116-802: Guallatiri is a volcano in Chile with an elevation of 6,060 to 6,071 m (19,882 to 19,918 ft). It is located southwest of the Nevados de Quimsachata volcanic group; some sources classify Guallatiri as a member. Guallatiri is a stratovolcano with numerous fumaroles around the summit. The summit may be a lava dome or volcanic plug , while the lower flanks of the volcano are covered by lava flows and lava domes. The volcano's eruptions have produced mostly dacite along with andesite and rhyolite . Past glaciation has left moraines on Guallatiri. A large eruption took place approximately 2,600 years ago. Guallatiri has been active in historical times with
232-459: A ghost town ) and Fourpeaked Mountain in Alaska, which, before its September 2006 eruption, had not erupted since before 8000 BCE. 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 a steep profile with
348-446: A hydrothermal system where intense rock-gas interaction takes place. The water originates in part from the magma and in part from precipitation. Different degrees of interaction with precipitation water may explain why the south-southwestern flank fumarole gases have a different composition than these released in the summit region. The fumarolic activity has produced intense hydrothermal alteration of Guallatiri's rocks east-northeast of
464-484: A magma chamber below the surface. The process that forms volcanoes is called volcanism . On Earth, volcanoes are most often found where tectonic plates are diverging or converging , and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a mid-ocean ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates whereas
580-506: A volcanic explosivity index of 2 took place in 1825 ± 25, 1913, July 1959, and December 1960. A further uncertain eruption took place in 1908 and additional poorly documented eruptions are reported from 1862, 1864, 1870, 1902, 1904, and 1987. Radiocarbon dating has yielded evidence of at least one eruption during the past 200 years. Increased steam emission was observed in December 1985 and initially attributed to Acotango volcano, before it
696-747: 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
812-479: 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
928-515: 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
1044-518: A flat surface. Pyroclastic flow deposits extend 10 km (6.2 mi) from Guallatiri. Radiocarbon dating has yielded ages ranging between 6,255 ± 41 and 140 ± 30 years Before Present . These flows are unrelated to the lava domes, which show no evidence of collapses that could have formed pyroclastic flows. Lahar deposits are found on the southern flanks of the volcano and do not exceed 2 m (6 ft 7 in) thickness. They form when volcanic material interacts with water, produced either by
1160-437: A graduated spectrum, with much overlap between categories, and does not always fit neatly into only one of these three separate categories. The USGS defines a volcano as "erupting" whenever the ejection of magma from any point on the volcano is visible, including visible magma still contained within the walls of the summit crater. While there is no international consensus among volcanologists on how to define an active volcano,
1276-453: A hummocky surface and resembles a pancake. There are both cold springs and hot springs on Guallatiri, indicating that groundwater interacts with the magmatic system. One hot spring is located at Chiriguaya on the northwestern foot of Guallatiri, where temperatures of 48 °C (118 °F) were measured in bubbling pools, and sinter deposition takes place. Several streams run off the mountain; they eventually enter Lake Chungará and
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#17328023668241392-426: A number of eruptions, the latest in 1960. Fumarolic and seismic activity is ongoing and has resulted in the deposition of sulfur and other minerals on the volcano. The volcano is covered by an ice cap above 5,500 to 5,800 m (18,000 to 19,000 ft) that has shrunk and fragmented during the course of the 20th and 21st centuries. Guallatiri, along with several other volcanoes, is part of Lauca National Park and
1508-443: A paper was published suggesting a new definition for the word 'volcano' that includes processes such as cryovolcanism . It suggested that a volcano be defined as 'an opening on a planet or moon's surface from which magma , as defined for that body, and/or magmatic gas is erupted.' This article mainly covers volcanoes on Earth. See § Volcanoes on other celestial bodies and cryovolcano for more information. The word volcano
1624-676: A refuge of the National Forest Corporation . Other nearby towns include Ancuta, Carbonire and Churiguaya. As of 2017 each had a population of less than 25 people. The provincial capital Putre is 55 km (34 mi) north of the volcano, and 130 km (81 mi) farther west, on the Pacific coast, is Arica . Economic activity in the area includes the Tambo Quemado border crossing , agriculture, animal husbandry, tourism and mountaineering, including ascents to
1740-769: 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
1856-461: 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 ,
1972-531: 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
