Sabancaya
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Sabancaya is an active
stratovolcano A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...
in the
Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
of southern
Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...
, about northwest of
Arequipa Arequipa (; Aymara and qu, Ariqipa) is a city and capital of province and the eponymous department of Peru. It is the seat of the Constitutional Court of Peru and often dubbed the "legal capital of Peru". It is the second most populated city ...
. It is considered part of the
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 ...
of the Andes, one of the three distinct volcanic belts of the Andes. The Central Volcanic Zone includes a number of volcanoes, some of which like
Huaynaputina Huaynaputina ( ; ) is a volcano in a volcanic high plateau in southern Peru. Lying in the Central Volcanic Zone of the Andes, it was formed by the subduction of the oceanic Nazca Plate under the continental South American Plate. Huaynaputina ...
have had large eruptions and others such as Sabancaya and
Ubinas Ubinas is an active stratovolcano in the Moquegua Region of southern Peru, approximately east of the city of Arequipa. Part of the Central Volcanic Zone of the Andes, it rises above sea level. The volcano's summit is cut by a and caldera, wh ...
have been active in historical time. Sabancaya forms a volcanic complex together with
Hualca Hualca Hualca Hualca (possibly from Aymara and Quechua ''wallqa'' collar) is an extinct volcano in Arequipa Region in the Andes of Peru. It has a height of . It is located at the Peruvian province of Caylloma. Geography and geomorphology Hualca H ...
to the north and
Ampato Ampato (possibly from Quechua ''hamp'atu'' or from Aymara ''jamp'atu'', both meaning "frog") is a dormant stratovolcano in the Andes of southern Peru. It lies about northwest of Arequipa and is part of a north-south chain that includes the volc ...
to the south and has erupted
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 predomi ...
and
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. ...
. It is covered by a small
ice cap In glaciology, an ice cap is a mass of ice that covers less than of land area (usually covering a highland area). Larger ice masses covering more than are termed ice sheets. Description Ice caps are not constrained by topographical features ...
which leads to a risk of
lahar A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley. Lahars are extreme ...
s during eruptions. Sabancaya has generated numerous long
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 un ...
especially during the early
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
, while activity in the later Holocene has been more
explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...
. Historical reports indicate eruptions during the 18th century. The volcano returned to activity in 1986, culminating in a large eruption in 1990. Since then it has been continuously active with the emission of ash and gas.


Name

The name "''Sabancaya''" is
Quechua Quechua may refer to: *Quechua people, several indigenous ethnic groups in South America, especially in Peru *Quechuan languages, a Native South American language family spoken primarily in the Andes, derived from a common ancestral language **So ...
and means ''tongue of fire'' or ''spitting volcano'', likely a reference to the eruptive activity. The name is attested from 1595, implying that volcanic activity was observed since that date.


Geography and geomorphology

Sabancaya lies about northwest of
Arequipa Arequipa (; Aymara and qu, Ariqipa) is a city and capital of province and the eponymous department of Peru. It is the seat of the Constitutional Court of Peru and often dubbed the "legal capital of Peru". It is the second most populated city ...
. The Rio Colca valley is located north of the Sabancaya-Hualca Hualca-Ampato volcano complex. The principal economic activities in the area are agriculture, animal husbandry, mining and tourism.


