Irruputuncu is a

volcano A volcano is commonly defined as a vent or fissure 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. On Earth, volcanoes are most oft ...

in the commune of Pica, Tamarugal Province,

Tarapacá Region The Tarapacá Region (, ) is one of Chile's 16 first-order Administrative divisions of Chile, administrative divisions. It comprises two provinces, Iquique Province, Iquique and Tamarugal Province, Tamarugal. It borders the Chilean Arica y Par ...

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

, as well as

San Pedro de Quemes Municipality San Pedro de Quemes () is the second Municipalities of Bolivia, municipal section of the Nor Lípez Province in the Potosí Department in Bolivia. Its seat is San Pedro de Quemes. Geography The municipality lies at the Salar de Uyuni, Uyuni sal ...

, Nor Lípez Province,

Potosí Department Potosí (; Southern Quechua, Quechua: ''P'utuqsi''; Aymara language, Aymara: ''Putusi'') is a Departments of Bolivia, department in southwestern Bolivia. Its area is 118,218 km2 and its population is 856,419 (2024 census). The capital is the ...

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

. The mountain's summit is high and has two summit craters—the southernmost -wide one has active

fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or another rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...

s. The volcano also features

lava flows Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or unde ...

block and ash flow A block and ash flow or block-and-ash flow is a flowing mixture of volcanic ash and large (>26 cm) angular blocks commonly formed as a result of a gravitational collapse of a lava dome or lava flow. Block and ash flows are a type of pyroclastic fl ...

s and several

lava dome In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...

s. The volcano is part of the

Andean The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long and wide (widest between 18°S ...

Central Volcanic Zone The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. It is formed as a result of subduction of the Nazca plate and Antarctic plate underneath the South Americ ...

(CVZ). The volcano has been active during the

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

and

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

, with major eruptions occurring 258.2 ± 48.8 ka ago, between 55.9 ka and 140 ka ago and 1570 ± 900 BP (380 ± 900 AD), which were accompanied by the formation of ignimbrites. Historical volcanic activity is less clear; an eruption in 1989 is considered unconfirmed. Plumes linked to phreatomagmatic eruptive activity were observed on 26 November 1995 and 1 September 2003.

Seismic activity An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

is also observed on Irruputuncu, and ongoing fumarolic activity releasing of has left sulfur deposits in the active crater. The Central Volcanic Zone is thinly inhabited and most volcanoes are not under reconnaissance, but Irruputuncu is watched by the Chilean SERNAGEOMIN geologic service. The possibility of

geothermal energy Geothermal energy is thermal energy extracted from the crust (geology), crust. It combines energy from the formation of the planet and from radioactive decay. Geothermal energy has been exploited as a source of heat and/or electric power for m ...

production from the volcano has been examined.

Etymology and alternative names

The name Irruputuncu derives from Aymara ''iru'' spiny Peruvian feather grass and ''phutunqu'' a small vessel or a hole, pit, crater. Alternative names are ''Irruputunco'' and ''Iruputuncu''.

Geography and geology

Regional setting

The

subduction Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second p ...

of the

Nazca Plate The Nazca plate or Nasca plate, named after the Nazca region of southern Peru, is an oceanic list of tectonic plates, tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction, along the Peru– ...

and the Antarctic Plate beneath the western side of

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

has generated a belt of volcanic activity named the

Andean Volcanic Belt The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. It is formed as a result of subduction of the Nazca plate and Antarctic plate underneath the South Americ ...

. The belt is separated in a number of volcanic zones by segments lacking recent volcanic activity; in these segments, shallow subduction of the plates presumably displaces the

asthenosphere The asthenosphere () is the mechanically weak and ductile region of the upper mantle of Earth. It lies below the lithosphere, at a depth between c. below the surface, and extends as deep as . However, the lower boundary of the asthenosphere i ...

away from these segments. The segments with active volcanism are the

Northern Volcanic Zone The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. It is formed as a result of subduction of the Nazca plate and Antarctic plate underneath the South America ...

(NVZ), the

(CVZ), the

Southern Volcanic Zone The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. It is formed as a result of subduction of the Nazca plate and Antarctic plate underneath the South America ...

(SVZ) and the Austral Volcanic Zone (AVZ). The "Volcanoes of the World" catalogue counts about 575 eruptions in the entire volcanic belt. Volcanic activity in the belt is usually linked to the dehydration of the subducting slabs, which causes water and other subducted components to be added to the overlying mantle. In the case of the CVZ, this addition generates magmas that are further modified by the thick crust in the area, forming

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...

s and

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matri ...

Local setting

Volcanism in the CVZ is linked to the subduction of the Nazca Plate beneath the

South American Plate The South American plate is a major tectonic plate which includes the continent of South America as well as a sizable region of the Atlantic Ocean seabed extending eastward to the African plate, with which it forms the southern part of the Mid ...

