Parinacota (in Hispanicized spelling), Parina Quta or Parinaquta is a dormant stratovolcano on the border of Bolivia and Chile. Together with Pomerape it forms the Nevados de Payachata volcanic chain. Part of the Central Volcanic Zone of the Andes, its summit reaches an elevation of 6,380 metres (20,930 ft) above sea level. The symmetrical cone is capped by a summit crater with widths of 1 kilometre (0.62 mi) or 1,000 metres (3,300 ft). Farther down on the southern slopes lie three parasitic centres known as the Ajata cones. These cones have generated lava flows. The volcano overlies a platform formed by lava domes and andesitic lava flows. The volcano started growing during the Pleistocene and formed a large cone. At some point between the Pleistocene and the Holocene, the western flank of the volcano collapsed, generating a giant landslide that spread west and formed a large, hummocky landslide deposit. The avalanche crossed and dammed a previously existing drainage, impounding or enlarging Lake Chungará; numerous other lakes now forming the headwaters of the Rio Lauca sprang up within the deposit. Volcanic activity rebuilt the cone after the collapse, cancelling out the collapse scar. Parinacota had numerous effusive and explosive eruptions during the Holocene, the latest about 200 years ago. While there are no recorded eruptions, legends of the local Aymara people imply that they may have witnessed one eruption. Renewed activity at Parinacota is possible in the future, although the relatively low population density in the region would limit potential damage. Some towns and a regional highway between Bolivia and Chile are potentially exposed to the effects of a new eruption.
Name The name "Parinacota" is Aymara. Parina means flamingo and quta lake. Parinacota and its neighbour Pomerape are also known as the Nevados de Payachata, "twins". This refers to the fact that the volcanoes resemble each other.
Geomorphology and geology Parinacota lies in the Altiplano, a high plateau in the Central Andes. The border between Bolivia and Chile bisects the volcano and runs along the rim of the crater, which lies in Bolivia. In Chile, where most of the edifice is located, Parinacota lies in the commune of Putre, Arica y Parinacota Region, and in Bolivia in the Oruro Department of the Sajama Province. The towns of Ajata and Parinacota lie southwest and west of the volcano, respectively. The region lies at high altitude and access is difficult, hampering research on the volcanoes of the Central Andes.
Regional
The Nazca Plate and Antarctic Plate subduct beneath the South America Plate in the Peru-Chile Trench at a pace of 7–9 centimetres per year (2.8–3.5 in/year) and 2 centimetres per year (0.79 in/year), respectively, resulting in volcanic activity in the Andes. Present-day volcanism occurs within four discrete belts: The Northern Volcanic Zone (NVZ), the Central Volcanic Zone (CVZ), the Southern Volcanic Zone (SVZ) and the Austral Volcanic Zone (AVZ). These extend between 2°N-5°S, 16°S-28°S, 33°S-46°S and 49°S-55°S, respectively. Between them they contain about 60 active volcanoes and 118 volcanoes which appear to have been active during the Holocene, not including potentially active very large silicic volcanic systems or very small monogenetic ones. These belts of active volcanism occur where the Nazca Plate subducts beneath the South America Plate at a steep angle, while in the volcanically inactive gaps between them the subduction is much shallower; thus there is no asthenosphere between the slab of the subducting plate and the overriding plate in the gaps. Parinacota is part of the CVZ, which contains about 44 active volcanoes. Most volcanoes of the CVZ are relatively poorly researched and many exceed 5,000 metres (16,000 ft) of elevation. Some of these edifices were active during historical time; these include El Misti, Lascar, San Pedro and Ubinas; the largest historical eruption of the CVZ occurred in 1600 at Huaynaputina. Other volcanoes in the CVZ that have been the subject of research are Galan and Purico complex. The CVZ has a characteristically thick crust (50–70 kilometres (31–43 mi)) and the volcanic rocks have peculiar oxygen and strontium isotope ratios in comparison to the SVZ and NVZ. Parinacota lies in a segment of the CVZ where the Peru-Chile Trench undergoes a 45° curvature, and where the direction of subduction changes from diagonal to perpendicular. The crust is especially thick there, the reasons for this are not agreed upon yet and may vary between the western and eastern sides of the CVZ. Subduction-related volcanism in the region has been ongoing since 200 million years ago, burying most of the Precambrian basement. Various units of sedimentary and volcanic origin form most of the outcropping basement in the region. A dramatic increment of volcanic activity occurred approximately 27 million years ago, when the Farallon Plate broke apart and subduction increased substantially. On the Chilean side, the basement is formed by the Oligocene-Miocene Lupica formation, the Miocene Ajoya volcanics, the Lauca formation and the Lauca Ignimbrite. On the Bolivian side the oldest volcanites are the Oligocene Kollukollu formation 34 million years ago and the 23 million years old Rondal Lavas. Miocene volcanic activity generated the Berenguela, Carangas and Mauri formations, followed by the Perez formation during the Pliocene and Pleistocene. These formations were all affected by terrain uplift and folding, probably linked to changes in the subduction regime. Volcanism continued into the late Pleistocene and Holocene (Condoriri 650,000±70,000 and Pomerape between 300,000-100,000 years ago), and was accompanied by glacial activity during the Pleistocene. During this whole time period, volcanic activity progressively migrated westward; presently, it is located on the Bolivia-Chile border.
Local
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