2088-423: A two-stage growth of the volcano. Initially, the "Guallatiri I" stage grew in the form of andesitic and dacitic lava flows as well as heavily eroded pyroclastic deposits, which crop out around the volcano. Then the dacitic "Guallatiri II" developed in close proximity to the central vent; unlike the "Guallatiri I" units it has not been eroded by glaciation and flows still display flow structures. The central sector of
2204-632: A volcano is largely determined by the composition of the lava it erupts. The viscosity (how fluid the lava is) and the amount of dissolved gas are the most important characteristics of magma, and both are largely determined by the amount of silica in the magma. Magma rich in silica is much more viscous than silica-poor magma, and silica-rich magma also tends to contain more dissolved gases. Lava can be broadly classified into four different compositions: Mafic lava flows show two varieties of surface texture: ʻAʻa (pronounced [ˈʔaʔa] ) and pāhoehoe ( [paːˈho.eˈho.e] ), both Hawaiian words. ʻAʻa
2320-555: A volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit; however, this describes just one of the many types of volcano. The features of volcanoes are varied. The structure and behaviour of volcanoes depend on several factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have landscape features such as massive plateaus . Vents that issue volcanic material (including lava and ash ) and gases (mainly steam and magmatic gases) can develop anywhere on
2436-465: A volcano that has experienced one or more eruptions that produced over 1,000 cubic kilometres (240 cu mi) of volcanic deposits in a single explosive event. Such eruptions occur when a very large magma chamber full of gas-rich, silicic magma is emptied in a catastrophic caldera -forming eruption. Ash flow tuffs emplaced by such eruptions are the only volcanic product with volumes rivalling those of flood basalts . Supervolcano eruptions, while
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#17328023668242552-601: Is Lascar , which in 1993 produced the largest historical eruption of northern Chile. Guallatiri rises above Oligocene to Pliocene age volcanic and sedimentary rocks, which define the Lupica and Lauca Formations . The Lupica Formation is older and consists mainly of volcanic rocks, while the Lauca Formation is formed by volcanic and sedimentary rocks that were deposited within the basin and in part altered by glaciers. Archean to Precambrian - Paleozoic rocks make up
2668-441: Is 6,060 m (19,880 ft) or 6,071 m (19,918 ft) high; claims of even higher elevations appeared in past and some recent publications. It is a composite volcano or stratovolcano with a symmetric cone surmounted by a lava dome , lava complex or volcanic plug and a vent just south of it. Lava domes, lava flows, tephra and volcanic ash make up the mountain. Guallatiri rises about 1.7 km (1.1 mi) above
2784-739: Is a volcanic field of over 60 cinder cones. Based on satellite images, it has been suggested that cinder cones might occur on other terrestrial bodies in the Solar system too; on the surface of Mars and the Moon. Stratovolcanoes (composite volcanoes) are tall conical mountains composed of lava flows and tephra in alternate layers, the strata that gives rise to the name. They are also known as composite volcanoes because they are created from multiple structures during different kinds of eruptions. Classic examples include Mount Fuji in Japan, Mayon Volcano in
2900-531: 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
3016-412: Is characterized by a rough, clinkery surface and is the typical texture of cooler basalt lava flows. Pāhoehoe is characterized by its smooth and often ropey or wrinkly surface and is generally formed from more fluid lava flows. Pāhoehoe flows are sometimes observed to transition to ʻaʻa flows as they move away from the vent, but never the reverse. More silicic lava flows take the form of block lava, where
3132-569: Is considered to be easy to ascend (rated F on the French Climb grading by John Biggar) but toxic gases constitute a hazard in the summit region. The volcano lies in the Putre municipality , Arica y Parinacota Region . It is located south of Lake Chungará and 4 km (2.5 mi) west of Cerro Capurata . The latter is part of the Nevados de Quimsachata volcano chain which includes Umurata , Acotango and Capurata ; sometimes Guallatiri
3248-530: Is considered to be part of the Nevados de Quimsachata. The older Umurata and Acotango volcanoes are heavily eroded; Capurata is better preserved. Guallatiri is part of the larger Western Cordillera , the western boundary of the Altiplano high plateau . The small town of Guallatiri is 9.5 km (5.9 mi) southwest of the volcano and is the settlement closest to it; the town has a 17th-century church and
3364-565: Is derived from the name of Vulcano , a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan , the god of fire in Roman mythology . The study of volcanoes is called volcanology , sometimes spelled vulcanology . According to the theory of plate tectonics, Earth's lithosphere , its rigid outer shell, is broken into sixteen larger and several smaller plates. These are in slow motion, due to convection in
