Huaynaputina

Huaynaputina (English: /ˌwnəpʊˈtnə/ ; Spanish: [wajnapuˈtina]) 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 is a large volcanic crater, lacking an identifiable mountain profile, with an outer stratovolcano and three younger volcanic vents within an -shaped structure that is either a former caldera or a remnant of glacial erosion. The volcano has erupted dacitic magma.

In the Holocene, Huaynaputina has erupted several times, including on 19February 1600 – the largest eruption ever recorded in South America – which continued with a series of events into March. Witnessed by people in the city of Arequipa, it killed at least 1,000–1,500 people in the region, wiped out vegetation, buried the surrounding area with of volcanic rock and damaged infrastructure and economic resources. The eruption had a significant impact on Earth's climate, causing a volcanic winter: temperatures in the Northern Hemisphere decreased; cold waves hit parts of Europe, Asia and the Americas; and the climate disruption may have played a role in the onset of the Little Ice Age. Floods, famines, and social upheavals resulted, including a probable link with the Russian Time of Troubles. This eruption has been computed to measure 6 on the Volcanic Explosivity Index (VEI).

The volcano has not erupted since 1600. There are fumaroles in the amphitheatre-shaped structure, and hot springs occur in the region, some of which have been associated with Huaynaputina. The volcano lies in a remote region where there is little human activity, but about 30,000 people live in the immediately surrounding area, and another one million in the Arequipa metropolitan area. If an eruption similar to the 1600 event were to occur, it would quite likely lead to a high death toll and cause substantial socioeconomic disruption. The Peruvian Geophysical Institute announced in 2017 that Huaynaputina would be monitored by the Southern Volcanological Observatory, and seismic observation began in 2019.

Name

The name Huaynaputina, also spelled Huayna Putina, was given to the volcano after the 1600 eruption. According to one translation cited by the Peruvian Ministry of Foreign Trade and Tourism, Huayna means 'new', and Putina means 'fire-throwing mountain'; the full name is meant to suggest the aggressiveness of its volcanic activity and refers to the 1600 eruption being its first one. Two other translations are 'young boiling one' – perhaps a reference to earlier eruptions – or 'where young were boiled', which may refer to human sacrifices. Other names for the volcano include Chequepuquina, Chiquimote, Guayta, Omate and Quinistaquillas. The volcano El Misti was sometimes confused with and thus referred to mistakenly as Huaynaputina.

Geography

The volcano is part of the Central Volcanic Zone of the Andes. Other volcanoes in this zone from northwest to southeast include Sara Sara, Coropuna, Ampato, Sabancaya, El Misti, Ubinas, Ticsani, Tutupaca and Yucamane. Ubinas is the most active volcano in Peru; Huaynaputina, El Misti, Sabancaya, Ticsani, Tutupaca, Ubinas and Yucamane have been active in historical time, while Sara Sara, Coropuna, Ampato, Casiri and Chachani are considered to be dormant. Most volcanoes of the Central Volcanic Zone are large composite volcanoes that can remain active over the span of several million years, but there are also conical stratovolcanoes with shorter lifespans. In the Central Volcanic Zone, large explosive eruptions with Volcanic Explosivity Index of 6 and higher occur on average every 2,000 to 4,000 years.

Huaynaputina is in the Omate and Quinistaquillas Districts, which are part of the General Sánchez Cerro Province in the Moquegua Region of southern Peru. The town of Omate lies southwest of Huaynaputina. The city of Moquegua is south-southwest of the volcano and Arequipa is to its north-northwest.

The region is generally remote and the terrain extreme, the area around Huaynaputina is not easily accessible and human activity low. Within of Huaynaputina there are a number of small farms. A cattle-grazing footpath leads from Quinistaquillas to the volcano, and it is possible to approach the volcano over surrounding ash plains. The landscapes around the volcano have unique characteristics that make them an important geological heritage.

Structure

Huaynaputina lies at an elevation of about . It consists of an outer composite volcano, or stratovolcano, and three younger volcanic vents nested within an amphitheatre that is wide and deep. This horseshoe-shaped structure opens eastwards and is set in the older volcano at an elevation of . The amphitheatre lies at the margin of a rectangular high plateau that is covered by about thick ash, extending over an area of . The volcano has generally modest dimensions and rises less than above the surrounding terrain, but the products of the volcano's 1600 eruption cover much of the region especially west, north and south from the amphitheatre. These include pyroclastic flow dunes that crop out from underneath the tephra. Deposits from the 1600 eruption and previous events also crop out within the amphitheatre walls. Another southeastward-opening landslide scar lies just north of Huaynaputina.

