The most abundant of these gases is H 2 O ( water ) followed by CO 2 ( carbon dioxide ), SO 2 ( sulfur dioxide ), H 2 S ( hydrogen sulfide ), and HF ( hydrogen fluoride ). If at concentrations of more than 3% in

1922-710: The Arequipa area may be located underneath Chachani; to the north its outline is marked by a 20 kilometres (12 mi) wide amphitheatre while its southern part is continuous with the Arequipa depression and is generally poorly recognizable. The El Misti volcano later arose on the margin of the Chachani caldera, where it intersects the border of the Altiplano . The volcanic complex is formed mainly by aa and block lava flows that rarely reach lengths of about 10 kilometres (6.2 mi); additionally pyroclastic flows and tephra occur. The volcanic complex covers an area of about 600 square kilometres (230 sq mi) and has

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1984-546: The Cabrería lava domes; formerly the Airport Domes/Los Angeles/Pampa de Palacio were considered to be the youngest and of Holocene age. However, Volcancillo may be even younger, and a post-glacial lava flow descends the western slope of Chachani between Chachani and Nocarane and phreatic eruptions may have formed Holocene-age craters on Chachani. No historical eruptions are known at the volcanic complex, and

2046-589: The La Joya, Arequipa Airport and Yura Tuff ignimbrites; afterwards the volcanic group proper grew in the caldera until about 56,500 years ago. There have not been any eruptions during historical time, but the volcano is considered to be only dormant and due to its closeness to the city of Arequipa is considered high risk. The name means "brave" in Aymara or "mountain of man"/"mountain of male"; alternative spellings "Cacheni" and "Charchani" are also known. The volcano lies in

2108-627: The Rio Siguas. The volcano underwent five stages of glaciation in the past. During the last glacial maximum extensive glaciers formed well-developed moraines at 3,150–3,600 metres (10,330–11,810 ft) elevation; lateral moraines marking the limit of glaciation are located at 3,440 metres (11,290 ft) elevation on the southern flank. Glaciers may have also formed during the Little Ice Age , where there are moraines at 5,100–5,300 metres (16,700–17,400 ft) elevation; presently however

2170-816: The air, when breathed in CO 2 can cause dizziness and difficulty breathing. At more than 15% concentration CO 2 causes death. CO 2 can settle into depressions in the land, leading to deadly, odorless pockets of gas. SO 2 classified as a respiratory, skin, and eye irritant if come into contact with. It is known for its pungent egg smell and role in ozone depletion and has the potential to cause acid rain downwind of an eruption. H 2 S has an even stronger odor than SO 2 as well as being even more toxic. Exposure for less than an hour at concentrations of over 500 ppm causes death. HF and similar species can coat ash particles and once deposited can poison soil and water. Gases are also emitted during volcanic degassing, which

2232-741: The air. It produced large pyroclastic surges and lahar floods that caused a lot of damage to the surrounding area. Pinatubo , located in Central Luzon just 90 km (56 mi) west-northwest of Manila , had been dormant for six centuries before the 1991 eruption. This eruption was one of the 2nd largest in the 20th century. It produced a large volcanic ash cloud that affected global temperatures, lowering them in areas as much as .5 °C. The volcanic ash cloud consisted of 22 million tons of SO 2 which combined with water droplets to create sulfuric acid . In 1991 Japan's Unzen Volcano also erupted, after 200 years of inactivity. It's located on

2294-451: The city of Arequipa . Part of the Central Volcanic Zone of the Andes, it is 6,057 metres (19,872 ft) above sea level. It consists of several lava domes and individual volcanoes such as Nocarane , along with lava shields such as the Airport Domes. Underneath Chachani lies a caldera . During the Pliocene and early Pleistocene , the volcanic group produced large ignimbrites such as

2356-533: The date of the last activity is likewise unclear. The existence of solfataras in the summit region and of hot springs at Socosani and Yura has been reported, and frequent seismic activity occurs on Chachani's southwestern flank; this activity may relate to either geothermal or tectonic phenomena. Currently, the volcano is considered to be dormant . Occasionally, mudflows descend its slopes and cause damages at lower elevations. The city of Arequipa with about one million inhabitants and infrastructure such as

2418-581: The downgoing Nazca plate falls steeply into the mantle. Volcanic activity in the Chachani region appears to have begun during the Cretaceous - Paleocene in the form of the "Toquepala" volcanics. The oldest volcanic rocks of the Western Cordillera are known under the name "Tacaza", and underwent erosion and folding before the next phase which is known as "Sillapaca". Finally, during the Miocene - Quaternary

