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111-517: Uturuncu is a dormant volcano in the Sur Lípez Province of Bolivia. It is 6,008 metres (19,711 ft) high, has two summit peaks, and consists of a complex of lava domes and lava flows with a total volume estimated to be 50–85 km . It bears traces of a former glaciation , even though it does not currently carry glaciers. Volcanic activity took place during the Pleistocene epoch and

222-450: A ghost town ) and Fourpeaked Mountain in Alaska, which, before its September 2006 eruption, had not erupted since before 8000 BCE. Pyroclastic flow Pyroclastic flows are the most deadly of all volcanic hazards and are produced as a result of certain explosive eruptions ; they normally touch the ground and hurtle downhill or spread laterally under gravity. Their speed depends upon

333-842: A mid-ocean ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates whereas 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

444-518: A French island in the Caribbean. Pyroclastic flows that contain a much higher proportion of gas to rock are known as "fully dilute pyroclastic density currents" or pyroclastic surges . The lower density sometimes allows them to flow over higher topographic features or water such as ridges, hills, rivers, and seas. They may also contain steam, water, and rock at less than 250 °C (480 °F); these are called "cold" compared with other flows, although

555-465: A consequence of the deformation, as intruding magma pressurizes and destabilizes local faults , as well as the ascent of fluids in faults and cracks. Further triggering processes are large earthquakes such as the 2010 Maule earthquake , which caused an intense seismic swarm in February 2010. Magnetotelluric imaging of the volcano has found a number of high-conductivity anomalies below Uturuncu, including

666-523: A consequence of the upward movement of fluids, rather than magmatic processes. It has been described as an ascending diapir , a plate-shaped intrusion or as a growing pluton although an alternative theory holds the ascent of volatiles along a magma column reaching to the Altiplano–Puna magmatic body as responsible for the surface deformation; in that case the uplift might reverse over time. Such surface uplift has been observed at other volcanic centres in

777-445: A former glacier originating both from the summit and from an area about 0.5 kilometres (0.31 mi) south of the summit. This only weakly erosive glacier deposited five sets of moraines up to 5 metres (16 ft) high within the shallow valley; the lowest of these lies at 4,800–4,850 metres (15,750–15,910 ft) elevation and appears to be a product of an early last glacial maximum between 65,000 and 37,000 years ago, earlier than

888-437: 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,

999-508: A high elevation region, such as the potentially active volcanoes Irruputuncu , Olca-Paruma , Aucanquilcha , Ollagüe , Azufre , San Pedro , Putana , Sairecabur , Licancabur , Guayaques , Colachi and Acamarachi . Uturuncu has formed about 100 kilometres (62 mi) east of the main volcanic front in the Western Cordillera , in a terrain formed by various volcanic and sedimentary rocks of Miocene to Quaternary age. The region

1110-400: A hydrothermal system when brines drained out underground. This area may have begun subsiding in 2014. Deformation stopped in 2017. The deformation is most likely caused by magma intruding into the crust from the Altiplano–Puna magmatic body, with the intrusion taking place at a level below that where magma accumulated prior to past eruptions of Uturuncu. The more recent changes may instead be

1221-429: A number of calderas, composite volcanoes and about 10 000  km of ignimbrite. Uturuncu lies at its centre but unlike it most surrounding volcanic systems have been characterized by explosive eruptions, including several so-called " supereruptions " with Volcanic Explosivity Indexes of 8 at Cerro Guacha, La Pacana , Pastos Grandes and Vilama. Over 50   volcanoes in the region are potentially active. Within

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1332-443: 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

1443-425: A pyroclastic flow traveled for several hundreds of meters above the sea. A pyroclastic flow can interact with a body of water to form a large amount of mud, which can then continue to flow downhill as a lahar . This is one of several mechanisms that can create a lahar. In 1963, NASA astronomer Winifred Cameron proposed that the lunar equivalent of terrestrial pyroclastic flows may have formed sinuous rilles on

1554-500: A reconnaissance mission carried out by scientists in 2003, and numerous geophysical studies have been carried out on the volcano. The volcano has been used to reconstruct the regional history of glaciation . The term uturuncu means ' jaguar ' in the Quechua language . The volcano is visible from afar. Today Uturuncu is a tourism target. It was first ascended in 1955 by Friedrich Adolf Ernest Ahlfeld (Germany), but like other volcanoes in