. This subduction within the past 27.5 mya has triggered a thickening of the crust and

orogeny Orogeny () is a mountain-mountain formation, building process that takes place at a convergent boundary, convergent plate margin when plate motion compresses the margin. An or develops as the compressed plate crumples and is tectonic uplift, u ...

. Approximately 44 volcanic centres that are either active or potentially active are found in the CVZ. Some centres are fumarolically active; these include Alitar,

Lastarria Lastarria is a high stratovolcano that lies on the border between Chile and Argentina. It is remote, and the surroundings are uninhabited but can be reached through an unpaved road. The volcano is part of the Central Volcanic Zone, one of the ...

and Tacora. Irruputuncu and other volcanoes including Guallatiri,

Isluga Isluga () is a stratovolcano located in Colchane, west of the Chile-Bolivia border and at the west end of a group of volcanoes lined up in an east-west direction, which also includes the volcanoes Cabaray and Tata Sabaya. Isluga has an elongate ...

Lascar A lascar was a sailor or militiaman from the Indian subcontinent, Southeast Asia, the Arab world, British Somaliland or other lands east of the Cape of Good Hope who was employed on European ships from the 16th century until the mid-20th centur ...

and San Pedro have displayed phreatic or magmatic-phreatic activity. The arid climate of the area has led to good preservation of volcanic structures. A small gap about wide, which is known as the "Pica gap" but includes the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Alto Toroni Sillajhuay (also known as Sillajguay or Alto Toroni) is a volcano on the border between Bolivia and Chile. It is part of a volcanic chain that stretches across the border between Bolivia and Chile and forms a mountain massif that is in part cove ...

volcano that features vigorous seismic activity, separates Irruputuncu from Isluga in the north. Irruputuncu is part of an elliptical alignment of volcanoes that extends to the east, which may be linked to a cup-shaped intrusion in the crust. Older Pliocene volcanoes around Irruputuncu are Laguna volcano to the northeast and Bofedal to the southeast. Irruputuncu lies at the end of a chain of volcanoes that trends northeastward away from it. It may be part of a larger volcano system in the area. The volcanic complex sits on top of

ignimbrite Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...

layers, the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

Ujina and Pleistocene Pastillos Ignimbrites. These ignimbrites are and thick, the former is a welded ignimbrite that was erupted 9.3 ± 0.4 mya and the latter in two stages 0.79 ± 0.2 - 0.73 ± 0.16 mya and 0.32 ± 0.25 mya. In terms of composition, the Ujina is pink-grey crystals and pumice and the Pastillos a gray-white pumice forming the lower member and the upper member of the Pastillos contains cinerites with accessory

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone and shale. Most of the particles of which the stone is composed are less than and are too small to ...

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility. Although its permeabil ...

s and

diatomite Diatomaceous earth ( ), also known as diatomite ( ), celite, or kieselguhr, is a naturally occurring, soft, siliceous sedimentary rock that can be crumbled into a fine white to off-white powder. It has a particle size ranging from more than 3 ...

s. Further volcanic rocks beneath Irruputuncu are hydrothermally altered dacites that may be part of an older now deeply eroded edifice. Irruputuncu is a relatively small, high volcano, which covers a surface area of with a volume of and has two summit craters, of which the -wide southwestern one is fumarolically active. Crater II, the youngest crater, is surrounded by the Crater lava flows that form lava domes and seven short lava flows long, thick and with a total volume of emitted from it. They have weakly developed ogives and there is no evidence of glacial activity anywhere on the volcano. The current edifice is constructed within a collapsed amphitheater of an older edifice. Overall, the volcano has a pristine morphology. Block and ash flows and thick lava flows of high viscosity form the stratocone. A

rhyolitic Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals ( phenocrysts) in an otherwise fine-grained groundmass. The miner ...

ignimbrite is found southwest of the volcano. The oldest lava flows on the northern and eastern side of the volcano were erupted from a northeastern crater named Crater I and are thick with erosional features and preserved ogives. They have a volume of around . The younger flows are known as Queñoas lava flows; they form six distinct flows on the western sides of the volcano. They have different appearances depending on the side; the northwestern flows form lateral lava

levees A levee ( or ), dike (American English), dyke (British English; see spelling differences), embankment, floodbank, or stop bank is an elevated ridge, natural or artificial, alongside the banks of a river, often intended to protect against fl ...