Regional

The
subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...
of the
Nazca Plate The Nazca Plate or Nasca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction, along the Peru–Chile Trench, of the Na ...
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-A ...
in the Peru-Chile Trench leads to volcanic activity in the Andes. This volcanic activity presently occurs in three segments, the Northern Volcanic Zone, the Central Volcanic Zone and the Southern Volcanic Zone. There is an additional volcanic belt south of the Southern Volcanic Zone, the Austral Volcanic Zone. Sabancaya is located in the
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 ...
of the Andes, which extends through southern Peru. Many volcanoes in the Central Volcanic Zone are poorly known, owing to their remote locations and adverse conditions such as high altitude. Sabancaya is part of a series of volcanoes that line the southwestern coast of Peru at a distance of roughly from the shore. Of these volcanoes, Sabancaya,
El Misti Misti, also known as Putina or Guagua Putina, is a stratovolcano of andesite, dacite, and rhyolite located in southern Peru near the city of Arequipa. With its seasonally snow-capped, symmetrical cone, Misti stands at above sea level and lies betw ...
,
Ubinas Ubinas is an active stratovolcano in the Moquegua Region of southern Peru, approximately east of the city of Arequipa. Part of the Central Volcanic Zone of the Andes, it rises above sea level. The volcano's summit is cut by a and caldera, wh ...
,
Huaynaputina Huaynaputina ( ; ) is a volcano in a volcanic high plateau in southern Peru. Lying in the Central Volcanic Zone of the Andes, it was formed by the subduction of the oceanic Nazca Plate under the continental South American Plate. Huaynaputina ...
,
Ticsani Ticsani is a volcano in Peru northwest of Moquegua and consists of two volcanoes ("Old Ticsani" and "Modern Ticsani") that form a complex. "Old Ticsani" is a compound volcano that underwent a large collapse in the past and shed of mass down the ...
and
Tutupaca Tutupaca is a volcano in the region of Tacna in Peru. It is part of the Peruvian segment of the Central Volcanic Zone, one of several volcanic belts in the Andes. Tutupaca consists of three overlapping volcanoes formed by lava flows and lava dom ...
have been active during historical time. Further volcanoes in the area with
Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
activity are
Sara Sara Sara Sara is a volcano lying between Lake Parinacochas and the Ocoña River in Peru. It is situated in the Parinacochas Province and the Paucar del Sara Sara Province. The volcano formed during the Pleistocene during four different stages of vo ...
, Solimana,
Coropuna Coropuna is a dormant compound volcano located in the Andes mountains of southeast-central Peru. The upper reaches of Coropuna consist of several perennially snowbound conical summits, lending it the name Nevado Coropuna in Spanish. The compl ...
,
Ampato Ampato (possibly from Quechua ''hamp'atu'' or from Aymara ''jamp'atu'', both meaning "frog") is a dormant stratovolcano in the Andes of southern Peru. It lies about northwest of Arequipa and is part of a north-south chain that includes the volc ...
,
Chachani Chachani is a volcanic group in southern Peru, northwest of the city of Arequipa. Part of the Central Volcanic Zone of the Andes, it is above sea level. It consists of several lava domes and individual volcanoes such as Nocarane, along with ...
,
Yucamane Yucamane, Yucamani or Yucumane is an andesitic stratovolcano in the Tacna Region of southern Peru. It is part of the Peruvian segment of the Central Volcanic Zone, one of the three volcanic belts of the Andes generated by the subduction of the ...
, Casiri and
Tacora Tacora is a stratovolcano located in the Andes of the Arica y Parinacota Region of Chile. Near the border with Peru, it is one of the northernmost volcanoes of Chile. It is part of the Central Volcanic Zone in Chile, one of the four volcanic b ...
. All these volcanoes are considered part of the
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 ...
of the Andes, and lie east of the Peru-Chile Trench. Notable among them are Ampato and Coropuna for exceeding a height of , Huaynaputina and El Misti for their large eruptions and Ubinas and Sabancaya for their recent activity. These volcanoes are found in places where
strike-slip fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...
s which delimit the volcanic arc and strike along its length intersect additional faults formed by
extension Extension, extend or extended may refer to: Mathematics Logic or set theory * Axiom of extensionality * Extensible cardinal * Extension (model theory) * Extension (predicate logic), the set of tuples of values that satisfy the predicate * E ...
al tectonics. Such faults, mainly
normal fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...
s, occur around Sabancaya as well and include the Huambo-Cabanaconde, the Huanca, the Ichupampa, the Pampa Sepina, Sepina, Solarpampa and Trigal faults; the volcanoes Ampato and Sabancaya are aligned on this fault, which may thus be responsible for their existence. These fault systems are still active and experience occasional earthquakes and deformation, and their activity appears to be in part triggered by underground magma movements at Sabancaya.