2480-540: The flank of a volcano collapses in a massive landslide) can only trigger the eruption of a very shallow magma chamber . Magma differentiation and thermal expansion also are ineffective as triggers for eruptions from deep magma chambers . In recorded history , explosive eruptions at subduction zone ( convergent-boundary ) volcanoes have posed the greatest hazard to civilizations. Subduction-zone stratovolcanoes, such as Mount St. Helens , Mount Etna and Mount Pinatubo , typically erupt with explosive force because

2542-439: The foot of tall cliffs . Some of them (about six in total) are still active and are located above 4,810 metres (15,780 ft) elevation, while the lowest inactive ones end at 4,160 metres (13,650 ft) elevation. Permafrost is expected to be continuous above 5,420 metres (17,780 ft) with discontinuous occurrence above 5,050 metres (16,570 ft). Other periglacial phenomena such as needle ice are also encountered on

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2604-478: The ground. Volcanic Bombs are associated with Strombolian and Vulcanian eruptions and basaltic lava . Ejection velocities ranging from 200 to 400 m/s have been recorded causing volcanic bombs to be destructive. Lahars (from a Javanese term for volcanic mudflows) are a mixture of volcanic debris and water. Lahars can result from heavy rainfall during or before the eruption or interaction with ice and snow. Meltwater mixes with volcanic debris causing

2666-458: The high population density of the surrounding Metropolitan Naples area (totaling about 3.6 million inhabitants). In addition to potentially affecting the climate, volcanic ash clouds from explosive eruptions pose a serious hazard to aviation . Volcanic ash clouds consist of ash which is made of silt or sand sized pieces of rock, mineral, volcanic glass . Ash grains are jagged, abrasive, and don't dissolve in water. For example, during

2728-466: The higher-elevation Altiplano and the Arequipa basin at lower altitude. The younger El Misti volcano lies southeast of Chachani, across the Rio Chili . Other volcanoes in the region are Ampato and Jollojello northwest, Baquetane, Hucullani and Nevado Calcha north, Yanarico east and Pichu Pichu southeast from Chachani. Of these, Misti, Pichu Pichu and Chachani are aligned on normal faults that trend northwest–southeast and has been active during

2790-500: The island of Kyushu about 40 km (25 mi) east of Nagasaki . Beginning in June, a newly formed lava dome repeatedly collapsed. This generated a pyroclastic flow that flowed down the mountain's slopes at speeds as high as 200 km/h (120 mph). The 1991 eruption of Mount Unzen was one of the worst volcanic disasters in Japan's history, once killing more than 15,000 people in 1792. The eruption of Mount Vesuvius in 79 AD

2852-525: The largest eruptions experienced by Chachani. They occur in the wider region of Chachani and crop out in the Arequipa area and in river valleys. Their emplacement took place in the form of fast-moving hot streams of rock. An additional ignimbrite is the 13 million years old Miocene Rio Chili Ignimbrite; the vents of the Miocene units are unknown and the Rio Chili Ignimbrite appears to be related to

2914-456: The late 19th century, the good sight from Chachani was remarked upon. Politically, it lies in the Cayma, Yura and Cerro Colorado districts. Volcanoes in the southern part of Peru include from north to south Auquihuato , Firura , Coropuna , Andagua volcanic field , Sabancaya , Ampato , Chachani, El Misti , Pichu Pichu , Ubinas which has erupted intermittently since 1954, Huaynaputina where

2976-465: The mountain lacks glaciers and only has a snowfield . In general, glaciers in the tropical Andes have been shrinking after the end of the Little Ice Age, and especially after the 1970s. Permafrost and rock glaciers however still exist at Chachani, especially close to Nocarane, and reach lengths of 1.8 kilometres (1.1 mi); they are characterized by lobate appearances and their location at

3038-431: The north of Chachani, while the 5,484 metres (17,992 ft) high La Horqueta together with El Rodado to its west and Chachani proper to its east forms an east–west trending ridge. La Horqueta has a young appearance and resembles an ash cone with a crater . Additional peaks are the northerly 5,852 metres (19,199 ft) high los Ángeles and the southeasterly 5,820 metres (19,090 ft) high Trigo. In total, Chachani

3100-570: The other two hazard scenarios. Chachani is considered to be a high-risk volcano and the Geophysical Institute of Peru in 2018 installed a monitoring station on Chachani. Several volcano hazard map exist: One shows three levels of danger depending on the distance from the edifice, the other two show areas threatened by mudflows and pyroclastic fall . Chachani is monitored with seismometers and tiltmeters . Apart from eruptions, volcano-induced pollution of neighbouring water resources