and ogives and reach thicknesses of while the other flows have lobate structures with thicknesses of . These thicknesses may be the result of high-viscosity magma and/or low eruption rates. A major block and ash deposit with the volume of covers a surface area of ; it was highly mobile considering the distances it reached from the volcano on all three sides of the younger crater. It contains large blocks and has long flow ridges. A second block and ash flow formed by the collapse of lava domes covers . Its blocks are somewhat smaller and its ridges are poorly developed. Fissure eruptions have generated large lava flows from the flanks. The El Pozo ignimbrite covers a surface area of northwest of the volcano with a thickness of , an approximate volume of and is probably linked to Irruputuncu, in which case it would be the volcano's oldest unit. Irruputuncu underwent a flank collapse that subdivides the volcano into two edifices, the older Irruputuncu I and the younger Irruputuncu II, about 140 ± 40 ka ago. This flank collapse extends southwest from the older crater I and is about thick. It was formed by the collapse of the southwestern flank and forms three distinct units formed by hummock-forming lava blocks and flow ridges up to long. Each stage is associated with an individual crater named Crater I and Crater II. The flank collapse was probably produced by oversteepening of the volcano or by asymmetric growth. Subsequent activity of the volcano has completely filled the scarp. The lack of ground deformation during eruptive activity suggests the

magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it u ...

of Irruputuncu may be more than deep, which may be linked to the thickness of the crust beneath the Central Andes, ranging . Irruputuncu displays vigorous fumarolic activity that occupies about half the summit crater and is visible within several . The high fumaroles have temperatures of and are composed mainly by sulfur dioxide, followed by minor amounts of

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist ...

hydrogen chloride The Chemical compound, compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hyd ...

hydrogen fluoride Hydrogen fluoride (fluorane) is an Inorganic chemistry, inorganic compound with chemical formula . It is a very poisonous, colorless gas or liquid that dissolves in water to yield hydrofluoric acid. It is the principal industrial source of fluori ...

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

and

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

. In addition,

argon Argon is a chemical element; it has symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

helium Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is ...

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

and

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

are found. The temperatures of the fumaroles are comparable with or exceed the

boiling point The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding envi ...

at such altitudes. ASTER imagery indicates Irruputuncu's fumarole field has a small surface area with high temperatures. Total sulfur dioxide flux from the volcano is between . The fumarolic activity has left sulfur deposits on the volcano. Sulfur deposits are found in the youngest crater in an area of about , and also form small sulfur flows with

pahoehoe Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or unde ...

-type morphology. Deposits are generally yellow but close to the fumaroles they display different colours depending on their temperatures. Upon exposure to the air they can burn. Gravel and eolian deposits form sedimentary units around the volcano.

Composition

Irruputuncu's rocks consist of andesite- and dacite-containing

hornblende Hornblende is a complex silicate minerals#Inosilicates, inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common ...

and

pyroxene The pyroxenes (commonly abbreviated Px) are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents ions of calcium (Ca), sodium (Na), iron ( ...

. The El Pozo

is pumice-rich and has a composition between trachyandesite and trachydacite. Minerals

amphibole Amphibole ( ) is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is ...

biotite Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron- endmember annite, and the magnesium-endmember phlogopite; more al ...

, hornblende,

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

and plagioclase comprise the rocks. The Irruputuncu I lava flows are composed of trachyandesitic with biotite and plagioclase, while the Queñoas are composed of andesite and trachyandesite. The block and ash flows and Crater lavas consist of solely trachyandesitic rocks. Overall, these rocks belong to the

potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

-rich

calc-alkaline The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic ...

series typical of CVZ volcanoes. The magmas are formed by plagioclase and

clinopyroxene The pyroxenes (commonly abbreviated Px) are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents ions of calcium (Ca), sodium (Na), iron (Fe ...

crystallization with some mixing. Irruputuncu's rocks show minor evidence of crustal contamination, similar to other CVZ volcanoes located within transition zones. Water is the most important component in the volcano's fumarolic gases, comprising 96.05% to 97.95% by volume. Examinations of

deuterium Deuterium (hydrogen-2, symbol H or D, also known as heavy hydrogen) is one of two stable isotopes of hydrogen; the other is protium, or hydrogen-1, H. The deuterium nucleus (deuteron) contains one proton and one neutron, whereas the far more c ...

and

oxygen-18 Oxygen-18 (, Ω) is a natural, stable isotope of oxygen and one of the environmental isotopes. is an important precursor for the production of fluorodeoxyglucose (FDG) used in positron emission tomography (PET). Generally, in the radiopharm ...

content of the water have determined that like the water of fumaroles in other Andean volcanic centres, Irruputuncu water is a mixture of weather-related water and water contained in andesite. The helium isotope ratios indicate the magmatic component dominates the gasses at Irruputuncu, Much of the

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

comes from subducted and crustal

carbonates A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group . ...

. The gases escape from oxidizing magma at and pass through a weakly developed hydrothermal system with temperatures of . Argon isotope ratios appear to be

radiogenic A radiogenic nuclide is a nuclide that is produced by a process of radioactive decay. It may itself be radioactive (a radionuclide) or stable (a stable nuclide). Radiogenic nuclides (more commonly referred to as radiogenic isotopes) form some of ...