Local

Sabancaya is high and rises above the surrounding terrain. It forms a group of volcanoes with the northern
Hualca Hualca Hualca Hualca (possibly from Aymara and Quechua ''wallqa'' collar) is an extinct volcano in Arequipa Region in the Andes of Peru. It has a height of . It is located at the Peruvian province of Caylloma. Geography and geomorphology Hualca H ...
and the southern
Ampato Ampato (possibly from Quechua ''hamp'atu'' or from Aymara ''jamp'atu'', both meaning "frog") is a dormant stratovolcano in the Andes of southern Peru. It lies about northwest of Arequipa and is part of a north-south chain that includes the volc ...
in the Cordillera Occidental, which tower above the
Colca Canyon The Colca Canyon is a canyon of the Colca River in southern Peru, located about northwest of Arequipa. With a depth of about 1000 - 2000 m (3300 - 6600 ft) (whereas bottom is at cca 2000 m and edges are at 3000 - 4000 metres above the sea lev ...
in the north and the Siguas Valley in the southwest. Ampato and the more heavily eroded Hualca Hualca are the dominant volcanoes of this group, with Sabancaya forming a northeastward extension of the former away from Ampato's summit. There is evidence of age progression from the oldest, Hualca Hualca, over Ampato, to the youngest volcano, Sabancaya. Sabancaya consists of two separate centres that are formed by neighbouring domes, Sabancaya I North and Sabancaya II South. The
summit crater A volcanic crater is an approximately circular depression in the ground caused by volcanic activity. It is typically a bowl-shaped feature containing one or more vents. During volcanic eruptions, molten magma and volcanic gases rise from an unde ...
of the volcano lies between these two domes, with traces of an additional crater just northeast. Despite the presence of an ice cap,
lava flow 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 und ...
s are recognizable in the summit area. They have a total volume of . A set of over 42
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
lava flow 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 und ...
s emanate from the volcano, and cover a surface area of about , with individual lava flows extending up to east and west from between its two neighbours. The lava flows at larger distances are older than the ones close to the vent. These flows are blocky, have lobe structures and reach thicknesses of ; the total thickness of this pile of lava flows is about .
Pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of bu ...
deposits are also found, but they might originate from Ampato rather than Sabancaya. Sabancaya, like its two neighbours, is covered by an
ice cap In glaciology, an ice cap is a mass of ice that covers less than of land area (usually covering a highland area). Larger ice masses covering more than are termed ice sheets. Description Ice caps are not constrained by topographical features ...
which in 1988 extended to distances of from the summit. In 1997, a surface area of was reported. Between 1986 and 2016 the mountain lost over three quarters of its ice cap, and the remaining ice field broke up into several ice bodies.
Moraine A moraine is any accumulation of unconsolidated debris (regolith and rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice shee ...
s at elevations of above sea level testify to the occurrence of more extensive
glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...
during the last ice age between 25,000 and 17,000 years before present; these moraines have diverted some lava flows. Younger moraines are found at higher altitudes, above sea level, and may have formed between 13,000 and 10,000 years ago, shortly after the beginning of the
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
. Earthquake activity has allowed the identification of a candidate magma reservoir beneath Pampa Sepina northeast of Sabancaya about away from the summit. Between 1992 and 1996 this area inflated at a depth of below sea level, indicating that the magma supply system of Sabancaya may not be centered directly below the volcano. Indeed, a phase of ground uplift at Hualca Hualca volcano and earthquake swarms in 1990 and later seismic activity under Hualca Hualca could indicate that the magma chamber of Sabancaya is actually under the neighbouring volcano, a not uncommon phenomenon at volcanoes.


Geology

The tectonic conditions in the region have not been constant over time; at various times the plates approached each other at higher speed, and this led to a compressional tectonic regimen. In the Western Cordillera however, tensional faulting facilitated the occurrence of voluminous volcanism. This faulting is still underway and produces earthquakes in the area. The
basement A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...
of the volcano is formed by
Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...
rocks, which are overlaid by various sediments and volcanic formations of
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...
and
Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...
age. Especially during the
Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...
, the supply of volcanic material was high and dominated the region, forming a volcanic "foot"; the present volcanoes are constructed on this volcanic "foot". This "foot" is made out of an
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 ...
plateau that drops down south. The "foot" beneath Ampato, Hualca Hualca and Sabancaya has been dated 2.2 ±0.15 million years ago, while a lava flow beneath the first and the last of these is about 0.8 ±0.04 million years old.


