Sairecabur

Sairecabur (Spanish pronunciation: [sajɾekaˈβuɾ]) is a volcano located on the frontier between Bolivia and Chile. It is part of the Andean Central Volcanic Zone. Sairecabur proper is 5,971 m (19,590 ft) high; other mountains in the range are 5,722 m (18,773 ft) high Curiquinca, 5,819 m (19,091 ft) high Escalante and 5,748 m (18,858 ft) high Cerro Colorado, all of which have erupted a number of lava flows. Also in close proximity to Sairecabur lie the volcanic centres Licancabur, Putana and Juriques.

Sairecabur proper is accompanied by a 4.5 km (2.8 mi) wide caldera. Before the formation of this caldera the volcano may have been 7,000 m (23,000 ft) high and thus one of the highest volcanoes on Earth. After the formation of this caldera lava effusion occurred during the Pleistocene and Holocene; there is no reported historical activity, however. Eruption products on Escalante and Sairecabur include andesite and dacite. The climate is dry, cold and very sunny.

An Inca sanctuary has been found on Sairecabur, and sulfur mines exist in the mountain chain. More recently, the Receiver Lab Telescope was installed on the volcano. It is the highest submillimeter telescope in the world at an altitude of 5,525 m (18,127 ft).

West of South America, the Nazca Plate subducts beneath the South America Plate. This process has formed the Andean Volcanic Belt, which is subdivided into the Northern Volcanic Zone, the Central Volcanic Zone and the Southern Volcanic Zone. These belts have different underlying crusts and thus have different typical magma compositions. These volcanic zones are separated from each other by zones where there is no volcanism, associated with a shallow dip of the seismic zone of the subducting plate.

Sairecabur is part of the Andean Central Volcanic Zone (CVZ). A number of stratovolcanoes can be found in the area, many of which were affected by explosive eruptions that have destroyed parts of their edifices. Effusion of large amounts of lava took place from several cones. Many volcanoes are extinct and only a few have documented activity. The geologist Juan Brüggen in 1950 estimated that there were about 800 volcanoes in northern Chile, about 37 of them east of the Salar de Atacama. Also part of the volcanism are large ignimbrites, which are usually thought to be of Miocene age. Those in the area of Sairecabur often originated in the neighbourhood to the conical volcanoes. The volcanoes formed over crust with thicknesses reaching 70 km (43 mi), thus the erupted magmas are heavily influenced by the crust. A number of the highest stratovolcanoes in the world are in the CVZ. Historical activity has been low in comparison to the volcanic zones of southern Chile and Colombia/Ecuador. In Chile, much of the area of the CVZ is desert and thus difficult to research.

Sairecabur is constructed on the two Pliocene-Pleistocene Puripicar and Chaxas formations. Some lavas from Sairecabur have also overrun the Purico formation, which is of Pleistocene age and includes ignimbrites from the Purico Complex. The basement beneath Sairecabur and Licancabur contains a large number of faults.

Sairecabur is located at a distance of 25 kilometres (16 mi) from San Pedro de Atacama. The volcano saddles the frontier between Bolivia and Chile, where it lies in the Antofagasta Region. Laguna Verde lake, Licancabur volcano and Portezuelo de Chaxas pass lie south of Sairecabur. East of the Sairecabur range lie Mount Nelly and Cerro Laguna Verde.

The Treaty of Peace and Friendship (1904) traced the frontier between Bolivia and Chile along the Sairecabur chain. Disagreements between the topographic maps in the two countries mean that the naming of the mountains is often confusing. Escalante is also known as Apagado.