1665-641: A relatively flat descent of the Nazca Plate until 12 mya ago, after which it steepened. The Altiplano–Puna volcanic complex formed beginning 10 mya ago, with a volcanic flare-up occurring during the Miocene. The complex covers an area between 50,000 square kilometres (19,000 sq mi) and 70,000 square kilometres (27,000 sq mi) of the Altiplano- Puna in Argentina , Bolivia and Chile and consists of

1776-438: A research team at Kiel University , Germany, of pyroclastic flows moving over the water. When the reconstructed pyroclastic flow (stream of mostly hot ash with varying densities) hit the water, two things happened: the heavier material fell into the water, precipitating out from the pyroclastic flow and into the liquid; the temperature of the ash caused the water to evaporate, propelling the pyroclastic flow (now only consisting of

1887-502: A ring could constitute a future pathway for magma transport or the margin of a future caldera. Whether the ongoing unrest at Uturuncu is part of a benign process of the growth of a pluton or the prelude of a new eruption or even a caldera-forming eruption is as of 2008 an open question. A large caldera-forming eruption could have catastrophic, globe-spanning consequences as demonstrated by the 1815 eruption of Mount Tambora in Indonesia and

1998-405: A short-term rate. The deformation is centered on an area 5 kilometres (3.1 mi) west of the summit and is most likely of magmatic origin given the lack of a large hydrothermal system at the volcano and the depth of the deformation. The form of the deforming structure is not well known but it lies presumably at a depth of 15–20 kilometres (9.3–12.4 mi) below sea level. The uplifting area

2109-440: A temporary deformation of the volcano that eventually deflates over time, or the current uplift might only be in its beginning stage. The term 'zombie volcano' has been coined to describe volcanoes like Uturuncu that have been inactive for a long time but are actively deforming. In addition, the volcano features persistent seismic activity with occasional bursts of higher activity; about three or four earthquakes occur every day at

2220-429: A tooth-shaped anomaly that begins at 2 kilometres (1.2 mi) depth and continues to over 80 kilometres (50 mi) of depth. Such structures have been found at other volcanoes and explained by the presence of magma. Seismic activity concentrates at the top of this anomaly. Finally, tectonic stress patterns delineate a 40–80 kilometres (25–50 mi) wide ring surrounding the volcano that may be prone to fracturing; such

2331-632: 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

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2442-555: 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

2553-465: 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

2664-430: A weak hydrothermal system is likely at Uturuncu although probably at great depth, considering the low temperature and spread out nature of the fumarolic activity. There may be a shallow magma chamber below the volcano at 1–3 kilometres (0.62–1.86 mi) below sea level. Interferometric synthetic-aperture radar imaging has discovered that a region of about 1,000 square kilometres (390 sq mi) around Uturuncu

2775-513: A wet and cold climate associated with Heinrich event 1 . At this same time 17,000–13,000   years ago, shorelines formed around the lakes that surround Uturuncu; Lake Tauca may have been a source of moisture for Uturuncu. After 14,000 years ago, the glacier receded at the same time as climate warmed during the Bølling–Allerød warming and the region became drier. There is little information on local climatology, but mean annual precipitation

2886-415: A wide magmatic sill where rocks are partially molten, the Altiplano–Puna magmatic body. Its existence has been established with various techniques; it extends over an area of 50,000 square kilometres (19,000 sq mi) and has a volume of about 500 000  km with a thickness variously estimated at 1–20 kilometres (0.62–12.43 mi); about 20-30% of its volume is melt. It has been referred to as

2997-573: A wide, deep conductor that extends to the volcanic arc to the west and several shallower ones which ascend from the deep conductor that appears to coincide with the Altiplano–Puna magmatic body. The shallow conductors appear to relate to local volcanoes such as the Laguna Colorada vent but also Uturuncu; the latter conductor lies at 2–6 kilometres (1.2–3.7 mi) depth, is less than 10 kilometres (6.2 mi) wide and may consist of molten rock with saline aqueous fluids. Seismic tomography has found

3108-727: 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

3219-445: 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 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,

3330-465: Is about 100–200 millimetres per year (3.9–7.9 in/year) or even less than that, most of it originating in the Amazon basin to the east and falling during December, January and February. This low amount of precipitation is not adequate to sustain glaciers even though the summit of Uturuncu lies above the freezing level , but it is enough to generate a seasonal snowcap on the mountain. Annual temperatures in