Composition

Fresh volcanites of Sabancaya consist of
porphyritic Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning all ...
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 predomi ...
and
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. ...
which form a
potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...
-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 mag ...
suite similar to other volcanoes in southern Peru; the andesites occasionally appear as fine-grained enclaves. The rocks are not very vesicular and contain a moderate amount of
phenocryst 300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter ...
s. Minerals encountered in both phenocrysts and groundmass are
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 A ...
,
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 alumino ...
,
hornblende Hornblende is a complex 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 in igneous and metamorphic rocks ...
,
iron oxide Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. All are black magnetic solids. Often they are non-stoichiometric. Oxyhydroxides are a related class of compounds, perhaps the best known of whic ...
,
plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more prope ...
,
pyroxene The pyroxenes (commonly abbreviated to ''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 calcium (Ca), sodium (Na), iron (Fe II) ...
and
titanium oxide Titanium oxide may refer to: * Titanium dioxide (titanium(IV) oxide), TiO2 * Titanium(II) oxide (titanium monoxide), TiO, a non-stoichiometric oxide * Titanium(III) oxide (dititanium trioxide), Ti2O3 * Ti3O * Ti2O * δ-TiOx (x= 0.68–0.75) * Tin ...
; degraded
olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...
is also found. The
magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...
s formed at temperatures of with uncertainties of ; the highest temperatures are associated with the 1992 eruption products. Isotope data indicate that the pre-magmas interacted with the crust at great depths before rising to shallower
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 upw ...
s. In these shallower magma chambers, magma genesis involved processes of magma mixing which formed at least part of the andesites and fractional crystallization which gave rise to the dacites. Partial crystallization and flow events within the magma chamber caused the formation of the andesite enclaves. The total magma production rate of Sabancaya without accounting for repose periods is about . Sabancaya is a source of
volcanic gas Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic ...
es such as and . The amount of water emitted by Sabancaya is noticeably large for a volcano (about ); the source of this water might be an evaporating
hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...
system in the volcano. Together with Ubinas Sabancaya is among the main emitters of and in the Central Volcanic Zone of the Andes and among the top fifteen volcanic emitters on Earth.


