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141-572: The highest elevation in the district is the Ubinas volcano. Other mountains are listed below: This Moquegua Region geography article is a stub . You can help Misplaced Pages by expanding it . 16°23′12″S 70°51′21″W  /  16.3867°S 70.8559°W  / -16.3867; -70.8559 Ubinas Ubinas is an active stratovolcano in the Moquegua Region of southern Peru , approximately 60 kilometres (37 mi) east of

282-449: A 65-square-kilometre (25 sq mi) circular surface at the margin of a high plateau . Volcanic ash and some lava flows cover the terrain north and east of Ubinas. Four lava domes crop out around the volcano and may be related to it. The Ubinas and Para valleys border the volcano in its southeastern sector; the difference in elevation between the floor of the Ubinas valley and

423-544: A ceremonial area was reported in 2024. Professor S. I. Bailey from the Harvard College Observatory in 1893 installed the world's highest weather station on Misti. The station was one of several high-altitude stations built at the time, which aimed to investigate the atmosphere at such high altitudes; additionally, the Observatory performed research on the response of the human body to high altitudes and on

564-425: A deposit with five separate layers of pumice, ash and lapilli. More eruptions identified by tephrochronology took place 1,890 ± 70, 7,480 ± 40, 11,280 ± 70, 11,480 ± 220 and 14,690 ± 200 years ago, yielding scoria and pyroclastic flows. The various explosive eruptions of Ubinas have deposited material as far as 15 kilometres (9.3 mi) away from the volcano. Landslides also took place in this time, including

705-468: A hydrothermal system. The fumaroles outside of the summit crater are colder, with temperatures of 50–80 °C (122–176 °F), and do not smell of sulfur. Fumarolic vents are surrounded by concentric deposits of anhydrite close to the vent, gypsum at some distance, and sulfur in the colder vents. Other minerals are ammonium sulfate , hematite , ralstonite , soda alum and sodium chloride . Elemental compositions and isotope ratios indicate that

846-521: A new monitoring station for the volcano was inaugurated. In May 2009 and April 2010, two exercise evacuations of several suburbs of Arequipa were carried out. In 2013, the Peruvian Volcano Observatory (OVI) was inaugurated in Arequipa; it monitors Misti, Ubinas, Ticsani and other Peruvian volcanoes. As of 2021 , the monitoring network on Misti includes seismometers , equipment that measures

987-419: A report on the activity of Ubinas. When there are indications of increased volcanic activity, it can recommend that the local government raise the volcano hazard level . Hazard maps were created during the 2006 eruptive event to show the relative risk in various locations around the volcano, which is graded in a three-zone scheme with one high-risk, one intermediate-risk and one low-risk zone. A contingency map

1128-482: A small size. An underground magmatic connection between Ubinas and Huaynaputina was postulated already by Antonio Vázquez de Espinosa after the 1600 eruption of the latter volcano, which was the largest historical eruption in the Andes and had an enormous impact, including causing a cold summer in the northern hemisphere. The basement of Ubinas consists of volcanic and sedimentary rocks. The sedimentary rocks include

1269-423: A vegetation form called pajonal , which consists of creeping plants, grasses and shrubs made up of high Andean vegetation. Small lakes and areas of waterlogged soil form wetlands called bofedales , in which aquatic plants and rosette-forming plants grow; both bofedales and pajonal also feature cushion plants . The upper sector of Ubinas is vegetation-free. Animal species have been described mainly in

1410-525: Is arid overall, but during the summer wet-season rainfall can cause landslides at lower elevation, and the upper parts of the volcano including the caldera can receive a snow cover. Weather data are available for the town of Ubinas at 3,200 metres (10,500 ft) elevation: the average temperature is 9–11 °C (48–52 °F) and the average annual precipitation is about 300–360 millimetres per year (12–14 in/year). The present-day snow line exceeds 5,400 metres (17,700 ft) elevation, but during

1551-458: Is a dormant volcano located in the Andes mountains in southern Peru , rising above Peru's second-largest city, Arequipa . It is a conical volcano with two nested summit craters , the inner one of which contains a volcanic plug or lava dome with active fumaroles . The summit of the volcano lies on the margin of the outer crater and is 5,822 metres (19,101 ft) above sea level. Snow falls on

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1692-422: Is a conical, truncated stratovolcano with upper slopes that reach angles of up to 45 degrees, and more gently sloping lower flanks. The more gently sloping lower part of the volcano is also known as Ubinas I and the steeper upper part as Ubinas II. The southern flank is cut by a noticeable notch, which is probably not an eruption vent and may have been formed by mudflows and rockslides . Due to weathering ,

1833-414: Is also the principal water resource for the city. Roads leaving the city cross the river on bridges. According to Italian geographer Cumin 1925, there were three small man-made structures of unknown origin in the crater. He noted that they were known since 1677. Inka ceremonial platforms on the summit associated with human sacrifices were probably destroyed by human activities around 1900 AD , although

1974-508: Is at 5,822 metres (19,101 ft) on the northwestern outer crater rim; an iron cross marks the highest point. Other mountains of the Western Cordillera , including Ubinas and Pichu Pichu , can be seen from the summit. The volcano is about 20 kilometres (12 mi) wide and rises abruptly from the surrounding terrain. Estimates of the edifice's volume range reach 150 cubic kilometres (36 cu mi), but more likely its volume

2115-416: Is constrained to 2,060–1,920 years before present ; ages of 2,300 BP are probably too old. The eruption produced about 0.4 cubic kilometres (0.096 cu mi) dense rock equivalents of rock and probably lasted a few hours. The eruption had a volcanic explosivity index of 4 or 5. The eruption was probably triggered when fresh andesitic magma entered a pre-existent rhyolitic body. Magma rose through

2256-534: Is constructed on mudflow and pyroclastic flow deposits of the volcano and all the valleys that drain Misti pass directly or indirectly through Arequipa. At least 220,000 people live on the alluvial fans and in the ravines on the southern side of Misti, and are threatened by floods, mudflows and pyroclastic flows emanating from the volcano that can be channelled through the ravines. Individual threats from Misti include: Hazards at Misti are not limited to volcanism. During

2397-1269: Is contentious. The outer summit crater probably formed during this eruption. Tephra layers in the Sallalli and (in this case with less certainty) Mucurca peat bogs close to Sabancaya, and (tentatively) for an ice core in the Antarctic Plateau in Antarctica , are attributed to this eruption. This is the only Plinian eruption during the Holocene. After the 2 ka eruption, activity was limited to small Vulcanian eruptions , mudflows and tephra fallout, including scoria and volcanic ash. Dating has yielded ages of 330, 340, 520, 620, 1035 and 1,300 years before present for several such events. Mudflows took place 1,035 ± 45, 520 ± 25, 340 ± 40 and 330 ± 60 years ago and left 5–15-metre (16–49 ft) thick deposits. Not all of these mudflows are associated with eruptions. Pyroclastic flows and ash falls were emplaced 1,290 ± 100 and 620 ± 50 years ago. The last eruption took place in AD 1440–1470 and produced about 0.006 cubic kilometres (0.0014 cu mi) of ash. It