3441-472: Is bordered by steep slopes; Laguna Celeste is located northeast of Uturuncu, Chojllas southeast of the volcano and Loromayu to the south. The first two receive their inflow from Uturuncu. Beach terraces , deposits of diatomaceous earth and former shorelines are visible around the lakes. The Rio Grande de Lípez flows along the western foot of the volcano and receives tributaries which originate close to Uturuncu's northeastern foot; it eventually flows into

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3552-412: 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

3663-512: Is characterized by the Altiplano high plateau , which reaches an elevation of 4,000 metres (13,000 ft) and is only exceeded by Tibet in dimension. The Vilama (8.41 mya old) and Guacha (5.65 mya old) ignimbrites underlie the volcano and crop out in the Quetena River valley. The Vilama lavas (4 mya old) are found southwest of Uturuncu and are partly buried by the volcano. The crust in

3774-554: 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

3885-567: 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

3996-524: 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

4107-548: Is sometimes abbreviated to PDC (pyroclastic density current). Several mechanisms can produce a pyroclastic flow: Flow volumes range from a few hundred cubic meters to more than 1,000 cubic kilometres (240 cu mi). Larger flows can travel for hundreds of kilometres, although none on that scale has occurred for several hundred thousand years. Most pyroclastic flows are around one to ten cubic kilometres ( 1 ⁄ 4 – 2 + 1 ⁄ 2  cu mi) and travel for several kilometres. Flows usually consist of two parts:

4218-517: Is surrounded by a ring-shaped area of subsidence (sinking), which is occurring at a rate of 2 millimetres per year (0.079 in/year); the total width of deforming terrain is about 170 kilometres (110 mi) although it is not clearly visible in all InSAR data. This joint uplift-subsidence has been called a " sombrero pattern" and the subsidence may reflect either a sideward or an upward migration of magma . A second, shallow subsidence area has been found south of Uturuncu, which may relate to changes in

4329-466: 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

4440-493: Is uplifting. The uplift may have begun around 1965 but was first detected in 1992. Between 1992 and 2006, the uplift amounted to 1–2 centimetres per year (0.39–0.79 in/year) in an area 70 kilometres (43 mi) wide, with seasonal variations. There are longer-term changes in the uplift rate, such as a temporary acceleration after a 1998 earthquake, a gradual slowdown either continuing after 2017 or followed by an acceleration to about 9 millimetres per year (0.35 in/year) in

4551-524: The 1883 eruption of Krakatoa , supported by experimental evidence, shows that pyroclastic flows can cross significant bodies of water. However, that might be a pyroclastic surge , not flow, because the density of a gravity current means it cannot move across the surface of water. One flow reached the Sumatran coast as far as 48 kilometres (26 nautical miles) away. A 2006 BBC documentary film, Ten Things You Didn't Know About Volcanoes , demonstrated tests by

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4662-600: 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

4773-807: The Salar de Uyuni . These watercourses are usually confined between steep bedrock walls and are characterized by gravelly beds, anastomosing channels and wetlands that are used to keep llamas and sheep . The eastward subduction of the Nazca Plate beneath the South American Plate has generated three volcanic belts within the Andes , including the Central Volcanic Zone , which spans parts of Peru, Chile, Bolivia and Argentina and includes Uturuncu. Aside from Uturuncu, it includes about 69 Holocene volcanoes in

4884-686: The San Pablo de Lípez municipality of the Sur Lípez area of southern Bolivia , southeast of the town of Quetena and just northeast of the Eduardo Avaroa Andean Fauna National Reserve in the Cordillera de Lípez . The region is almost uninhabited and the volcano was little known until ongoing large-scale ground deformation was discovered in the early 21st century; since then scientific interest and activity has increased, including

4995-639: The basal flow hugs the ground and contains larger, coarse boulders and rock fragments, while an extremely hot ash plume lofts above it because of the turbulence between the flow and the overlying air, admixing and heating cold atmospheric air causing expansion and convection. Flows can deposit less than 1 meter to 200 meters in depth of loose rock fragment. The kinetic energy of the moving cloud will flatten trees and buildings in its path. The hot gases and high speed make them particularly lethal, as they will incinerate living organisms instantaneously or turn them into carbonized fossils: Testimonial evidence from

5106-792: The core–mantle boundary , 3,000 kilometres (1,900 mi) deep within Earth. This results in hotspot volcanism , of which 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,

5217-824: 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

5328-520: The 1600 eruption of Huaynaputina in Peru; this possibility has resulted in international media attention and in popular culture; the volcano's threat is depicted in the 2016 film Salt and Fire . Evidence does not unequivocally indicate that a future super-eruption such as past events in the region is possible and there is no indication for a near-future eruption, but there is potential for a smaller eruption. Volcano#Dormant and reactivated A volcano