3480-584: Is expressed using the volcanic explosivity index (VEI), which ranges from 0 for Hawaiian-type eruptions to 8 for supervolcanic eruptions. As of December 2022 , the Smithsonian Institution 's Global Volcanism Program database of volcanic eruptions in the Holocene Epoch (the last 11,700 years) lists 9,901 confirmed eruptions from 859 volcanoes. The database also lists 1,113 uncertain eruptions and 168 discredited eruptions for
3596-628: Is monitored by the Chilean National Geology and Mining Service (SERNAGEOMIN). The term Guallatiri is derived from wallatiri , which means ' abundance of the Andean goose ' in Aymara , referring to the birds' frequent occurrence in the area. Other names are Punata (also an Aymara word), Huallatiri, Huallatire and Guallatire. It was first climbed in 1926 by the geologist Friedrich Ahlfeld [ de ] . The volcano
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3712-537: Is one of the several tuyas in the area of the Tuya River and Tuya Range in northern British Columbia. Tuya Butte was the first such landform analysed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near
3828-593: Is partially covered by moraines. Volcanic units are found both overlying and underlying glacial deposits such as moraines . Older volcanic rocks bear glacial striations , and volcanic bombs on the lower flanks may have been transported there by glaciers. Off the western coast of South America, the Nazca Plate subducts beneath the South American Plate at a rate of about 7–9 centimetres per year (2.8–3.5 inches per year). The subduction process
3944-671: Is responsible for the volcanism of the Northern Volcanic Zone , Central Volcanic Zone (CVZ) and Southern Volcanic Zone , and has also driven the formation of the Altiplano during the last 25 million years. The CVZ is a 1,500 km (930 mi) long chain of volcanoes spanning southern Peru, northern Chile, western Bolivia and northwestern Argentina. It contains about 58 active or potentially active volcanoes, 33 of which are located within Chile. The most active CVZ volcano
4060-503: Is the 30th most dangerous in the country. In 2013, the Southern Andean Volcano Observatory began to monitor Guallatiri by video, measurements of seismic activity and deformations of the volcanic structure. Volcano hazard maps have been published. Guallatiri was considered to be an apu or mallku , a protective mountain spirit. The mountain was and still is worshipped by local inhabitants, and
4176-451: 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
4292-450: 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
4408-471: Is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland , as well. Lava domes are built by slow eruptions of highly viscous lava. They are sometimes formed within the crater of a previous volcanic eruption, as in the case of Mount St. Helens , but can also form independently, as in
4524-519: Is unlike the global Last Glacial Maximum (LGM), which peaked between 21,000 and 19,000 years ago. This is a consequence of the climate in the region, where glacier extent was more sensitive to increased moisture supply than to decreasing temperatures; presumably the global LGM was too dry to allow glacier formation. Some glaciers were still present during the Holocene, evidenced by Holocene-age Domo Tinto lava dome which bears traces of glacial erosion and
4640-1014: 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
4756-403: 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
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4872-429: The Andean flamingo , Andean gull , Andean goose, buff-winged cinclodes , Chilean flamingo , condor , giant coot , James's flamingo , mountain parakeet , Puna ibis , Puna tinamou and torrent duck . Among the mammals are the alpaca , Altiplano chinchilla mouse , Andean swamp rat , lesser grison , llama , mountain degu , Osgood's leaf-eared mouse , short-tailed chinchilla and vicuña . Woodlands formed by
4988-617: The Cascade Volcanoes or the Japanese Archipelago , or the eastern islands of Indonesia . Hotspots are volcanic areas thought to be formed by mantle plumes , which are hypothesized to be columns of hot material rising from the core-mantle boundary. As with mid-ocean ridges, the rising mantle rock experiences decompression melting which generates large volumes of magma. Because tectonic plates move across mantle plumes, each volcano becomes inactive as it drifts off
5104-626: The Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide past one another. Large eruptions can affect atmospheric temperature as ash and droplets of sulfuric acid obscure the Sun and cool Earth's troposphere . Historically, large volcanic eruptions have been followed by volcanic winters which have caused catastrophic famines. Other planets besides Earth have volcanoes. For example, volcanoes are very numerous on Venus. Mars has significant volcanoes. In 2009,
5220-512: The Lauca River . Above 5,500 m (18,000 ft)–5,800 m (19,000 ft) elevation the volcano is covered with ice in the form of glaciers . As of 2017, an ice cap on Guallatiri covered an area of 0.796 km (0.307 sq mi) and had a volume of 0.026 km (0.0062 cu mi). Ice area has been retreating at a rate of 0.07 square kilometres per year (0.027 square miles per year) (between 1988 and 2017), leading to
5336-579: 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
