Casiri (Tacna)

The Rio Uchusuma, a tributary of the Rio Mauri, originates on Casiri.[19] A natural lake called Paucarani exists on the southeastern foot of Casiri,[16][20] and the Quebrada Achuco valley[9] is also located south of Casiri,[16] accompanied by wetlands.[22][16] On the other side, the southeastward-flowing Quebrada Mamuta lies to the north and northeast of the volcano, and to the northwest lie streams which flow through the lake Casiri and the lake Liñuma into the Rio Mauri.[5] Volcanic activity has influenced the drainages through the formation of lava dams, altering watersheds.[21]

An earth dam[20] on the Rio Uchusuma[23] was built in 1982-1986[24] and forms a reservoir also called Paucarani[22] on the southeastern foot of the volcano just southwest from the natural lake Paucarani.[16] This reservoir, which is run by the Junta de Usuarios del Valle de Tacna,[25] has a capacity of 10,500,000 cubic metres (370,000,000 cu ft) of water[26] and is a key[24] part of the water supply of Tacna;[27] water is transferred from the Paucarani reservoir through the Canal Uchusuma to Tacna,[28] covering 90% of Tacna's water consumption for both irrigation and human use.[29]

The Paucarani reservoir is also involved in the regulation of the Rio Caplina.[30] In 2012, a broken floodgate caused a damaging flood.[31] Alterations in the reservoir that increased its storage volume[24] may be responsible for water leaks in the dam;[32] additional problems reported at Paucarani are contamination with heavy metals - especially arsenic.[33]

Casiri is located in the Tarata Province[20] of the Tacna Region of Peru;[19] it lies about 100 kilometres (62 mi) northeast from the city of Tacna and close to the border with Chile and Bolivia.[13] The volcano is situated north of the town of Paucarani;[9] other human structures in the area south of Casiri are Calachata and Tulipiña. There are also numerous roads in the area,[16] including one which runs south of the volcano and reaches the Capaja camp to its west.[5] The town of Paucarani can be reached from the highway that connects Tacna with Charaña in Bolivia and Villa Industrial in Chile, through a secondary road.[34] The region is thinly populated.[35] A rain gauge of the Servicio Nacional de Meteorología e Hidrología del Perú was in use on the volcano at 4,600 metres (15,100 ft) elevation from 1946 to 2003.[36]

The volcano is considered a potential tourist attraction[37] owing to its scenery.[38] It is also part of the Monumento Natural de Paucarani geopark[20] and has been proposed to become a protected area.[38] The Paucarani reservoir also could be exploited for tourism purposes as well.[20]

Based on rock types that the Casiri volcano has erupted, it can be determined that it is composed of andesite, basaltic andesite and trachyandesite with a porphyric texture; the rocks contain biotite, hornblende, plagioclase and sanidine crystals.[9][21] Deposition of sulfur from gases has formed sulfur deposits.[42]

The Quaternary-age[43] Casiri is one of the youngest volcanic systems in southern Peru[9] with postglacial activity,[44] and Peru's southernmost Holocene volcano.[45] Holocene lavas sourced from fissure vents[46] overlie Pleistocene-age moraines and are uneroded;[47] radiometric dating on the volcano has yielded ages of 50,000 years[48] and surface exposure dating has found ages of 6,000 ± 900 and 2,600 ± 400 years for two dark lava flows southwest and south of Casiri's main summit, respectively.[49]

There are no reported eruptions,[1] but activity may[50] or may not have occurred in historical time;[12] there are hot springs and solfataras[20] that are probably powered by Casiri's magmatic system.[51] Casiri has been classified as a latent[52] or potentially active volcano[53] with a moderate threat level.[54] Earthquakes in 2020 and 2021 in the area do not appear to relate to volcanic activity.[55]

In 2012, the Geophysical Institute in Peru announced that it would begin monitoring Casiri, along with two other volcanoes in southern Peru, with seismometers.[56] They consider it a "low hazard" volcano.[57] As of 2021, there are two seismometers and one instrument measuring the deformation of the volcano at Casiri.[58] The installation of a network to detect deformation of the volcano is supposed to begin in 2022.[59]

The Gloria sulfur mine lies on Casiri[42] – specifically, on the foot of Paucarani[60] and southeast from the lava flows.[1] The sulfur is contained in heavily altered rocks covering an area of about 1 square kilometre (0.39 sq mi) and is genetically related to the activity of Casiri. It has been excavated through trenches and wells;[61] some installations could still be exploitable.[20] Another mine known as San Luis may also be associated with Paucarani;[61] it is located on the northwestern flank.[45][5] Precious metals might occur in the hydrothermally altered areas at Casiri.[62]

The area of Casiri features the Chungará-Kallapuma geothermal field, where about 50 separate vents occur along the path of the Quebrada Chungará and the Kallapuma River; they reach temperatures of 83.4 °C (182.1 °F). These phenomena appear to relate to the activity of neighbouring volcanoes, which supply the heat to the geothermal field,[63] while rainfall supplies the water and faults the paths for the ascending water; the hot springs are currently used as spas by the local population.[64]

The geothermal power potential of the Tacna Region has been researched, partly because the Tacna Region covers its electricity demand with either nonrenewable oil or with hydropower (which is subject to climate variations). Mining is both an important economic resource in Tacna and a major consumer of electricity.[65] In the case of the Chungará-Kallapuma geothermal field, the capacity of a 75 megawatt power plant exists;[66] however, despite ongoing research since 1974 and a high geothermal potential, no geothermal power production has taken place in Peru as of 2013.[41]