5439-646: The 250,000 ± 5,000   eruption, and Holocene or recent eruptions have not been reported. At first, it was proposed that postglacial lavas existed, but glaciation has affected the youngest lava flows. The volcano is considered to be dormant . Active fumaroles occur in two fields below the summit, with a number of tiny vents located between the two summit peaks; vapour emissions are visible from close distance. The summit fumaroles have temperatures of less than 80 °C (176 °F). Their gases contain large quantities of carbon dioxide , water and larger amounts of hydrogen sulfide than sulfur dioxide perhaps due to

5550-403: The Altiplano–Puna magmatic body, which generates melts through differentiation of basaltic magmas first to andesites and then to dacites before being transferred to the shallow crust below Uturuncu from where it was then erupted through buoyancy -dependent processes. Magma composition has been stable over the history of the volcano. Modern Uturuncu features no glaciers ; however, perennial ice

5661-532: The Central Volcanic Zone but on a global scale it is unusual both for its long duration and its spatial extent, and in the case of Uturuncu demonstrates the continuing activity of the Altiplano–Puna magmatic body. There is no evidence for a net uplift in the geomorphology of the region, and findings in the terrain around Uturuncu indicate that this uplift certainly began less than 1,000 years ago and likely also less than 100 years ago. The uplift might be either

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5772-674: The Lipez-Coranzuli and Pastos Grandes-Cojina lineament that passes through Uturuncu. The geological history of the region is complex. After subduction commenced in the Jurassic , 26 mya ago the breakup of the Farallon Plate into the Cocos Plate and the Nazca Plate was accompanied by an increased subduction rate and the onset of the Andean Orogeny . This subduction process at first involved

5883-612: 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

5994-496: The Puna region miners and native inhabitants may have ascended it earlier. A former sulfur mine named "Uturuncu" is situated on the mountain, close to the summit, and was considered to be one of the highest in the world. It reportedly contained reserves of 50   million tons of ore , consisting mainly of sulfur with some realgar which is dispersed among tephra deposits and contains large amounts of arsenic . A winding road that served

6105-609: 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

6216-503: 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

6327-402: 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

6438-478: The density of the current, the volcanic output rate, and the gradient of the slope. The word pyroclast is derived from the Greek πῦρ ( pýr ), meaning "fire", and κλαστός ( klastós ), meaning "broken in pieces". A name for pyroclastic flows that glow red in the dark is nuée ardente (French, "burning cloud"); this was notably used to describe the disastrous 1902 eruption of Mount Pelée on Martinique ,

6549-478: The depth range of the Altiplano-Puna magmatic body but occur below it, implying that it is underlaid by brittle, cold crust. Whether there are long-term trends in seismic activity is difficult to estimate as the detection and reconnaissance techniques of seismic activity at Uturuncu have changed over time. This amount of seismic activity is large when compared to neighbouring volcanoes and the seismic activity may be

6660-567: The emission of voluminous lava flows ( 0.1–10 km ) between pauses lasting between 50,000 and 180,000   years. The mean eruption rate was less than 60,000 cubic metres per year (2,100,000 cu ft/a)-270,000 cubic metres per year (9,500,000 cu ft/a), much less than other rhyolitic volcanoes. There is no evidence of large ignimbrite eruptions nor of large flank collapses but some lavas may have interacted with water or ice as they were erupted and were reportedly emplaced over moraines. No large effusive eruptions have occurred since

6771-772: 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

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6882-400: The few years before 2017, or constant deformation between 2010 and 2018. As of 2023, uplift was still underway. The overall volume change between 1992 and 2006 was about 1 cubic metre per second (35 cu ft/s), with a total volume change of about 0.4 km ; such rates are typical for intrusions in the Altiplano–Puna volcanic complex and historical lava dome eruptions and might reflect

6993-498: The first two appear to be derived from country rocks while the third is a by-product of the magma generation process. Additionally, the occurrence of cumulates , gabbros , hornfels , limestones and sandstones as xenolithic phases has been reported. Mixing processes involving hotter or more mafic magmas played a role in the genesis of Uturuncu rocks, as did fractional crystallization processes and contamination with crustal rocks. The origin of these magmas appears to relate to