Eruptive history

Initially,
Ampato Ampato (possibly from Quechua ''hamp'atu'' or from Aymara ''jamp'atu'', both meaning "frog") is a dormant stratovolcano in the Andes of southern Peru. It lies about northwest of Arequipa and is part of a north-south chain that includes the volc ...
volcano was the active volcano before volcanism shifted to Sabancaya, after a period where both volcanoes erupted. Presently, most activity at Sabancaya occurs in the form of
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 on ...
s and
lava flow 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 und ...
s, one of which is dated to 5,440 ±40 years
before present Before Present (BP) years, or "years before present", is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Becaus ...
on the eastern flank. Additional
surface exposure dating Surface exposure dating is a collection of geochronological techniques for estimating the length of time that a rock has been exposed at or near Earth's surface. Surface exposure dating is used to date glacial advances and retreats, erosion histo ...
has yielded ages of 6,650 ±320 and 6,300 ±310 on various lava flows, indicating that effusive activity started shortly after the beginning of the Holocene although the basal part of the edifice did not exist yet at that time.
Pyroclastic Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroc ...
eruptions are less common and have a low volume, with one such occurrence dated to 8,500 years before present. This tephra layer, along with layers dated 2500-2100  BC, 420–150 BC, 100 BC – 150 AD and between 1200 and 1400 AD, could have originated either on Sabancaya or
Ampato Ampato (possibly from Quechua ''hamp'atu'' or from Aymara ''jamp'atu'', both meaning "frog") is a dormant stratovolcano in the Andes of southern Peru. It lies about northwest of Arequipa and is part of a north-south chain that includes the volc ...
, however. There is evidence that early and middle-Holocene Sabancaya mostly erupted lava, while the late-Holocene volcano was more explosive in its activity. It is possible that the
Inca The Inca Empire (also known as the Incan Empire and the Inka Empire), called ''Tawantinsuyu'' by its subjects, (Quechua for the "Realm of the Four Parts",  "four parts together" ) was the largest empire in pre-Columbian America. The admin ...
performed
human sacrifice Human sacrifice is the act of killing one or more humans as part of a ritual, which is usually intended to please or appease gods, a human ruler, an authoritative/priestly figure or spirits of dead ancestors or as a retainer sacrifice, wherein ...
s in response to eruptions of Sabancaya to calm down the mountain spirits.
Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Cana ...
chronicles mention probable eruptions in 1752 and 1784, which might have left layers of
tephra Tephra is fragmental material produced by a 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, they rem ...
. After the 18th century, the volcano went dormant for about two hundred years during which only fumarolic activity was recorded. In late 1986 an increased
fumarolic A fumarole (or fumerole) is a vent in the surface of the Earth or other 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 ...
activity heralded the onset of a new eruptive period, and satellite images observed the occurrence of black spots where the ice had melted or boiled away. During this time, the death of animals was observed in the area. This period reached a climax in May 1990, when an eruption with a volcanic explosivity index of 2–3 occurred. This eruption threw ash to distances of from the summit and was accompanied by strong earthquake activity and the formation of
eruption column An eruption column or eruption plume is a cloud of super-heated ash and tephra suspended in gases emitted during an explosive volcanic eruption. The volcanic materials form a vertical column or plume that may rise many kilometers into the air a ...
s that reached heights of . The eruption and further activity, through 1990, enlarged the summit crater and caused the formation of new rows of
fumaroles A fumarole (or fumerole) is a vent in the surface of the Earth or other 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 ...
. Chemical analysis, of the volcanic rocks, suggests that this phase of volcanic activity was started by the injection of
mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...
magma into the magma chamber. This eruption displaced between 4,000 and 1,500 people in the region. After the large 1990 eruption, the style of activity at Sabancaya changed towards a frequent occurrence of explosive eruptions with however low output, which threw ballistic blocks to distances of about from the summit crater; this pattern of activity is referred to as "
Vulcanian eruption A Vulcanian eruption is a type of volcanic eruption characterized by a dense cloud of ash-laden gas exploding from the crater and rising high above the peak. They usually commence with phreatomagmatic eruptions which can be extremely noisy due t ...
s". Ash fall from these eruptions induced melting of the glaciers on Ampato, in 1995 exposing the
Mummy Juanita Momia Juanita (Spanish for "Mummy Juanita"), also known as the Lady of Ampato, is the well-preserved frozen body of a girl from the Inca Empire who was killed as a human sacrifice to the Inca gods sometime between 1440 and 1480, when she was appr ...
on the latter volcano. These explosive eruptions became less common over time (from paroxysms every 20–30 minutes to only 5–6 eruptions per day) and the proportional amount of fresh volcanic material increased at first; since 1997 discontinuous eruptions generate steam columns no higher than and ejected material is almost entirely lithic. Satellite imagery has evidenced the occurrence of temperature anomalies on Sabancaya on the scale of , probably owing to fumarolic activity. In March and April 2013,
fumarolic A fumarole (or fumerole) is a vent in the surface of the Earth or other 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 ...
activity and the occurrence of
seismic swarm In seismology, an earthquake swarm is a sequence of seismic events occurring in a local area within a relatively short period. The time span used to define a swarm varies, but may be days, months, or years. Such an energy release is different f ...
s increased leading to local infrastructure being damaged; an eruption occurred in August 2014. This pulse of activity was accompanied by an increased release of , which was being emitted at a rate of in 2014. Ash was emitted by the volcano multiple times through 2014 and 2015, and there has been steady shallow seismic activity since 2013. A further increase of fumarolic activity was observed in 2016, when new fumaroles appeared and sulfur flux increased to sulfur dioxide. Ash eruptions have occurred since 6 November 2016, with an
eruption column An eruption column or eruption plume is a cloud of super-heated ash and tephra suspended in gases emitted during an explosive volcanic eruption. The volcanic materials form a vertical column or plume that may rise many kilometers into the air a ...
high five days later. This renewed activity was accompanied by ground uplift at Hualca Hualca north of Sabancaya, indicating the role of a shared magmatic system between the two volcanoes. Since then, the volcano has been continuously active with numerous explosions every day, which produce
volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcano, volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used t ...
clouds that can rise to elevations of . A persistent gas plume lies above the volcano and repeated emissions of ash have happened, resulting in several alerts for the local population.
Lahar A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley. Lahars are extreme ...
s have been produced in some occasions, without reports of damage. A
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 on ...
began to grow in 2017 within the crater, with unsteady explosive activity and occasional seismic swarms. In 2020, a second lava dome formed in November but it was destroyed between December and February of that year. Ash emissions and seismic activity continued through 2021 and 2022.