5452-575: The basement . There is evidence that the terrain was tectonically active during the Quaternary . The composition of Guallatiri's rocks ranges from andesite over dacite to rhyolite , with dacites being predominant. The summit dome is formed by dacite and most outcrops are trachyandesite and trachydacite . The rocks define a potassium -rich calc-alkaline suite and contain amphibole , apatite , biotite , clinopyroxene , olivine and plagioclase phenocrysts , similar to other volcanoes in
5568-834: The landform and may give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Kīlauea in Hawaii. Volcanic craters are not always at the top of a mountain or hill and may be filled with lakes such as with Lake Taupō in New Zealand. Some volcanoes can be low-relief landform features, with the potential to be hard to recognize as such and be obscured by geological processes. Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter , Saturn , and Neptune ; and mud volcanoes , which are structures often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes except when
5684-891: 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
5800-443: 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
5916-523: The oral tradition of Chipaya , cold winds called soqo blow from the Pacific Ocean to the Altiplano and towards Guallatiri. The volcano there is linked with Hell . The Chipaya believed that the waters of the Lauca River originate on Guallatiri and come directly from hell. Volcano A volcano is a rupture in the crust of a planetary-mass object , such as Earth , that allows hot lava , volcanic ash , and gases to escape from
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#17328023668246032-616: 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
6148-485: 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
6264-527: The 1993 eruption of Lascar may have occurred at Guallatiri. The largest Holocene event at the volcano was a Plinian or sub-Plinian eruption that deposited tephra and pumice southwest of the volcano, reaching thicknesses of 1.3 m (4 ft 3 in) at 12 km (7.5 mi) distance, approximately 2,600 years ago. Non-explosive eruptions also took place, such as the Domo Tinto eruption 5,000 ± 3,000 years ago. The eruption emplaced lobes of lava over
6380-585: 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
6496-895: The Atlantic Ocean and the Amazon , especially during cold events of the El Niño–Southern Oscillation when moisture supply increases. Tree ring chronologies from Polylepis tarapacana trees growing at Guallatiri have been used for climate reconstructions. Volcanic activity at Guallatiri commenced either about 710,000 or 262,000–130,000 years ago and the volcano subsequently grew during the Pleistocene and Holocene . Total magma supply at Guallatiri amounts to 0.19–0.36 cubic kilometres per millennium (0.046–0.086 cubic miles per millennium), less than at Parinacota but greater than at Lascar. Jorquera et al. in 2019 described
6612-816: The Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift , the Wells Gray-Clearwater volcanic field , and the Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary , 3,000 kilometres (1,900 mi) deep within Earth. This results in hotspot volcanism , of which
6728-622: The Philippines, and Mount Vesuvius and Stromboli in Italy. Ash produced by the explosive eruption of stratovolcanoes has historically posed the greatest volcanic hazard to civilizations. The lavas of stratovolcanoes are higher in silica, and therefore much more viscous, than lavas from shield volcanoes. High-silica lavas also tend to contain more dissolved gas. The combination is deadly, promoting explosive eruptions that produce great quantities of ash, as well as pyroclastic surges like
6844-613: The USGS defines a volcano as active whenever subterranean indicators, such as earthquake swarms , ground inflation, or unusually high levels of carbon dioxide or sulfur dioxide are present. The USGS defines a dormant volcano as any volcano that is not showing any signs of unrest such as earthquake swarms, ground swelling, or excessive noxious gas emissions, but which shows signs that it could yet become active again. Many dormant volcanoes have not erupted for thousands of years, but have still shown signs that they may be likely to erupt again in
6960-819: 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
7076-748: 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
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#17328023668247192-510: The boundary with the Yukon Territory . Mud volcanoes (mud domes) are formations created by geo-excreted liquids and gases, although several processes may cause such activity. The largest structures are 10 kilometres in diameter and reach 700 meters high. The material that is expelled in a volcanic eruption can be classified into three types: The concentrations of different volcanic gases can vary considerably from one volcano to
7308-515: The breakup of the ice cap into several separate ice bodies. According to a 2005 study by Rivera et al. , heat emitted by fumaroles may have contributed to the enhanced melting of the ice. Glacial deposits on Guallatiri cover an area of about 80 km (31 sq mi) above 4,650 m (15,260 ft) elevation, with lateral moraines reaching lengths of 2 km (1.2 mi) and thicknesses of 15 m (49 ft). Glaciers reached their maximum extent between 13,500 and 8,900 years ago. This