Eruptive history

The oldest rocks at Irruputuncu are lavas that have been dated by potassium-argon dating to 10.8 ± 0.6 mya. The oldest component clearly belonging to the volcano is the El Pozo ignimbrite that was erupted 258.2 ± 48.8 ka, forming a multi-layered ignimbrite that was probably generated by the injection of new, hot magma into older, cooler magma. A lava dome on the upper flank on the western side of the volcano is 0.14 ± 0.04 mya old. The block and ash flow between 55.9 ka and 140 ka old, but has not been precisely dated. The Crater lavas are 55.9 ± 26.8 ka old. The block and ash flow on the southwestern flank was formed 1570 ± 900 years BP.

Tephra Tephra is fragmental material produced by a Volcano, volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, ...

layers found in the Salar Grande area of the

Atacama Desert The Atacama Desert () is a desert plateau located on the Pacific Ocean, Pacific coast of South America, in the north of Chile. Stretching over a strip of land west of the Andes Mountains, it covers an area of , which increases to if the barre ...

may originate at Irruputuncu. Historical activity of Irruputuncu is unclear. An unconfirmed eruption was reported in Bolivia in December 1989 and fumarolic activity in the crater was reported on 25 March 1990. Another report indicates activity in December 1960. Eruption plumes on Irruputuncu, which reached an altitude of and dispersed to the east, probably triggered by phreatomagmatic activity, were seen on 26 November 1995. The plume's colour changed between black and white repeatedly. Another plume was observed on 1 September 2003; neither of these incidents were accompanied with noticeable ground deformation. Like some other volcanoes in the area, activity at Irruputuncu has not been preceded by ground inflation during historical times. Several theories, including

aliasing In signal processing and related disciplines, aliasing is a phenomenon that a reconstructed signal from samples of the original signal contains low frequency components that are not present in the original one. This is caused when, in the ori ...

of the imagery, have been proposed to explain the lack of ground inflation. Ongoing seismic activity at a rate of about 56 earthquakes per 10 days recorded in two separate phases, November 2005-March 2006 and April 2010-February 2011 respectively and including one seismic swarm during the first measurement period, has been recorded at Irruputuncu. Some of this activity may be caused by mine blasts from nearby mining projects. Geothermal anomalies of about have been noted, including

hot spring A hot spring, hydrothermal spring, or geothermal spring is a Spring (hydrology), spring produced by the emergence of Geothermal activity, geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow ...

s west and northwest of the volcano.

Threats and geothermal prospecting

With the exception of Peruvian volcanoes such as Misti, most of the volcanoes of the CVZ are in remote areas and are not closely watched. Irruputuncu is a remote volcano; a road between

Iquique Iquique () is a port List of cities in Chile, city and Communes of Chile, commune in northern Chile, capital of both the Iquique Province and Tarapacá Region. It lies on the Pacific coast, west of the Pampa del Tamarugal, which is part of the At ...

and the Collahuasi mine and mining infrastructure west of the volcano are the major sites that could be affected by future activity. The 1995 eruption drew attention to volcanic hazards in the Western Cordillera. In Chile, Irruputuncu is surveilled by SERNAGEOMIN, which produces regular status reports and which in 2020 classified it as a "type III" volcano, owing to its proximity to Collahuasi mine. There are also hazard maps available. Future eruptions could involve both the emission of lava domes and lava flows or

explosive eruption In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a Viscosity, viscous ...

s; the western and northwestern flanks would be the most affected.

Olca Olca is a stratovolcano on the border of Chile and Bolivia. It lies in the middle of a 15 km long ridge composed of several stratovolcanos. Cerro Minchincha lies to the west and Paruma to the east. It is also close to the pre-Holocene Cerro ...

and Irruputuncu have been examined as a potential location for a geothermal energy project involving a company named . A geothermal prospect made at the base of Irruputuncu indicated the presence of water at temperatures of up to in a deep reservoir; the volcano was thus classified as "highly favourable area".

Climate and vegetation

'' Polylepis tarapacana'' trees on Irruputuncu have been used (through

tree rings Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed in a tree. As well as dating them, this can give data for dendroclimatology, the study of climate ...

) to reconstruct atmospheric

radiocarbon Carbon-14, C-14, C or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic matter is the basis of the radiocarbon dating method pioneered by Willard Libby and coll ...

concentrations and regional climatic variability, including

El Niño–Southern Oscillation El Niño–Southern Oscillation (ENSO) is a global climate phenomenon that emerges from variation in winds and sea surface temperatures over the tropical Pacific Ocean. Those variations have an irregular pattern but do have some semblance of cyc ...

variability.