7104-431: 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

7215-440: The form of inclusions within the dacite). Rocks are vesicular or porphyritic and contain phenocrysts of biotite , clinopyroxene , hornblende , ilmenite , magnetite , orthopyroxene , plagioclase and quartz along with apatite , monazite and zircon within a rhyolite groundmass , and define a potassium -rich calc-alkaline suite. Xenoliths consisting of gneiss , igneous rocks and norites have also been found;

7326-592: 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

7437-568: 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

7548-545: The global last glacial maximum. Afterwards, not much retreat occurred until 18,000   years ago. During the Pleistocene, the snow line was about 0.7–1.5 kilometres (0.43–0.93 mi) lower than today. Conversely, the uppermost of these moraines is about 16,000–14,000   years old and correlates to a glacial advance in the Altiplano that has been linked to the maximum growth of the former Lake Tauca north of Uturuncu and

7659-461: 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

7770-492: 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

7881-423: The largest reservoir of magma in the continental crust of Earth . The Altiplano–Puna magmatic body is the source of magmas for many of the volcanoes in the Altiplano–Puna volcanic complex. Its magma is extremely water-rich, consisting of about 10% water by weight; in addition, about 500 000  km of brine are contained in the rocks underneath Uturuncu. Uturuncu has erupted dacite (as well as andesite in

7992-479: The last eruption was 250,000 years ago; since then Uturuncu has not erupted but active fumaroles occur in the summit region, between the two summits. The volcano rises within the Altiplano–Puna volcanic complex , a larger province of large volcanoes and calderas which over the last few million years (mya) have emplaced about 10 000  km of ignimbrites in sometimes very large eruptions. Underneath it lies

8103-541: The last two mya, the Laguna Colorada , Tatio and Puripica Chico ignimbrites were erupted in the surrounding terrain. The Atana (4   mya old) and Pastos Grandes (3   mya old) ignimbrites are other large ignimbrites in the area while the San Antonio ignimbrite (10.33   ±   0.64   mya old) is more sparse. The Altiplano–Puna volcanic complex is underpinned at about 20 kilometres (12 mi) depth by

8214-437: The latter being filtered out by a hydrothermal system. The fumaroles have emplaced abundant sulfur, and silification has been observed. Relatively invariant temperature anomalies (hot spots) have been recorded by satellites on Uturuncu between its two summit peaks; these temperature anomalies of about 15 °C (27 °F) are among the largest fumarole fields visible to satellites. The existence of intense fumarolic activity on

8325-485: The lighter material) along on a bed of steam at an even faster pace than before. During some phases of the Soufriere Hills volcano on Montserrat, pyroclastic flows were filmed about 1 km ( 1 ⁄ 2  nmi) offshore. These show the water boiling as the flow passes over it. The flows eventually built a delta, which covered about 1 km (250 acres). Another example was observed in 2019 at Stromboli when

8436-419: 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

8547-545: 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

8658-415: 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

8769-438: 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

8880-452: 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

8991-867: 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

9102-466: The northwestern slope at 5,500 metres (18,000 ft) was already reported in 1956. A spring on the northwestern flank produces water with temperatures of 20 °C (68 °F) and may be identical to the Campamento Mina Uturuncu spring which in 1983 was reported to produce 21 °C (70 °F) warm water at a rate of 5–7 litres per second (0.18–0.25 cu ft/s). The presence of

9213-400: The occurrence of pyroclastic flow deposits was reported at first, later research has not found any evidence of explosive eruptions . Aside from volcanic deposits there are also traces of glaciation that has smoothened the slopes of Uturuncu, as well as Pleistocene and Holocene alluvium and colluvium . Several lakes surround Uturuncu. Mama Khumu lies on the eastern foot of Uturuncu and

9324-541: 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

9435-420: 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

9546-471: 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

9657-462: 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

9768-425: 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

9879-595: 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

9990-590: The region is about 65 kilometres (40 mi) thick. Volcanic activity in the area occurred between 15   and 10   mya ago. Cerro San Antonio, a Miocene volcano with a westward-opening collapse scar, lies just north of Uturuncu. It is heavily eroded and 3 mya old. Other volcanoes from east counterclockwise to west are the Cerro Panizos caldera , Cerro Lípez , Suni K'ira and Quetena volcanoes as well as many more minor volcanic centres. Many of them formed along northwest–southeast trending lineaments such as

10101-420: The region range between 0–5 °C (32–41 °F) and in 1963 the snowline was reported to exceed 5,900 metres (19,400 ft) elevation. The regional vegetation is relatively sparse at high elevations. Polylepis trees are found on the lower slopes of the volcano; the trees reach 4 metres (13 ft) in height and form forests. They have been used as a source of tree ring climate records . Uturuncu