7424-402: The case of Lassen Peak . Like stratovolcanoes, they can produce violent, explosive eruptions, but the lava generally does not flow far from the originating vent. Cryptodomes are formed when viscous lava is forced upward causing the surface to bulge. The 1980 eruption of Mount St. Helens was an example; lava beneath the surface of the mountain created an upward bulge, which later collapsed down
7540-469: The church in the town of Guallatiri is constructed so that it points to the volcano. In the past, the Aymara community of Guallatire used to celebrate rituals at the foothills of the volcano every January 1. They regarded Guallatiri, which they called Qapurata, to be a family consisting of a wife (the eastern María Qapurata), a husband (the western Pedro Qapurata) and a daughter (the middle Elena Qapurata). In
7656-743: The enormous area they cover, and subsequent concealment under vegetation and glacial deposits, supervolcanoes can be difficult to identify in the geologic record without careful geologic mapping . Known examples include Yellowstone Caldera in Yellowstone National Park and Valles Caldera in New Mexico (both western United States); Lake Taupō in New Zealand; Lake Toba in Sumatra , Indonesia; and Ngorongoro Crater in Tanzania. Volcanoes that, though large, are not large enough to be called supervolcanoes, may also form calderas in
7772-706: The first Panamerican Congress on Mine Engineering and Geology, in 1942 the volcano had about 800,000 metric tons (790,000 long tons; 880,000 short tons) of sulfur ore with a grade of about 55% sulfur. The volcano may be an important cause of arsenic pollution in the region. The volcano is inside the Lauca National Park and the wetlands ( Spanish : Bofedales ) in the area of Guallatiri have regional importance. Vegetation there include Arenaria rivularis , Calandrinia compacta , Deyeuxia curvula , Distichlis humilis , Lobelia oligophylla and Oxychloe andina . Animal species include birds such as
7888-540: 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
8004-431: The flow is covered with angular, vesicle-poor blocks. Rhyolitic flows typically consist largely of obsidian . Tephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases. Magma commonly explodes as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface . These violent explosions produce particles of material that can then fly from
8120-610: The formation of a submarine volcano off the coast of Mayotte . Subglacial volcanoes develop underneath ice caps . They are made up of lava plateaus capping extensive pillow lavas and palagonite . These volcanoes are also called table mountains, tuyas , or (in Iceland) mobergs. Very good examples of this type of volcano can be seen in Iceland and in British Columbia . The origin of the term comes from Tuya Butte , which
8236-448: The fumaroles are sulfates such as baryte and sulfides , including cinnabar , antimony sulfides and arsenic sulfides. The temperatures of the fumaroles range between 83.2–265 °C (181.8–509.0 °F). Guallatiri produces gases consisting of carbon dioxide and water vapour , with hydrogen chloride , hydrogen fluoride , hydrogen sulfide , methane and sulfur dioxide as additional components. They appear to originate from
8352-420: The fumaroles. According to a report by mountaineers in 1966, fire emanated from the fumarole vents. Future eruptions may consist of the emission of lava domes or lava flows, preceded by explosive activity that could impact the settlements of Ancuta and Guallatiri on the southern and western flanks. Large explosive eruptions could deposit pyroclastics over hundreds of kilometres, with the direction depending on
8468-585: The future. In an article justifying the re-classification of Alaska's Mount Edgecumbe volcano from "dormant" to "active", volcanologists at the Alaska Volcano Observatory pointed out that the term "dormant" in reference to volcanoes has been deprecated over the past few decades and that "[t]he term "dormant volcano" is so little used and undefined in modern volcanology that the Encyclopedia of Volcanoes (2000) does not contain it in
8584-466: The glossaries or index", however the USGS still widely employs the term. Previously a volcano was often considered to be extinct if there were no written records of its activity. Such a generalization is inconsistent with observation and deeper study, as has occurred recently with the unexpected eruption of the Chaitén volcano in 2008. Modern volcanic activity monitoring techniques, and improvements in
8700-478: 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
8816-458: 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
8932-492: The interior of a continent and lead to rifting. Early stages of rifting are characterized by flood basalts and may progress to the point where a tectonic plate is completely split. A divergent plate boundary then develops between the two halves of the split plate. However, rifting often fails to completely split the continental lithosphere (such as in an aulacogen ), and failed rifts are characterized by volcanoes that erupt unusual alkali lava or carbonatites . Examples include
9048-452: 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