2538-436: Is erupted, with mixing particularly important during the last 21,000 years. A recharge of the magma chamber may have occurred at some point before 2000 AD. The overall rate of magma supply is 0.63 cubic kilometres per kiloare (0.15 cu mi/ka), comparable to other stratovolcanoes in volcanic arcs, but with brief surges reaching about 2.1 cubic kilometres per kiloare (0.50 cu mi/ka) and an increased rate during

2679-583: Is high enough to melt the sulfur and the fumarolic gases can ignite. Hot springs occur at the foot of the volcano. These include the Humaluso/Umaluso spring north and the Agua Salada, Bedoya/La Bedoya, Calle Cuzco, Charcani V, Chilina Norte, Chilina Sur, Jésus, Ojo de Milagro, Puente de Fierro, Sabandia, Tingo, Yumina and Zemanat south and southwest of Misti. The hottest of these is the Charcani V spring in

2820-408: Is in the southeastern part of the outer crater. The inner crater cuts across metre-thick ash and scoria deposits and historical lava domes and is rimmed by scoria. In the crater is a 120-metre (390 ft) wide and 15-metre (49 ft) high volcanic plug /lava dome, covered with cracks, boulders and fumarolic sulfur deposits; it is fumarolically active. The highest point of the volcano

2961-530: Is likely that the summit caldera formed during this time period, before 9,700 years ago. Over the last 7,500 years, volcanic activity has been characterized mainly by various kinds of explosive eruptions. These eruptions have expelled less than 0.1 cubic kilometres (0.024 cu mi) of material each time and left widespread deposits of ash, volcanic blocks and lapilli . A Plinian eruption occurred 980 ± 60 years BP and expelled 2.8 cubic kilometres (0.67 cu mi) of pumice and tephra, which has formed

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3102-417: Is made up of pyroclastic rocks and stubby lava flows , which form a 2.2-kilometre (1.4 mi) thick pile. On the northwestern foot, there is a rhyolitic landform named "Hijo de Misti" ("son of Misti"). Misti is surrounded by a fan of volcanic debris, which covers an area of 200 square kilometres (77 sq mi) on Misti and extends 25 kilometres (16 mi) from the volcano. On the southern side,

3243-547: Is no evidence that a supposed Inka settlement was destroyed by this eruption, but the local population fled and the Inka had to resettle the area. Along with other volcanic eruptions around that time and the beginning Spörer Minimum , the AD 1440–1470 eruption of Misti may have affected global climate conditions. In 1600, the volcano was covered by ash from the Huaynaputina. There is no clear evidence of historical eruptions, while

3384-575: Is no memory of the hazards of volcanic activity, unlike the hazards of earthquake. Before the eruption of Ubinas in 2006–2007, volcanic hazards drew little attention from the Peruvian state and there was little awareness in Arequipa. The volcano is frequently considered a protective figure and not as a threat. A number of people associate volcanoes with lava flows and neglect other volcanic hazards. Beginning in 2005, INGEMMET began monitoring volcanoes in Peru;

3525-529: Is one of the most dangerous volcanoes in the world, as it lies less than 20 kilometres (12 mi) from Arequipa. The city's population exceeds one million people and its northeastern suburbs have expanded on to the slopes of the volcano. The narrow valleys on western and southern flanks are a particular threat, as mudflows and pyroclastic flows can be channelled into the urban area and into important infrastructure, like hydropower plants . Even moderate eruptions can deposit volcanic ash and tephra over most of

3666-402: Is only 90 cubic kilometres (22 cu mi) or 40 cubic kilometres (9.6 cu mi). It is notably asymmetric, with the western side more heavily eroded and featuring older rocks than the eastern side. The western rim of the outer crater is about 150 metres (490 ft) higher than the southern. Underneath the Misti cone is an older, eroded stratovolcano ("Misti 1"). The stratovolcano

3807-433: Is steeper and rises 900 metres (3,000 ft) above the Ubinas I shield. It consists mainly of 20–40-metre-thick (66–131 ft) lava flows but also several lava domes with accompanying block-and-ash flows, all of which formed between 261,000 ± 10,000 and 142,000 ± 30,000 years ago. A lack of more recent volcanic outcrops suggests a period of dormancy lasting until 25,000–14,700 years ago during which glaciation took place on

3948-642: Is the genitive of hupi . Local inhabitants believed that Ubinas was infested by demons and the souls of people who had fallen from God. The volcano is also known as Uvillas or Uvinas. Ubinas lies in the Ubinas District of the General Sánchez Cerro Province , Moquegua Region of Peru , 60 kilometres (37 mi) east of Arequipa in the Peruvian Western Cordillera . Like other Peruvian volcanoes, Ubinas belongs to

4089-448: Is the first hazard map of a Peruvian volcano. These maps serve to mitigate volcano hazards and to inform local development. A 3D map was published in 2018. In November 2010, the municipality of Arequipa decreed that the hazard map would have to be considered in future city zoning decisions. Three different scenarios of future eruptions have been evaluated. The first envisages a small eruption, similar to recent activity at Sabancaya or

4230-545: Is the major product of historical eruptions. There is a trend for more recent volcanic events to produce more diverse rocks than the early eruptions, probably owing to a change in the magma supply regime; after 25,000–14,700 years ago magma supply increased and became more irregular. Otherwise, the magma supply rate at Ubinas amounts to about 0.18–0.13 cubic kilometres per millennium (0.043–0.031 cu mi/ka), with an average rate of 0.15 cubic kilometres per millennium (0.036 cu mi/ka). Ubinas started to develop in

4371-584: Is visible in satellite images as a temperature anomaly of about 6 K (11 °F). Water is the most important component of the fumarole gases, followed by carbon dioxide , sulfur dioxide , hydrogen sulfide and hydrogen . The gases are highly acidic, containing hydrogen chloride and hydrogen sulfide. Fumarole temperatures have varied through the years, generally they are between 125–310 °C (257–590 °F) with peaks of 430 °C (806 °F). The present-day (21st century) fumarole gases appear to derive directly from magma, with no interaction with

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4512-428: The 2007 Peru earthquake . Over time old fumarolic vents shut down and new vents develop, but the configuration of the dome vents is stable over time. The fumarolic activity is correlated to earth tides . The region has a semi-arid climate with temperate temperatures; the annual mean temperature in Arequipa is 13.7 °C (56.7 °F). Temperatures decrease with elevation; in 1910 monthly mean temperatures at

4653-522: The 2014 Iquique earthquake , culminating in an explosive eruption on April 19, 2014. Volcanic activity decreased afterwards until September 2014. The eruptions were accompanied by earthquakes, rumbling noises from the volcano, ash fall and the forceful ejection of large blocks. In light of the volcanic activity, Peru declared a state of emergency in August 2013 and evacuated the village of Querapi at Ubinas, whose population returned in 2016; The evacuation of

4794-1148: The Central Volcanic Zone of the Andes. The Central Volcanic Zone is one of four volcanic belts in the Andes; the others are the Northern Volcanic Zone , the Southern Volcanic Zone , and the Austral Volcanic Zone . The Central Volcanic Zone is 1,500 kilometres (930 mi) long, and 69 of its volcanoes have been active in the Holocene epoch. Peruvian volcanoes include stratovolcanoes , which are typically active for less than 500,000 years, long-lived clusters of lava domes, and monogenetic volcanic fields . Historical eruptions have been recorded at seven Peruvian volcanoes: El Misti , Huaynaputina , Sabancaya , Ticsani , Tutupaca , Ubinas, and Yucamane . The volcanoes Ampato , Casiri , Chachani , Coropuna , and Sara Sara are dormant . Reaching an elevation of 5,672 metres (18,609 ft), Ubinas