10212-435: 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

10323-485: 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

10434-441: The so-called Altiplano–Puna magmatic body , a large sill formed by partially molten rocks. Starting in 1992, satellite observations have indicated a large area of regional uplift centered on Uturuncu, which has been interpreted as an indication of large-scale magma intrusion under the volcano. This might be a prelude to large-scale volcanic activity, including " supervolcanic " activity and caldera formation. Uturuncu lies in

10545-622: 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

10656-413: The sulfur mine leads up the mountain, and roads pass along the northern, eastern and southwestern feet of Uturuncu. At an elevation of 6,008 metres (19,711 ft), Uturuncu is the highest mountain in southwestern Bolivia. It dominates the regional geomorphology, rising about 1,510–1,670 metres (4,950–5,480 ft) above the surrounding terrain and presenting a good view of the surrounding mountains from

10767-462: The summit area, 250,000 ± 5,000   for the youngest dated lava flow found just south-southeast of the summit and 544,000   years for the Lomo Escapa lava flow, while the aligned lava domes have been dated to be between 549,000 ± 3,000 and 1,041,000 ± 12,000   years old. Overall, Uturuncu was active for about 800,000   years. Volcanic eruptions at Uturuncu were effusive and involved

10878-435: The summit form a northwest–southeast trending alignment that appears to be an older volcanic system; the southern of these domes have volumes of about 1 km and the western dome bears traces of a large collapse. The broad edifice of the volcano covers an area of about 400 square kilometres (150 sq mi) and has a volume of 85 km – 50 km . It appears to consist entirely of lava flows and lava domes; while

10989-408: The summit. The volcano has two summit peaks, one 5,930 metres (19,460 ft) and the other 6,008 metres (19,711 ft) high. They are about 1 kilometre (0.62 mi) apart and separated by a saddle that is 5,700 metres (18,700 ft) high. Uturuncu is a stratovolcano with remnants of a crater , and consists of lava domes and lava flows erupted from a number of vents in the central part of

11100-406: 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

11211-436: The temperature is still lethally high. Cold pyroclastic surges can occur when the eruption is from a vent under a shallow lake or the sea. Fronts of some pyroclastic density currents are fully dilute; for example, during the eruption of Mount Pelée in 1902, a fully dilute current overwhelmed the city of Saint-Pierre and killed nearly 30,000 people. A pyroclastic flow is a type of gravity current ; in scientific literature, it

11322-434: 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

11433-444: 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

11544-431: 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

11655-439: The volcano, and seismic swarms lasting minutes to hours with up to 60 earthquakes occur several times per month. The intensities of the earthquakes reach magnitude M L 3.7. Most of this seismic activity occurs below the summit of Uturuncu around sea level and some earthquakes appear to relate to the northwest-southeast tectonic trend of the region although swarms occur in several areal clusters. Earthquakes are missing from

11766-428: The volcano. About 105 lava flows propagate outward from the central sector of the volcano, reaching lengths of 15 kilometres (9.3 mi) and featuring levees , flow ridges and steep, blocky fronts over 10 metres (33 ft) thick. The northernmost lava flow is known as Lomo Escapa and with a length of 9 kilometres (5.6 mi) it is also the largest lava flow at Uturuncu. Five lava domes south, west and northwest of

11877-492: 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

11988-424: 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

12099-548: Was active during the Pleistocene. A lower unit emplaced during the lower and middle Pleistocene (890,000–549,000   years ago) makes up most of the peripheral sectors of the volcano, while an upper unit of middle to upper Pleistocene age (427,000–271,000   years ago) forms its central sector and is less extensive. Several rocks have been dated through argon-argon dating and have yielded ages ranging from 1,050,000 ± 5,000   to 250,000 ± 5,000   years ago. Dates of 271,000 ± 26,000   years ago have been obtained from

12210-421: 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

12321-544: Was reported in 1956, remnants of snow in 1971, the existence of sporadic snow fields in 1994, and the summit area is occasionally ice-covered. Evidence of past glaciation such as glacial striations , glacially eroded valleys, both recessional and terminal moraines and roches moutonnées can be found on the northern, eastern and southern flanks of Uturuncu. The past glaciation of Uturuncu was not extensive, owing to its steep flanks. One valley on Uturuncu's southwestern flank has been subject to glaciology studies, which identified

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