9164-421: The melting of ice or through intense rainfall. Traces of Holocene-age lahars from Guallatiri have been found in river valleys. Guallatiri is the second-most active volcano (after Lascar ) in northern Chile. Since the 19th century, numerous small explosive eruptions have produced thin tephra layers. The eruption history of Guallatiri is little known and historical eruptions are poorly documented. Eruptions with
9280-419: The mid-oceanic ridge is above sea level, volcanic islands are formed, such as Iceland . Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. The oceanic plate subducts (dives beneath the continental plate), forming a deep ocean trench just offshore. In a process called flux melting , water released from the subducting plate lowers the melting temperature of
9396-551: The modelling of the factors that produce eruptions, have helped the understanding of why volcanoes may remain dormant for a long time, and then become unexpectedly active again. The potential for eruptions, and their style, depend mainly upon the state of the magma storage system under the volcano, the eruption trigger mechanism and its timescale. For example, the Yellowstone volcano has a repose/recharge period of around 700,000 years, and Toba of around 380,000 years. Vesuvius
9512-415: The most dangerous type, are very rare; four are known from the last million years , and about 60 historical VEI 8 eruptions have been identified in the geologic record over millions of years. A supervolcano can produce devastation on a continental scale, and severely cool global temperatures for many years after the eruption due to the huge volumes of sulfur and ash released into the atmosphere. Because of
9628-438: The mud volcano is actually a vent of an igneous volcano. Volcanic fissure vents are flat, linear fractures through which lava emerges. Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent. They generally do not explode catastrophically but are characterized by relatively gentle effusive eruptions . Since low-viscosity magma
9744-452: The next. Water vapour is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide . Other principal volcanic gases include hydrogen sulfide , hydrogen chloride , and hydrogen fluoride . A large number of minor and trace gases are also found in volcanic emissions, for example hydrogen , carbon monoxide , halocarbons , organic compounds, and volatile metal chlorides. The form and style of an eruption of
9860-876: The north side of the mountain. Cinder cones result from eruptions of mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 metres (100 to 1,300 ft) high. Most cinder cones erupt only once and some may be found in monogenetic volcanic fields that may include other features that form when magma comes into contact with water such as maar explosion craters and tuff rings . Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones. In New Mexico , Caja del Rio
9976-549: The ocean surface as new islands or floating pumice rafts . In May and June 2018, a multitude of seismic signals were detected by earthquake monitoring agencies all over the world. They took the form of unusual humming sounds, and some of the signals detected in November of that year had a duration of up to 20 minutes. An oceanographic research campaign in May 2019 showed that the previously mysterious humming noises were caused by
10092-420: The ocean surface, due to the rapid cooling effect and increased buoyancy in water (as compared to air), which often causes volcanic vents to form steep pillars on the ocean floor. Hydrothermal vents are common near these volcanoes, and some support peculiar ecosystems based on chemotrophs feeding on dissolved minerals. Over time, the formations created by submarine volcanoes may become so large that they break
10208-471: The ocean's surface. In the deep ocean basins, the tremendous weight of the water prevents the explosive release of steam and gases; however, submarine eruptions can be detected by hydrophones and by the discoloration of water because of volcanic gases . Pillow lava is a common eruptive product of submarine volcanoes and is characterized by thick sequences of discontinuous pillow-shaped masses which form underwater. Even large submarine eruptions may not disturb
10324-468: The one that destroyed the city of Saint-Pierre in Martinique in 1902. They are also steeper than shield volcanoes, with slopes of 30–35° compared to slopes of generally 5–10°, and their loose tephra are material for dangerous lahars . Large pieces of tephra are called volcanic bombs . Big bombs can measure more than 1.2 metres (4 ft) across and weigh several tons. A supervolcano is defined as
10440-425: The overlying mantle wedge, thus creating magma . This magma tends to be extremely viscous because of its high silica content, so it often does not reach the surface but cools and solidifies at depth . When it does reach the surface, however, a volcano is formed. Thus subduction zones are bordered by chains of volcanoes called volcanic arcs . Typical examples are the volcanoes in the Pacific Ring of Fire , such as
10556-619: The plume, and new volcanoes are created where the plate advances over the plume. The Hawaiian Islands are thought to have been formed in such a manner, as has the Snake River Plain , with the Yellowstone Caldera being part of the North American plate currently above the Yellowstone hotspot . However, the mantle plume hypothesis has been questioned. Sustained upwelling of hot mantle rock can develop under