One of these funnel-shaped vents is a trough that cuts into the amphitheatre. The trough appears to be a remnant of a fissure vent. A second vent appears to have been about wide before the development of a third vent, which has mostly obscured the first two. The third vent is steep-walled, with a depth of ; it contains a pit that is wide, set within a small mound that is in part nested within the second vent. This third vent is surrounded by concentric faults. At least one of the vents has been described as an ash cone. A fourth vent lies on the southern slope of the composite volcano outside of the amphitheatre and has been described as a maar. It is about wide and deep and appears to have formed during a phreatomagmatic eruption. These vents lie at an elevation of about , making them among the highest vents of a Plinian eruption in the world.

Slumps have buried parts of the amphitheatre. Dacitic dykes crop out within the amphitheatre and are aligned along a northwest–south trending lineament that the younger vents are also located on. These dykes and a dacitic lava dome of similar composition were formed before the 1600 eruption. Faults with recognizable scarps occur within the amphitheatre and have offset the younger vents; some of these faults existed before the 1600 eruption while others were activated during the event.

Surroundings

The terrain west of the volcano is a high plateau at an elevation of about ; north of Huaynaputina the volcano Ubinas and the depression of Laguna Salinas lie on the plateau, while the peaks Cerro El Volcán and Cerro Chen are situated south of it. The lava dome Cerro El Volcán and another small lava dome, Cerro Las Chilcas, lie south from Huaynaputina. Northeast-east of Huaynaputina, the terrain drops off steeply (vertically and horizontally) into the Río Tambo valley, which rounds Huaynaputina east and south of the volcano. Some tributary valleys join the Río Tambo from Huaynaputina; clockwise from the east these are the Quebradas Huaynaputina, Quebrada Tortoral, Quebrada Aguas Blancas and Quebrada del Volcán. The Río Tambo eventually flows southwestward into the Pacific Ocean.

Geology

The oceanic Nazca tectonic plate is subducting at a rate of beneath the continental part of the South American tectonic plate; this process is responsible for volcanic activity and the uplift of the Andes mountains and of the Altiplano plateau. The subduction is oblique, leading to strike-slip faulting. Volcanic activity does not occur along the entire length of the Andes; where subduction is shallow, there are gaps with little volcanic activity. Between these gaps lie volcanic belts: the Northern Volcanic Zone, the Central Volcanic Zone, the Southern Volcanic Zone and the Austral Volcanic Zone.

There are about 400 Pliocene–Quaternary volcanoes in Peru, with Quaternary activity occurring only in the southern part of the country. Peruvian volcanoes are part of the Central Volcanic Zone. Volcanic activity in that zone has moved eastward since the Jurassic. Remnants of the older volcanism persist in the coastal Cordillera de la Costa but the present-day volcanic arc lies in the Andes, where it is defined by stratovolcanoes. Many Peruvian volcanoes are poorly studied because they are remote and difficult to access.

The basement underneath Huaynaputina is formed by almost sediments and volcanic intrusions of Paleozoic to Mesozoic age including the Yura Group, as well as the Cretaceous Matalaque Formation of volcanic origin – these are all units of rock that existed before the formation of Huaynaputina. During the Tertiary, these were overlaid by a total of deposits from the ignimbritic Capillune, Llallahui and Sencca Formations – all older rock units. Cretaceous sediments and Paleogene–Neogene volcanic rocks form the high plateau around Huaynaputina. The emplacement of the Capillune Formation continued into the earliest Pliocene; subsequently the Plio-Pleistocene Barroso Group was deposited. It includes the composite volcano that hosts Huaynaputina as well as ignimbrites that appear to come from calderas. One such caldera is located just south of Huaynaputina. The late Pleistocene to Holocene volcanoes have been classified as the Arequipa Volcanics.

Local

The vents of Huaynaputina trend from the north-northwest to the south-southeast, and this trend encompasses the neighbouring volcanoes Ubinas and Ticsani. Ubinas is a typical stratovolcano while Ticsani has a similar structure to Huaynaputina. These volcanoes constitute a volcanic field located behind the major volcanic arc, associated with faults at the margin of the Río Tambo g…