4935-730: The Jurassic Chocholate Formation , the Socosani Formation and the Yura Group . The oldest volcanic rocks of the Matalaque Volcanics date to the Late Cretaceous and crop out east and southeast of Ubinas, far away from the volcano. Most of the volcanics in proximity to Ubinas are the younger, Eocene -to- Oligocene Tacaza Group and the more restricted Miocene - Pliocene Barroso Group , which directly underlies

5076-577: The Nazca Plate subducts under South America at a rate of 5–6 centimetres per year (2.0–2.4 in/year). The subduction is responsible for the volcanism of the CVZ, as the downgoing slab releases fluids that chemically modify the overlying mantle , causing it to produce melts. Most Peruvian volcanoes have produced potassium -rich andesitic magmas, derived from the mantle and further modified by fractional crystallization and assimilation of material from

5217-461: The Pleistocene epoch it descended to about 4,900 metres (16,100 ft). Vegetation at 3,400–4,200 metres (11,200–13,800 ft) elevation consists of grassland, bushes and low trees such as Buddleja coriacea , Escallonia myrtilloides , Polylepis besseri and Ribes brachybotrys forming a shrub vegetation in valleys. Farther up, between 4,200–4,700 metres (13,800–15,400 ft) lies

5358-464: The Puno and Tacna Regions , as well as Bolivia and Argentina . Since then the volcano has been active with ash and steam emissions, earthquakes and lahars. In May 2023, an increase of seismic activity preceded a new eruption that commenced on 22 June 2023. This eruption petered out at the end of the year, while lahars descended its slopes. Hazards stemming from volcanic activity at Ubinas are mainly

5499-549: The Spanish conquest : Andagua volcanic field , Huaynaputina, Sabancaya and Ubinas, and possibly Ticsani , Tutupaca and Yucamane . Other Peruvian volcanoes in the CVZ are Ampato , Casiri , Coropuna , Huambo volcanic field , Purupuruni and Sara Sara . Ubinas is the most active volcano in Peru, having erupted 24 times since 1550. The 1600 eruption of Huaynaputina claimed more than 1,000 casualties; recent eruptions of Sabancaya 1987–1998 and Ubinas 2006–2007 had severe impacts on

5640-511: The solar eclipse of April 16, 1893 . Misti was in its time the highest permanently inhabited location on Earth. Another weather station, named "Mt. Blanc Station", was installed at the base of the volcano after 1888. Both were shut down in 1901 when the Observatory decided to only maintain a station in Arequipa; subsequently storms have erased any trace of the summit observatory. Observation of physics phenomena, such as cosmic ray measurements, were sporadically carried out on Misti during

5781-424: The wet season , Arequipa is frequently flooded. Heavy metals , presumably from Misti and Chachani, have been found in river water. In 2001, there was neither emergency planning nor land use planning around Misti; the 2002–2015 development plan mentioned volcanic hazards but did not envisage any specific measures. The last eruption of Misti had taken place shortly before the foundation of Arequipa, and thus there

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5922-402: The "high risk" zone. The "intermediate risk" zone surrounds the "high risk" zone, including the lower slopes of neighbouring mountains and most of the northeastern parts of Arequipa. The "low risk" zone in turn surrounds the "intermediate risk" zone and includes the rest of the city. Additional maps show areas at risk of tephra fallout and of being flooded by mudflows. The hazard map of Misti

6063-834: The 1 cubic kilometre (0.24 cu mi) collapse more than 3,670 ± 60 years ago. Ubinas is the most active volcano in Peru and one of the most active in the Central Volcanic Zone; as of 2023 at least 27 explosive eruptions have occurred since the 16th century at an average rate of one eruption every twenty to thirty-three years. Events are recorded from 1550, 1599, 1600, 1662, 1667, 1677, 1778, 1784, 1826, 1830, 1862, 1865, 1867, 1869, 1906, 1907, 1912, 1923, 1936, 1937, 1951, 1956, 1969, 1996, 2006–2009, 2013–2016, 2016–2017 and 2019. Most of these eruptions consisted of emissions of ash and gas, sometimes accompanied by explosions, while more intense events such as in 1667 also produced scoria falls and pyroclastic flows. The 1667 eruption

6204-569: The 1440–1470 AD eruption of Misti. Ash fall would occur around the volcano, reaching 5 centimetres (2.0 in) in the urban area and shutting down the Arequipa Airport , landslides could damage the dams on the Rio Chili, and mudflows would descend the southern slopes. The second scenario involves an eruption like the 2 ka eruption. Thicker ash falls (exceeding 10 centimetres (3.9 in)) could cause buildings to collapse, and pyroclastic flows down

6345-407: The 17 January 2008. It defines three hazard categories: A red "high risk" zone, an orange "intermediate risk" zone and a yellow "low risk" zone. These are defined by the risk of debris flows , lava flows, mudflows, pyroclastic flows, and tephra fallout. The "high risk" zone encompasses the entire volcanic cone, its immediate surroundings and the valleys that emanate from it. Parts of Arequipa lie in

6486-466: The 2006–2007 eruption sequence involved the ejection of large volcanic bombs at high speed and the emission of small quantities of ash. Gas and ash columns were emitted between April and October 2006 and reached heights of about 3–4 kilometres (1.9–2.5 mi). Volcanically induced melting of snow that had fallen on the summit during the 2006–2007 summer induced a mudflow in January 2007 that descended into

6627-552: The 20th century. Misti rises about 3.5 kilometres (2.2 mi) above Arequipa, the second-largest city in Peru, and is the best known volcano of Peru. The Inka empire 's Condesuyos province included the volcano; presently it is in the Arequipa Department . The mountain is visible from the sea. The volcanoes of Peru are part of the Andean Central Volcanic Zone (CVZ), one of the four volcanic belts of

6768-544: The 4.89 ± 0.02 million years old La Joya ignimbrite or "sillar", the 1.65 ± 0.04 million years old Aeropuerto or Sencca ignimbrite, and the 1.02 million years old Yura Tuff and Capillune Formation. They were erupted from multiple calderas , one of which is now buried under Chachani. The ignimbrites are covered by volcanic sedimentary rocks and debris from the sector collapse of Pichu Pichu. Misti has erupted mainly andesite , while dacite and rhyolite are less common. There are reports of trachyandesite erupted during

6909-471: The Andes; the others are the Northern Volcanic Zone , the Southern Volcanic Zone and the Austral Volcanic Zone . The CVZ extends for 1,000 kilometres (620 mi) from southern Peru through Bolivia to northern Argentina and Chile. Volcanoes are numerous in the CVZ, but most are poorly known due to the low population density of much of the Central Andes. Several Peruvian volcanoes have been active since

7050-429: The Central Andes 43,000 years ago. Between 50,000 and 40,000 years ago, the summit of Misti collapsed one or more times above 4,400 metres (14,400 ft) elevation, forming a 6-by-5-kilometre (3.7 mi × 3.1 mi) caldera. Intense pyroclastic eruptions yielded ignimbrites with volumes of 3–5 cubic kilometres (0.72–1.20 cu mi), which cover an area of 100 square kilometres (39 sq mi) on