10672-760: The region. A single lava bomb made out of obsidian has been found. Mafic rock enclaves have been observed in Domo Tinto rocks, which indicate that mafic magmas were injected into the magma chamber and mixed with already present magma. Fractional crystallization and magma mixing processes gave rise to Guallatiri's magmas. Fumaroles have deposited minerals such as anhydrite , baryte , cristobalite , gypsum , quartz , sassolite and sulfur . Less common are galena , orpiment and pyrite . Sulfur deposits have yellow, orange or red colours and are sometimes accompanied by arsenic -sulfur compounds that also contain iodine , mercury , selenium and tellurium . Sulfur deposits occur on Guallatiri's southern flank; according to
10788-435: The same time interval. Volcanoes vary greatly in their level of activity, with individual volcanic systems having an eruption recurrence ranging from several times a year to once in tens of thousands of years. Volcanoes are informally described as erupting , active , dormant , or extinct , but the definitions of these terms are not entirely uniform among volcanologists. The level of activity of most volcanoes falls upon
10904-492: The same way; they are often described as "caldera volcanoes". Submarine volcanoes are common features of the ocean floor. Volcanic activity during the Holocene Epoch has been documented at only 119 submarine volcanoes, but there may be more than one million geologically young submarine volcanoes on the ocean floor. In shallow water, active volcanoes disclose their presence by blasting steam and rocky debris high above
11020-464: 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
11136-622: The solidified erupted material that makes up the mantle of a volcano may be stripped away that its inner anatomy becomes apparent. Using the metaphor of biological anatomy , such a process is called "dissection". Cinder Hill , a feature of Mount Bird on Ross Island , Antarctica , is a prominent example of a dissected volcano. Volcanoes that were, on a geological timescale, recently active, such as for example Mount Kaimon in southern Kyūshū , Japan , tend to be undissected. Eruption styles are broadly divided into magmatic, phreatomagmatic, and phreatic eruptions. The intensity of explosive volcanism
11252-419: The southern and southwestern flanks. Tephra deposits are mainly located on the eastern and southern side of Guallatiri. Tuffs and pyroclastic flow deposits occur both in the summit region and in radial valleys that emanate from Guallatiri, although some of the deposits southwest of the volcano have been reinterpreted as being reworked sediments. Apart from volcanic rocks, glacial deposits cover large parts of
11368-422: The southern area. Some sources also identify a third area on the upper western flank. The vents of individual fumaroles sometimes form 6 m (20 ft) wide and 3 m (10 ft) high cones, and there are small explosion craters reaching widths of 5 m (16 ft) in the summit region. Pahoehoe -like flows up to 15 m (50 ft) long have been formed by liquid sulfur . Other minerals deposited by
11484-488: The summit and at a lower elevation northwest of it. Fumarole clouds, derived mainly from the summit fumarole, are visible for more than 200 km (125 mi) and from infrared satellite images. The fumarole cloud influences the perception of volcanic activity by the local population. Puffing behaviour was noted in 1996 and emissions every half-hour in November 1987, which gave rise to yellow-white plumes up to 1 km (0.62 mi) high. Jet-like noises are heard from
11600-407: The summit of Guallatiri. There are no known archeological sites on the summit of Guallatiri, unlike several other mountains in the region. Possible reasons are the continuous ice cover and the constant volcanic activity. The frontier between Bolivia and Chile runs along the Nevados de Quimsachata northeast of Guallatiri, not far from the volcano. The volcano is remote and thus poorly known. Guallatiri
11716-406: The surrounding areas, and initially not seismically monitored before its unanticipated and catastrophic eruption of 1991. Two other examples of volcanoes that were once thought to be extinct, before springing back into eruptive activity were the long-dormant Soufrière Hills volcano on the island of Montserrat , thought to be extinct until activity resumed in 1995 (turning its capital Plymouth into
11832-570: The surrounding terrain and covers an area of about 85 km (33 sq mi); the total volume is about 50 cubic kilometres (12 cubic miles). Thick lava flows emanate in all directions but are primarily noted on the northern and western flanks. The flows reach thicknesses of 230 m (750 ft) and lengths of 8 km (5 mi). The lava flows have a lobate appearance even when they are heavily eroded, and display levees , ogives , polygonal cracks and blocky surfaces. Older flows have been eroded into hills. Block-and-ash flows form fans on
11948-434: The theory of plate tectonics. For example, some volcanoes are polygenetic with more than one period of activity during their history; other volcanoes that become extinct after erupting exactly once are monogenetic (meaning "one life") and such volcanoes are often grouped together in a geographical region. At the mid-ocean ridges , two tectonic plates diverge from one another as hot mantle rock creeps upwards beneath