Hazards

Sabancaya rises above the valleys of the Colca river and of some tributaries of the Siguas river with about 35,000 people living in them. Sabancaya is particularly dangerous for the Colca river valley, north of the volcano; it is a major
tourism Tourism is travel for pleasure or business; also the theory and practice of touring (disambiguation), touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tour (disambiguation), tours. Th ...
destination in Peru with about 190,000 visitors per year and with the towns Achoma, Cabanaconde,
Chivay Chivay is a town in the Colca valley, capital of the Caylloma province in the Arequipa region, Peru. Located at about 3,600 m above sea level (12,000 ft), it lies upstream of the renowned Colca Canyon. It has a central town square and an ac ...
, Ichupampa, Lari,
Maca MACA or maca can mean: * Maca (plant) Places Geography * Maca District, Peru * Cerro Macá, stratovolcano in the Aisén Region of Chile * Maca River, Romania Outer space * 5228 Máca, a minor planet People * Alain Maca (born 1950), Belgian ...
,
Madrigal A madrigal is a form of secular vocal music most typical of the Renaissance (15th–16th c.) and early Baroque (1600–1750) periods, although revisited by some later European composers. The polyphonic madrigal is unaccompanied, and the number o ...
, Pinchollo, Yanque and others. About 30,000 people live within from the volcano. The flanks of Sabancaya themselves include
road A road is a linear way for the conveyance of traffic that mostly has an improved surface for use by vehicles (motorized and non-motorized) and pedestrians. Unlike streets, the main function of roads is transportation. There are many types of ...
s and a major
power line An overhead power line is a structure used in electric power transmission and distribution to transmit electrical energy across large distances. It consists of one or more uninsulated electrical cables (commonly multiples of three for three-p ...
that comes from the and delivers electricity to southern Peru; all of these could be threatened in an eruption. In the case of a major Plinian eruption, at least 60,000 to 70,000 people would be threatened. Rock fall would affect the area close to the summit domes, as would
pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of bu ...
s; these would be a further hazard to the valleys draining the volcano. The presence of an ice cap is an additional source of danger, as its melting during a volcanic eruption could form hazardous lahars, although the small volume of the ice cap limits their damage potential. The
Majes River Colca River (possibly from Quechua ''qullqa'' deposit) which downstream is called Majes and Camaná is a Peruvian river in the Arequipa Region that flows deep in the rugged Andes of southern Peru. It originates south-east of the village Janq'u Lak ...
and Sihuasi River drainages would be threatened by such mudflows in case of an eruption; the former is the site of a major
irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,00 ...
project. Other dangers from eruptions at Sabancaya are
tephra Tephra is fragmental material produced by a 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, they rem ...
fallout, which can impact the health of people; and lava flows, which however are not much of a threat to humans owing to their slow speed. Volcano monitoring in Peru commenced after the 1986 eruption, with the being created two years later and beginning its work at Sabancaya. The monitoring network around the volcano was expanded after its 2013 eruption. The monitors Sabancaya with infrasound detectors,
seismometer A seismometer is an instrument that responds to ground noises and shaking such as caused by earthquakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The outpu ...
s,
surveillance camera A closed-circuit television camera can produce images or recordings for surveillance or other private purposes. Cameras can be either video cameras, or digital stills cameras. Walter Bruch was the inventor of the CCTV camera. The main purpose o ...
s,
telemetry Telemetry is the in situ data collection, collection of measurements or other data at remote points and their automatic data transmission, transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Gr ...
units and also uses data from
satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...
s and
volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcano, volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used t ...
collectors; it has published a hazard map. In 2005, monitoring commenced of the gas emissions from Sabancaya. Aside from the direct threat of eruptions, Sabancaya also contributes to
air pollution Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different types ...
in the Colca valley, which can damage plants and cause respiratory distress in animals and humans. Ash clouds from Sabancaya frequently impede
air travel Air travel is a form of travel in vehicles such as airplanes, jet aircraft, helicopters, hot air balloons, blimps, gliders, hang gliders, parachutes, or anything else that can sustain flight.
over the region; the volcano is one of the most frequent causes of volcanic ash-related air traffic advisories in the world.


See also

*
List of volcanoes in Peru This is a list of active and extinct volcanoes in Peru. Notes References *John , Volcano LiveVolcanoes of Peru Retrieved December 27, 2007 *Peakware World Mountain Encyclopedia, , Retrieved December 27, 2007 {{Andean volcanoes ...
* Lake Mucurca


References


Sources

* * * * * * * * * * * * * * * {{andean volcanoes Stratovolcanoes of Peru Mountains of Arequipa Region Active volcanoes Andean Volcanic Belt Subduction volcanoes Five-thousanders of the Andes