7191-514: The Global Volcanism Program reports a last eruption in 1985. Mudflows descended the southern valleys until the 17th century. Phreatic eruptions may have taken place in 1577, on the 2 May 1677, 9 July 1784, 28 July 1787 and 10 October 1787. Questionable eruptions are recorded in 1542, 1599, August 1826, August 1830, 1831, September 1869, March 1870. They probably constitute fumarolic activity and often took place after heavy precipitation;

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7332-513: The Holocene eruptions. Rhyolites and dacites are associated with explosive eruptions. The volcanic rocks are subdivided into several classes: Pyroxene - amphibole andesites, amphibole andesites, amphibole dacites and amphibole rhyolites; mica has also been reported. The rocks define a potassium-rich calc-alkaline suite typical for Peruvian volcanoes. Phenocrysts include amphibole, augite , biotite , enstatite , plagioclase and titanomagnetite . Magma composition has varied over time and

7473-567: The Pacific Ocean and Lake Titicaca. Radiocarbon dating has identified eruptions 8,140, 6,390, 5,200, 4,750, 3,800 and 2,050 years ago; the 3,800 eruption deposited fallout on Nevado Mismi more than 90 kilometres (56 mi) northwest of Misti. The Global Volcanism Program lists eruptions in 310 BCE ± 100, 2230 BCE ± 200, 3510 BCE ± 150, 4020 BCE ± 200, 5390 BCE ± 75 and 7190 BCE ± 150. The last major explosive eruption – one or several events – took place about 2,000 years ago. The date

7614-457: The Peruvian geological service INGEMMET , which has published a volcano hazard map for Ubinas and regular volcanic activity reports. The historian and geographer Mariano Felipe Paz Soldán relates the name Ubinas to two terms in two different languages. In the indigenous language Quechua , uina means "to stuff" or "to fill", and uiña is translated as "to grow" or "to increase". In Aymara , hupi means "weep" or "murmur"; hupina

7755-589: The Rio Chili gorge; it is also the closest to the volcano, being only 6 kilometres (3.7 mi) from the crater. The Jésus and Umaluso springs produce gas bubbles. The springs are fed by a low-temperature geothermal system that mostly produces alkaline waters containing bicarbonate , chloride and sulfate . Their waters appear to originate through the mixing of freshwater, magmatic water and chloride-rich deep water. Many of these springs form artificial pools or have water intakes, and several are monitored by INGEMMET for changes in activity. High soil temperatures on

7896-467: The Rio Socabaya and Rio Chili, forming temporary lakes south and north of the volcano that were later affected by earthquakes. Between 24,000 and 12,000 years ago ice fields formed on Chachani and Misti during the last glacial maximum; tephra fell on ice and was reworked by meltwater. Two eruptions 13,700 and 11,300 years ago produced pyroclastic surges that extended 12 kilometres (7.5 mi) away from

8037-580: The Toquepala arc 91 – c. 45 million years ago over the Andahuaylas-Anta c. 45–30 million years ago, the Huaylillas 24–10 million years ago, the two Barroso arcs 10–1 million years ago, to the recent arc in the last million years. The switching between the volcanic arcs was accompanied by northeastward or southwestward shifts of the zone of main volcanic activity. Furthermore, there was little relief in

8178-557: The Ubinas River valley. Volcanic activity— degassing and of Vulcanian eruptions —decreased until late 2009. This eruption was probably triggered by the entry of fresh magma in the magma plumbing system and the subsequent interaction of ascending magmas with the hydrothermal system of Ubinas. Beginning in July 2009, eruptive activity decreased considerably, being replaced with steady fumarolic emissions. Despite its record of activity, Ubinas

8319-439: The Ubinas mountain. Even older basement rocks include Paleoproterozoic plutons and the sedimentary Yura Group of Jurassic to Cretaceous age. A depression, whose margin is cut by landslide scars, cuts into the basement southeast of Ubinas and contains the Ubinas valley. Faults cut across the volcano and create unstable areas, especially in its southern sector, and NNW-SSE trending geological lineaments have influenced

8460-508: The austral summer (December to March) and amounts to 89.1 millimetres per year (3.51 in/year), a 1910 study found most precipitation to be in the form of snow or hail. During the wet season, rainstorms and flash floods erode the volcanic debris deposits. The snow cover rapidly melts away during the dry season. The El Niño-Southern Oscillation and sea surface temperatures in the Atlantic and Pacific Oceans govern annual rainfall. After

8601-401: The caldera floor is covered by lava flows and pyroclastic debris from explosive eruptions. It contains one or two ash cones with a triangle-shaped crater 400 metres (1,300 ft) wide and 300 metres (980 ft) deep; its walls are fractured and hydrothermally altered. Geophysical surveys have indicated the presence of an even larger buried caldera in Ubinas. A debris avalanche on

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8742-410: The cities of El Alto , La Joya and agricultural areas. A Plinian eruption would require the evacuation of Arequipa. Other hazard scenarios are the emissions of short lava flows , the formation and collapse of lava domes and the collapse of part of the volcanic edifice. Fumaroles on Misti occur in three locations: on the volcanic plug, the northern/northeastern walls of the inner crater, and on

8883-431: The city of Arequipa . Part of the Central Volcanic Zone of the Andes , it rises 5,672 metres (18,609 ft) above sea level. The volcano's summit is cut by a 1.4-kilometre-wide (0.87 mi) and 150-metre-deep (490 ft) caldera , which itself contains a smaller crater . Below the summit, Ubinas has the shape of an upwards-steepening cone with a prominent notch on the southern side. The gently sloping lower part of

9024-485: The city. Until 2005, there was little awareness or monitoring of the volcano. Since then, the Peruvian INGEMMET has set up a volcano observatory in Arequipa, run public awareness campaigns on the dangers of renewed eruptions and published a hazard map. The Inca viewed the volcano as a threat and during the 1440–1470 eruption offered human sacrifices ( capacocha ) on its summit and that of its neighbours to calm

9165-432: The closest town to it. Agriculture and animal husbandry are the most important economic activities in these towns, agriculture prevailing at lower elevations. Water reservoirs and mining projects also exist in the wider region. Paved roads run along the northern and southern-southwestern foot of Ubinas, connecting towns close to the volcano to Arequipa and allowing access to the volcano over its western flank. Off

9306-499: The composition and temperature of hot springs and fumaroles, and sensors for movements or deformations of the edifice. These efforts have yielded an increased awareness of the dangers posed by Misti, which is now being increasingly perceived as an active volcano. Efforts have been made to slow the growth of the northern suburbs of Arequipa, which are closest to Misti. A volcano hazard map was developed in 2005 by numerous local and international organizations, and officially presented on

9447-431: The cone, hot springs and fumaroles indicate that Misti contains a hydrothermal system. Electric potential measurements indicate that the system appears to be confined between faults or to the older caldera. The activity has not been stable over time; after the 2001 southern Peru earthquake flow at the Charcani V spring and the temperature of the crater emissions increased noticeably. Water temperatures decreased after

9588-530: The context of the National Reserve; they include various birds and camelids such as alpacas , guanacos , llamas and vicuñas . Sulfur deposits in the crater of Ubinas were considered among the most important sulfur deposits in Peru and were mined in the 19th century. Ubinas has been considered a potential place for geothermal energy production. Its eruptions between 2006–2017 have stimulated research on this volcano. El Misti Misti