12064-444: The thinned oceanic crust . The decrease of pressure in the rising mantle rock leads to adiabatic expansion and the partial melting of the rock, causing volcanism and creating new oceanic crust. Most divergent plate boundaries are at the bottom of the oceans, and so most volcanic activity on Earth is submarine, forming new seafloor . Black smokers (also known as deep sea vents) are evidence of this kind of volcanic activity. Where
12180-436: The tree Polylepis tarapacana occur on Guallatiri; this tree forms the world's highest woodlands. The upper parts of the mountain are covered with rocks and pioneer vegetation to about 5,500 m (18,000 ft) elevation. The region has a tundra climate . Most precipitation falls during the summer months, amounting to about 236 mm (9.3 in) per year, averaged between 1997 and 2017. Moisture mainly originates in
12296-431: The underlying ductile mantle , and most volcanic activity on Earth takes place along plate boundaries, where plates are converging (and lithosphere is being destroyed) or are diverging (and new lithosphere is being created). During the development of geological theory, certain concepts that allowed the grouping of volcanoes in time, place, structure and composition have developed that ultimately have had to be explained in
12412-483: The volcano is mainly of Holocene age while the peripheral parts date to the Pleistocene. In 2021, Sepúlveda et al. envisaged six separate stages, rocks from the first four crop out mainly at the periphery of the volcano and the last two in its central sector. All these units were erupted by the central vent of Guallatiri. Some lava flows are well preserved, while others have been glaciated. Large eruptions similar to
12528-548: The volcano may threaten towns in Bolivia and ash clouds from Guallatiri could impact airports in the wider region as far as Paraguay and Argentina . The vulnerability of the local population reflects both widespread poverty and marginalization, and the low population density. Significant eruptions are expected to reoccur on century timescales. Guallatiri is in the second category in the Chilean scale of dangerous volcanoes and
12644-418: The volcano, and there are traces of mass failures . On the southern flank, there are two lava domes named Domo Tinto and Domo Sur; other than these Guallatiri has no lateral vents. Domo Tinto is 100 m (330 ft) wide and 100 m (330 ft) high while Domo Sur (1.5 km (0.93 mi) southwest of Domo Tinto) is 120 m (390 ft) thick and 750 m (2,460 ft) wide. Domo Tinto has
12760-492: The volcano. Solid particles smaller than 2 mm in diameter ( sand-sized or smaller) are called volcanic ash. Tephra and other volcaniclastics (shattered volcanic material) make up more of the volume of many volcanoes than do lava flows. Volcaniclastics may have contributed as much as a third of all sedimentation in the geologic record. The production of large volumes of tephra is characteristic of explosive volcanism. Through natural processes, mainly erosion , so much of
12876-424: The volcanoes of the East African Rift . A volcano needs a reservoir of molten magma (e.g. a magma chamber), a conduit to allow magma to rise through the crust, and a vent to allow the magma to escape above the surface as lava. The erupted volcanic material (lava and tephra) that is deposited around the vent is known as a volcanic edifice , typically a volcanic cone or mountain. The most common perception of
12992-405: The wind at the time of the eruption. Lahars would mainly impact the western and southwestern sectors of the volcano, as the snow cover is concentrated there. Lava flows would also primarily impact this sector of the volcano. Pyroclastic flows may impact areas within 12 km (7.5 mi) of Guallatiri, including the settlements Ancuta and Guallatiri. Apart from Ancuta and Guallatiri in Chile,
13108-412: 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
13224-421: Was described by Roman writers as having been covered with gardens and vineyards before its unexpected eruption of 79 CE , which destroyed the towns of Herculaneum and Pompeii . Accordingly, it can sometimes be difficult to distinguish between an extinct volcano and a dormant (inactive) one. Long volcano dormancy is known to decrease awareness. Pinatubo was an inconspicuous volcano, unknown to most people in
13340-449: Was induced by the 2001 Peru earthquake . Satellite imaging has not shown any evidence of ongoing deformation of the volcanic structure. Guallatiri features fumaroles and solfataras , and mud pools have also been reported. There are two main areas, one on the western flank 50 m (160 ft) below the summit and another on the south-southwestern flank. Fumaroles form alignments, and a 400 m (1,300 ft) long fracture lies in
13456-488: Was linked to Guallatiri; it may have been an eruption of the latter. In May 2015, the Chilean National Geology and Mining Service (SERNAGEOMIN) raised the volcano alert level when seismic activity increased and a 200 m (660 ft) high plume appeared over the volcano, only to lower it again in July when activity decreased. Shallow earthquakes and sporadic seismic swarms have been recorded at Guallatiri; one such swarm
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