3162-449: The residents started speaking using the Aymara language and 12.35% using Quechua ( 2007 Peru Census ). 16°23′56″S 71°32′13″W  /  16.398822°S 71.536883°W  / -16.398822; -71.536883 This Arequipa Region geography article is a stub . You can help Misplaced Pages by expanding it . Chachani Chachani is a volcanic group in southern Peru , 22 kilometres (14 mi) northwest of

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3224-519: The river which flows around the southeastern side of Chachani and has cut a canyon between Chachani and El Misti . The Rio Sumbay, one of its tributaries, runs along the eastern side of Chachani. The Rio Yura flows southward along the western side of Chachani, and upon reaching the then westward-flowing Rio Chili becomes the Rio Vitor , which eventually discharges into the Pacific Ocean together with

3286-460: The size of Mount Pinatubo affected the weather for a few years; with warmer winters and cooler summers observed. A similar phenomenon occurred in the April 1815, the eruption of Mount Tambora on Sumbawa island in Indonesia . The Mount Tambora eruption is recognized as the most powerful eruption in recorded history. Its eruption cloud lowered global temperatures as much as 0.4 to 0.7 °C. In

3348-472: The slopes of Chachani and other regional volcanoes. Vegetation is scarce to absent above 4,500 metres (14,800 ft) elevation, and much of its lower slopes were stripped of their vegetation during the colonial era. The dry soils are not suitable for agriculture . Part of the volcano is in the Salinas y Aguada Blanca National Reserve . Lizards on the mountain are the highest-altitude known reptile population in

3410-428: The summit could generate mudflows , and pyroclastic flows , lava flows and tephra falls are additional hazards. Four hazard scenarios have been established: An effusive eruption would cause serious physical damage, but only little threat to humans. Lava dome forming eruptions may give rise to pyroclastics, but there is no evidence of such pyroclastic deposits. Pyroclastic flow - and Plinian eruptions constitute

3472-691: The volcanic complex. Subduction of the Nazca Plate beneath the South America Plate occurs at a rate of 4.6 centimetres per year (1.8 in/year); the subduction process is responsible for the volcanism and earthquake activity of the region. In the Andes, volcanism is distributed between three volcanic belts, the Northern Volcanic Zone , the Central Volcanic Zone and the Southern Volcanic Zone which coincide with segments where

3534-461: The volcanic rocks has varied over the lifespan of Chachani, sometimes rocks of basaltic andesite composition were erupted as well while the younger volcanoes are usually more homogeneous; this was paralleled by a decrease in the eruption rate. Under the influence of the cold Humboldt Current and the subtropical ridge , the region features an arid climate with less than 100 millimetres (3.9 in) annual precipitation in Arequipa. The mountain

3596-554: The volcanoes El Rodado, La Horqueta and Chachani ( c. 130,000 - 131,000 years ago) formed as a west–east alignment, along with the Uyupampa lava field (about 230,000 - 280,000 years ago) far west from Chachani, the Airport Domes south (between 290,000 - 400,000 years ago), the Cabrería lava domes south-southeast and the Volcancillo dome northeast from Chachani. The youngest reported date of 56,500 ± 31,600 years ago has been obtained on

3658-403: The white "sillar" rocks that were used in construction of the famous buildings of colonial-era Arequipa, which is also known as the "white city". Stratovolcano A stratovolcano , also known as a composite volcano , is a conical volcano built up by many alternating layers ( strata ) of hardened lava and tephra . Unlike shield volcanoes , stratovolcanoes are characterized by

3720-645: The world. The oldest volcanic formations linked to Chachani are the so-called " sillars ", which are rhyolitic pyroclastic flows / ignimbrites containing pumice beds. These ignimbrites include the La Joya Ignimbrite of Pliocene age, the Plio-Quaternary Arequipa Airport Ignimbrite and the Quaternary Yura Tuff and Capillune Formation . The 16–24 cubic kilometres (3.8–5.8 cu mi) 4.8 million years old La Joya,

3782-412: The world. The SO 2 in this cloud combined with water (both of volcanic and atmospheric origin) and formed sulfuric acid , blocking a portion of the sunlight from reaching the troposphere . This caused the global temperature to decrease by about 0.4 °C (0.72 °F) from 1992 to 1993. These aerosols caused the ozone layer to reach the lowest concentrations recorded at that time. An eruption

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3844-410: Was later destroyed by sulfur mining and plundering to the point that no trace of archeological sites can be found, such as e.g. walls. Nevertheless, evidence of Inka human sacrifice known as capacocha was found during archeological expeditions; a finding from 1896 is the earliest known finding of such a sacrifice. Chachani was reportedly mined for sulfur during the colonial era and for

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