9729-557: The crater after wet seasons; another lake formed in 2016 after the crater floor was covered by the ongoing eruptions with impermeable material. Acid springs occur in the crater, and their water is capable of corroding silicon after a few hours' exposure. Lake Piscococha is located on the volcano's western foot and during December–April receives meltwater from its slopes, while the Para River and Sacuaya River flow past its eastern and southern slopes, respectively. Other rivers on

9870-456: The crater. Ubinas persistently emanates smoke, and lahars which have damaged fields , irrigation canals and paths have been recorded, such as the 2016 lahars caused by early 2016 precipitation events which mobilized ash that had fallen over the previous years. These lahars destroyed local water supplies and left the Matalaque and Ubinas districts temporarily isolated. The first episode of

10011-632: The districts surrounding the volcano, then in September of the same year an eruption generated a 4-kilometre-high (2.5 mi) eruption column that produced ash fall in the region, leading to evacuations. On 18 June 2019, earthquake activity increased and a new eruption commenced on 24 June, with eruption columns rising 5 kilometres (3.1 mi) above the summit crater. The most energetic eruption episode took place on 19 July 2019 with three major explosions. The explosions and ash emissions triggered evacuations and impacted 29,703 people in various districts of

10152-411: The edifice and expelled part of the hydrothermal system, causing initial phreatic eruptions . Tephra rained down around the edifice, with pumice falling 25 kilometres (16 mi) from the volcano. Owing to magma mixing, the pumice deposits have an appearance resembling chocolate and vanilla swirls. Eventually, the conduit fully cleared and a 29-kilometre (18 mi) high eruption column rose above

10293-523: The edifice slip southward over time. A northwest-southeast trending fault system includes the Huanca fault at Chachani and the Chili fault on Misti. The faults were active during the Holocene , offsetting tephra deposits, and may have provided a pathway for magma to ascend and form the volcanoes of Arequipa. Other faults include north- and northeast-trending faults, which are inactive but could have influenced

10434-556: The edifice. They eventually join to the Rio Chili west and Rio Andamayo south of Misti; the Andamayo joins the Chili south of Arequipa. Quebrada San Lazaro and Quebrada Huarangual have formed alluvial fans at the foot of the volcano. The quebradas (dry valleys) carry water during the wet season in November–December and March–April. During the wet season, snow can cover an area of 1–7 square kilometres (0.39–2.70 sq mi) on

10575-837: The emplacement of numerous large ignimbrites . During the Cretaceous - Paleogene , the Toquepala Group of volcanics was emplaced. The Tacaza Arc is the source of the Huaylillas Formation and the Barroso Group of the Sencca Formation. The Nazca fracture zone on the Nazca Plate projects under Misti. Misti is part of the Western Cordillera of the Andes. It is the youngest of a group of three Plio-Pleistocene volcanoes;

10716-410: The fallout from explosive eruptions, lahars of different origins, large landslides that can generate debris flows and pyroclastic flows. Small explosive eruptions are the most likely occurrences at Ubinas, while large Plinian eruptions are considerably less likely. The area of the cone itself is the area most likely to be affected by volcanic phenomena, while pyroclastic flows and lahars are a danger for

10857-480: The first Altiplano polities to influence the region or whether previous cultures played a role, but by the arrival of the Spanish the area was densely populated. The pre-Hispanic people built canals, roads and buildings in the area where Arequipa is today. The city itself was founded on 15 August 1540. Misti is the house mountain of Arequipa, appearing on the seal of the city for example. The old roads heading from Arequipa to Chivay and Juliaca run along

10998-405: The first monitoring equipment was targeted at the Charcani V hot spring . Later the monitoring was extended to other hot springs and to fumaroles in the crater; the latter both visually from Arequipa and in the crater. Monitoring of seismic activity commenced in 2005. Beginning in 2008 geodesic measurement stations were installed on the northeastern and southern slopes of the volcano. In 2012,

11139-495: The foot of the volcano and debris and ignimbrite deposits in the south and southeast of Ubinas, and it forms a 600-metre-high (2,000 ft) shield . It was later cut on its southern side by a debris avalanche that probably occurred over 376,000 years ago. The last activity of Ubinas I generated more than four units of pyroclastic flows , with a total volume of about 1.8 cubic kilometres (0.43 cu mi), and possibly an old caldera 269,000 ± 16,000 years ago. Ubinas II

11280-602: The formation of the Rio Chili canyon . The crust under the volcano is 55 kilometres (34 mi) thick. The basement under Misti crops out in the Rio Chili gorge. It consists of Proterozoic rocks of the Arequipa Terrane , which are more than a billion years old, Jurassic sediments of the Socosani Formation and Yura Group, and the Cretaceous-Paleogene La Caldera batholith . The batholith forms

11421-408: The fumarole deposits are derived from the leaching of volcanic rocks and the water from precipitation. The chemistry of the deposits changed between 1967 and 2018, with decreasing zinc and increasing lead concentrations, concomitant with a warming of the fumarolic system that may be due to the arrival of new magma in the volcano during the 20th century. Sometimes the temperature of the fumaroles

11562-454: The genesis of this magma suite. Lava composition has changed over time, dacites being represented mainly during the Ubinas II stage while stage I yielded mostly andesites. Silica content has decreased over time, with two phases of more silicic eruptions in the mid- and late Holocene. Holocene explosive eruptions were fed by silicic magma chambers that are now inactive as basaltic andesite

11703-400: The growth of the current mountain in two phases. Among the recent eruptions was the 2006–2007 event, which produced eruption columns and led to ash fall in the region, resulting in health issues and evacuations. During the most recent activity, from 2013 to 2017, a lava flow formed inside the crater, and further ash falls led to renewed evacuations of surrounding towns. Ubinas is monitored by

11844-457: The hills south of Arequipa. These formations are covered by rhyodacitic ignimbrites known as "sillars". They are between 13.8 and 2.4 million years old; the older are part of the Huaylillas Formation and the younger of the Barroso Arc. Individual ignimbrites crop out in the Rio Chili gorge and include the 300-metre (980 ft) thick Río Chili ignimbrite from 13.19 ± 0.09 million years ago,

11985-431: The last 21,000 years. Misti is a young volcano. It developed in four stages, numbered 1 through 4; a pre-Misti volcano may have formed the southwestern debris avalanche. On average, sub- Plinian eruptions take place every 2,000–4,000 years, while ash fallout occurs every 500–1,500 years and large ignimbrite -producing eruptions every 20,000–10,000 years. Outcrops showing the stratigraphy of Misti are found mainly in

12126-515: The local populations. The volcano is a young, symmetric cone with 30° degree slopes and a nested summit crater . The outer crater has a diameter of 950 metres (3,120 ft) or 835 metres (2,740 ft) and is 120 metres (390 ft) deep. There is a gap in the southwestern rim, almost to the bottom of the crater; otherwise the inner crater walls are nearly vertical and consist of lapilli , lava and volcanic ash . The 550-metre (1,800 ft) wide and 200-metre (660 ft) deep inner crater

12267-452: The magmas of Misti is a complicated process, involving the arrival of new magma, assimilation of crustal material, and fractional crystallization. Initially mantle -derived melts pool in a reservoir at the base of the crust , where they assimilate crustal material and undergo fractional crystallization. Afterwards they ascend to a shallower reservoir, where they interact with Proterozoic gneisses . Assimilation of basement rocks gave rise to

12408-427: The middle and late Pleistocene epoch. The oldest pre-Ubinas volcanics crop out north and south of the volcano and include the volcanoes Parhuane Grande and Parhuane Chico directly to the north. Volcanic activity started after a change in regional tectonics, which may have triggered the formation of magma chambers. The volcano developed in two phases, Ubinas I and Ubinas II: Ubinas I is represented by lava flows at

12549-428: The most recent volcanic stage has produced slightly different magmas, but overall the composition of Misti magmas is highly homogeneous. The composition of Misti magmas and these of its neighbours Pichu Pichu and Chachani resembles adakite , an unusual kind of volcanic rock formed by the direct melting of a subducting plate. Some rocks erupted by the volcano show evidence of hydrothermal alteration. The formation of

12690-411: The mountain. The water source for the mudflows is unclear, but the eruption took place during the neoglacial between 2,500 and 1,000 years ago. Thus Misti may have featured a snow or ice cap at the time of the eruption; its melting would have given rise to mudflows. Rainfall generated further mudflows after the eruption. The relative importance of pyroclastic flows and mudflows during the 2 ka eruption

12831-404: The nested summit craters. Tephra forms 5–6-metre (16–20 ft) thick deposits around the volcano, and pyroclastic surges reached distances of many kilometres more than 6,400 and 5,200 years ago. The 9,000 and 8,500 years old eruptions produced the "Sándwich" deposits. They extend for more than 15 kilometres (9.3 mi) on the southwestern flank of Misti, but they also resulted in ash fall over

12972-438: The nights. Fumarolic activity and degassing is limited to the crater; there is no evidence of such gas exhalations elsewhere on the volcano. Ubinas is a major source of volcanic carbon dioxide and sulfur dioxide in the atmosphere of Earth, producing SO 2 at a rate of about 11.4 ± 3.9 kilograms per second (1,510 ± 520 lb/min). The sulfur dioxide output changes with volcanic activity. Reportedly,

13113-463: The northern/western and southern/eastern foot of Misti, respectively. Inca roads from the Arequipa area passed by the volcano. There are numerous dams on the Rio Chili, including the Aguada Blanca Dam and reservoir north of the volcano, El Fraile, and Hidroeléctrica Charcani I, II, III, IV, V and VI. These dams have hydroelectric power plants which supply electricity to Arequipa. The river

13254-482: The northwest and Pichu Pichu to the southeast, and developed on top of a basement formed by numerous Miocene - Pliocene ignimbrites and volcano-derived debris. Numerous intense explosive eruptions took place during the last 50,000 years and covered the surrounding terrain with tephra . The last two significant eruptions were 2,000 years ago and in 1440–1470 AD ; since then, phases of increased fumarolic activity have sometimes been mistaken for eruptions. Misti

13395-406: The northwest flank of the volcano. The seismic activity appears to be linked to Misti's hydrothemal system. Seismic swarms were recorded in August 2012, May 2014 and June 2014. No deformation of the volcanic edifice is evident in satellite images. Clouds rising from the mountain are sometimes mistaken for renewed activity. Misti is Peru's most dangerous volcano and one of the most dangerous in

13536-699: The often thick crust . Volcanic activity in southern Peru goes back to the Jurassic . Various volcanic arcs formed in Peru during the past 30 million years: The Tacaza Arc 30–15 million years ago, the Lower Barroso 9–4 million years ago, the Upper Barroso 3–1 million years ago and the Pleistocene-Holocene Frontal Arc during the past one million years. Two distinct episodes of uplift took place 24–13 and 9–4 million years ago, and were accompanied by

13677-521: The oldest edifice. They have an age of 833,000 years, but it is not clear if they should be considered part of "Misti 1" or of a pre-Misti volcano. Sometimes, they are considered the first stage of Misti activity, with all the subsequent activity making up the second stage. After the south-southwestern collapse, the present stratovolcano began to grow 112,000 years ago. During the following 42,000 years lava flows and lava domes built an edifice with an elevation of 4,000–4,500 metres (13,100–14,800 ft), in

13818-542: The others are the dormant Chachani 15 kilometres (9.3 mi) northwest and extinct Pichu Pichu 20 kilometres (12 mi) southeast. This group lies at the margin of the Altiplano, next to the 600-square-kilometre (230 sq mi) tectonic depression of Arequipa where the city lies. The depression has dimensions of 30 by 15 kilometres (18.6 mi × 9.3 mi) and appears to be formed by fault activity. The terrain under Misti slopes south and this might make

13959-423: The plateau is about 2 kilometres (1.2 mi). The total volume of the mountain is estimated to be about 56 cubic kilometres (13 cu mi). The summit of the volcano is an elliptical caldera 1.4 kilometres (0.87 mi) wide and 150 metres (490 ft) deep, formed by collapses of the summit and explosive eruptions . The caldera walls are made of lava flows bearing traces of hydrothermal alteration;

14100-409: The ravines on the southern side and the Rio Chili gorge; the older volcanic structures lie mainly in the western sector of Misti. Only a few eruptions have been thoroughly investigated. Seismic tomography has identified solidified buried magma bodies from the early stages of volcanism. Long andesitic lava flows and ignimbrites, which reach a thickness of more than 400 metres (1,300 ft), form

14241-497: The region are considered to be part of a geothermal province known as "Ubinas" which also includes El Misti, and which deliver large amounts of dissolved minerals including arsenic to the local rivers. The climate of the area changes with elevation. The summit of Ubinas has a cold climate with temperatures frequently falling below 0 °C (32 °F); at lower elevations temperatures can exceed 18 °C (64 °F) during daytime, but night frosts are still possible. The region

14382-480: The region around the volcano, resulting in about US$ 1,000,000 of damage and the flight of local residents to Arequipa and Moquegua . The village of Querapi on the southern flank was temporarily evacuated to a location with shelters farther south, and two shelters were designated in low-risk areas around the volcano, one at Anascapa and the other at Chacchagen, 1.5 kilometres (0.93 mi) away from Matalaque. Furthermore, Lake Salinas , an important source of water in

14523-485: The region before about 45 million years ago when major uplift commenced. Ubinas, Ticsani and Huaynaputina form a group of volcanoes that extend in north-south direction north of the chain of volcanoes that make up the rest of the Central Volcanic Zone. These volcanoes have erupted rocks with similar geochemical traits and they are located around a graben occupied by the Rio Tambo; the marginal faults of this graben are

14664-413: The region, was threatened by the eruption. A new eruption period started on 2 September 2013 with a phreatic explosion , which was followed by more events in the next few days. Strong but variable seismic activity, the observation of thermal anomalies in satellite images and the exhalation of gases characterized this eruption period. Lava effusion began in the summit crater in 2014 and increased after

14805-409: The rhyolitic magmas erupted 34,000–31,000 years ago. Crystal-poor magma can form in the magmatic system through numerous processes and gives rise to the rhyolites and the volcanic plug. The existence of a third magma storage zone hosting mafic magmas at the base of the crust has been proposed. It is not clear whether Misti has a single magma chamber or multiple magma reservoirs at depth, although

14946-608: The rock composition implies that only one large magma system is present. The reservoir appears to be located at 6–15 kilometres (3.7–9.3 mi) depth and has a volume of several cubic kilometres. Every few millennia, a secondary rhyolitic reservoir forms at about 3 kilometres (1.9 mi) depth; it was last reactivated during the eruption 2 ka ago. The magma system is periodically recharged, but such an influx of new magma does not trigger eruptions; instead multiple recharges are necessary to cause activity. Numerous mixing and decompression events can happen to each magma batch before it

15087-578: The second forms a flat-topped terrain with an area of about 40 square kilometres (15 sq mi) on both sides of the Rio Chili. The perennial Rio Chili rounds the northern and western sides of Misti, where it has cut the 20-kilometre (12 mi) long and 150–2,600-metre (490–8,530 ft) deep Charcani Gorge. From southeast to southwest the Quebrada Carabaya, Quebrada Honda, Quebrada Grande, Quebrada Agua Salada, Quebrada Huarangual, Quebrada Chilca, Quebrada San Lazaro and Quebrada Pastores drain

15228-409: The sites of the volcanic vents and probably acted as magma conduits. The magmas erupted by all three volcanoes appear to originate in a common magma chamber at 20–35 kilometres (12–22 mi) depth, with seismic activity localized along the margins of the chamber. Aside from this deep reservoir, Ubinas also has a shallower magma chamber at 4–7 kilometres (2.5–4.3 mi) depth which appears to have

15369-702: The slopes of Ubinas are the Quebrada Infiernillo on the southeastern, Volcanmayo River on the southern and Quebrada Postcone on the southwestern flank. The Sacuaya River becomes the Ubinas River and after confluence with the Para ends in the Tambo River which eventually flows into the Pacific Ocean ; the Ubinas River valley is densely inhabited. Ubinas lies in the Salinas y Aguada Blanca National Reserve of Peru, which

15510-472: The sound of the fumaroles can be heard from the village of Ubinas. The fumaroles along with the spontaneous potential of Ubinas indicate that the volcano hosts an active hydrothermal system 1–3 kilometres (0.62–1.86 mi) below the caldera. About 41 springs occur in the area; of these two are hot springs , are found on the southeastern slopes of Ubinas and are known as Ubinas Termal and Ubinas Fria. Both lie at 3,267 metres (10,719 ft) elevation,

15651-433: The southeastern flank of the volcano. They emit noises, visible clouds of water vapour and the smell of hydrogen sulfide . The smell reaches the crater rim, and, at times, the gas becomes so concentrated that it causes irritations to the eyes, nose and throat. Fumarolic activity has been reported since the 1440–1470 eruption. In 1948–1949 and 1984–1985 it was intense enough to be seen from Arequipa. The fumarolic activity

15792-464: The southeastern flank reached a distance of 10 kilometres (6.2 mi) from the volcano, and left a collapse scar that is drained by the Volcanmayo River . This collapse took place early in the history of the volcano and removed a volume of about 2.8 cubic kilometres (0.67 cu mi) of rock from the mountain and underlying basement. Further collapses have occurred throughout the history of

15933-409: The southern and eastern sectors of present-day Misti. During the subsequent 20,000 years, repeated collapses of lava domes deposited blocks, fallout deposits and scoria on the southern side of Misti and on Chachani to the northwest. Traces of glacial erosion like cirques , evidence of hydromagmatic activity and mudflows imply that Misti was glaciated during the first last glacial maximum of

16074-615: The southern side of Misti. This activity brought "Misti 2" to an end; subsequently lava domes built "Misti 3" to an elevation of 5,600 metres (18,400 ft), almost entirely erasing the caldera. Between 36,000 and 20,000 years ago collapses of lava domes produced numerous block-and-ash flows of dacitic to andesitic composition, which reach thicknesses of several tens of metres on the southern side of Misti. The activity between 50,000 and 20,000 years ago has been christened "Cayma stage", and several eruption deposits from this time have been named: Eruptions 43,000 and 14,000 years ago dammed

16215-578: The stability and the hydrothermal system of Ubinas. Andesite and dacite are the dominant components of the volcano, though its rocks have compositions ranging from basaltic andesite to rhyolite . The volcanic rocks form a potassium -rich calc-alkaline suite. Phenocryst minerals vary between volcanic rocks of different composition and include amphibole , apatite , biotite , clinopyroxene , iron - titanium oxides , olivine , orthopyroxene , plagioclase and zircon . Assimilation of crustal material and fractional crystallization are involved in

16356-426: The steep slopes south of Misti would reach the suburbs of Arequipa and Chiguata. Most risk assessments are based on these two scenarios. The third scenario is a Plinian eruption like the "Fibroso" and "Sacaroso" events or the 1600 Huaynaputina eruption; pyroclastic flows would sweep all the flanks of Misti and past Arequipa, blocking the Rio Chili. Thick ash fall would occur over the entire region, including over

16497-403: The summit during the wet season , but does not persist; there are no glaciers . The upper slopes of the volcano are barren, while the lower slopes are covered by bushland . The volcano developed over four different stages. During each stage, lava flows and lava domes built up a mountain, whose summit then collapsed to form a caldera . The volcano is part of a volcano group with Chachani to

16638-580: The summit ranged from −6 °C (21 °F) in January to −9.7 °C (14.5 °F) in May, June and August but in 1968 temperatures at the summit rose above freezing for a few days per year. During most of the year, dry westerly winds blow over the Western Cordillera except during summer months, when convection over the Amazon forces easterly flow that draws moisture to the Cordillera. Most precipitation falls during

16779-418: The town of Ubinas was also considered. The 2006 and 2013–2017 activity induced the Peruvian government to invest additional resources in volcano monitoring. After these events, in 2015–2017 the volcano often persistently released ash and gas, accompanied by earthquakes as well as occasional explosions and eruption columns . In April 2015, for example, activity at Ubinas led to a declaration of emergency for

16920-423: The upper cone. Unlike neighbouring Chachani, Misti lacks any evidence of glacial or periglacial processes, probably due to its inner heat. There is no clear indication of past glaciation, either, except possibly on the western flank. A thin ice cover may not have left traces on the volcano, however. The present-day snowline lies above 5,800 metres (19,000 ft) elevation. Off the western coast of Peru,

17061-427: The upper sector of the volcano has a worn appearance. Glacial valleys such as the Ubinas and Para valleys, as well as cirques and moraines down to 4,000 metres (13,000 ft) and at the foot of the volcano, indicate that glaciers developed on Ubinas during the last glacial maximum . Other volcanic cones in the region all show heavy erosion by glaciation. The volcano rises 1.4 kilometres (0.87 mi) from

17202-465: The valleys that drain Ubinas in southeastern direction and landslides are hazardous for an area of the southern flank. The town closest to the volcano is only 4 kilometres (2.5 mi) away from Ubinas. Large Plinian eruptions could have effects on the city of Arequipa. The Volcano Observatory of INGEMMET monitors the seismic activity, any deformation and emissions of the mountain, and hot spring and gas composition at Ubinas. It regularly publishes

17343-447: The volcano and into the Holocene epoch, including one 1-cubic-kilometre (0.24 cu mi) collapse that left a hummocky deposit on the southern flank. The sloping terrain that Ubinas is built upon predisposes the mountain to south-directed landslides; future collapses in that direction are possible, with the heavily fractured southern flank of the caldera particularly at risk. In the 1970s, an ephemeral crater lake appeared in

17484-522: The volcano down; the mummies on Misti are the largest Inca sacrifice known. The name is either Quechua or Spanish and means "mixed", " mestizo " or "white"; it may refer to snow cover. The indigenous names are Putina ("mountain that growls" ) and in Aymara "Anukara" or Anuqara ("dog"); they both refer to the dog-like appearance of the volcano when viewed from the Altiplano . The original name of

17625-422: The volcano is also known as Ubinas I and the steeper upper part as Ubinas II; they represent different stages in the volcano's geological history. The most active volcano in Peru, Ubinas has a history of small to moderate explosive eruptions as well as a few larger eruptions, such as in 1667, along with persistent degassing and ash emissions . Activity at the volcano began in the Pleistocene epoch, and led to

17766-418: The volcano is cut by 20-to-80-metre (66 to 262 ft) deep ravines , while the northern side is flatter. Dune fields and volcanic ash deposits extend for 20 kilometres (12 mi) northeast of Misti; they are formed by wind-blown ash. The terrain between Arequipa and Misti is initially gently sloping, before reaching the steep flanks of the cone. There are no obvious traces of a sector collapse on

17907-450: The volcano was Putina; it only became known as "Misti" beginning in the 1780s. Other names for the volcano are Guagua-Putina, El Volcán ("the volcano"), San Francisco, and Volcán de Arequipa ("the Arequipa volcano"). Sometimes chroniclers confused it with other volcanoes like Ubinas and Huaynaputina . Settlement of the region began about 1,500 years ago. It is unclear whether the Inka were

18048-432: The volcano, except on its western foot and a narrow chute on the northwestern flank of Misti that reaches its summit. Two debris avalanche deposits lie on the southeastern and southwestern-southern side of Misti, extending 25 kilometres (16 mi) and 12 kilometres (7.5 mi) from the volcano. The first is made up by hummock-shaped hills of mixed debris and covers an area of 100 square kilometres (39 sq mi);

18189-506: The volcano. Reactivated volcanic activity started between 25,000 and 14,700 years ago and led to the emplacement of ash flows, pumice layers and tephra from phreatomagmatic and explosive eruptions, with deposits having thicknesses ranging from 2–4 metres (6 ft 7 in – 13 ft 1 in) in many places. The total volume of each eruption deposit ranges from 1–2 cubic kilometres (0.24–0.48 cu mi) and they crop out as far as 35 kilometres (22 mi) from Ubinas. It

18330-429: The volcano. Pyroclastic flows emanated from the column and descended the southern flanks of the volcano, possibly through the gap in the crater rim. During the course of the eruption, collapses of the crater and conduit walls caused a temporary decline in the intensity of the column. The eruption column periodically collapsed and reformed, until the eruption ended with phreatomagmatic explosions. Mudflows descended

18471-406: The volcano; a 2-kilometre (1.2 mi) wide caldera formed at an elevation of 5,400 metres (17,700 ft). More than ten eruptions took place during the last 11,000 years, with only brief pauses in activity. The activity between 21,000 and 2,000 years ago is known as the "Pacheco" stage. Holocene activity filled the younger caldera with scoria and lava flows, forming the "Misti 4" edifice with

18612-618: The volcanoes is formed by the partial melting of the mantle after fluids originating in the downgoing slab have altered the mantle; the magmas often undergo fractional crystallization and absorb crustal material. Southern Peru has been affected by volcanic activity since the Ordovician and the Permian - Jurassic period, subduction -related volcanism becoming important from the Cretaceous onwards. Beginning 91 million years ago, several volcanic arcs have been active in southern Peru: from

18753-421: The water would have infiltrated the edifice and evaporated from the volcanic heat. Comparisons between 1967 photos of the volcanic plug and more recent images show no changes. The volcano is seismically active, with long-period earthquakes, tremors, "tornillos" and volcano-tectonic earthquakes recorded. The hypocentres , the actual sites of the earthquakes, are found within the edifice of Misti and cluster on

18894-410: The waters flowing out of the springs have temperatures of 29.1 °C (84.4 °F) and 13.6 °C (56.5 °F), respectively. The composition of the waters in these springs indicate that they originate from the mixing of deep saline water, fresh water and volcanic fluids. Additional springs associated with the volcano are Baños de Cura, Exchaje, Huarina and Lucca; these hot springs and others in

19035-521: The western coast of South America, the Nazca Plate subducts beneath the South American Plate at a rate of 7–9 centimetres per year (2.8–3.5 in/year) in the Peru-Chile Trench . This subduction process is responsible for the formation of the Andes and the Altiplano - Puna plateau within the last 25 million years, as well as for volcanism and earthquakes . The magma erupted by

19176-461: The world, owing to its proximity (17 kilometres (11 mi)) to Arequipa, where more than a million inhabitants live. The city has expanded to within 12 kilometres (7.5 mi) of the volcano, with new towns like Alto Selva Alegre, Mariano Melgar, Miraflores and Paucarpata and towns such as Chiguata getting within 11 kilometres (6.8 mi). About 8.6% of Peru's GDP depends on Arequipa and would be impacted by future eruption of Misti. The city

19317-422: Was created to show and explain the procedures to follow in case of various eruption scenarios. Both maps were widely disseminated after publication to aid in the response to future eruptions. Fumaroles are active at the bottom of the inner crater, with about five separate fumarole areas identified within the crater before the 2006 eruption. In 1997, a gas cloud from the fumaroles filled the entire caldera during

19458-464: Was essentially unmonitored before the 2006 event: the inhabitants of the area were largely unaware of volcanic hazards, and there were no emergency plans for future eruptions available. A "Scientific Committee" was formed on March 30, 2006 to remedy these issues. A region of about 100 square kilometres (39 sq mi) was hit by the effects of the eruption. The ash fall from the eruption caused health problems and disrupted pastures and agriculture in

19599-462: Was founded in 1979. The town of Ubinas and the villages of Querapi , Tonohaya , Ubinas and Viscachani lie southeast, south, southeast and northwest of the volcano, respectively, and other villages in the area include Anascapa, Escacha, Huarina, Huatahua, Sacuaya, San Miguel and Tonohaya. In total about 5,000 people live within 12 kilometres (7.5 mi) from the volcano, with Querapi being only 4 kilometres (2.5 mi) away from Ubinas and thus

19740-578: Was probably a prolonged eruption that lasted for months or years, depositing ash in the Peruvian Laguna Salinas and possibly as far as Siple Dome and Law Dome in Antarctica. It is the oldest eruption of a South American volcano for which historical records exist. The eruption was severe enough that Mama Ana Huarque Coya, the wife of the Inka emperor Pachacutec , came to Chiguata, where black ash had fallen, to provide assistance. There

19881-581: Was the largest in historical time, producing about 0.1 cubic kilometres (0.024 cu mi) of scoria and reaching a volcanic explosivity index of 3. These eruptions have damaged communities around the volcano, and occasionally caused epidemics and human and cattle fatalities resulting from the ingestion of ash. Aside from regular eruptions, there are fumarolic -seismic events such as in 1995–1996 when sulfur dioxide and water vapour , emitted at temperatures of up to 440 °C (824 °F), formed clouds that rose over 1 kilometre (0.62 mi) above

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