Casiri, also known as Paucarani, is an about 5,650 metres (18,537 ft) high complex volcano in the Barroso mountain range of the Andes, in the Tacna Region of Peru.

[8] Casiri is a 5,650 metres (18,540 ft) high[1] stratovolcano with lava domes[9] in the Palca district of Peru,[10] close to the border with Chile.

[12] Lava flows, stubby[11] and 50–100 metres (160–330 ft)[12] thick owing to viscosity,[16] originate on the younger edifice[13] and spread in several directions.

[34] Alterations in the reservoir that increased its storage volume[27] may be responsible for water leaks in the dam;[35] additional problems reported at Paucarani are contamination with heavy metals - especially arsenic.

[15] 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,[18] 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.

[38] A rain gauge of the Servicio Nacional de Meteorología e Hidrología del Perú [es] was in use on the volcano at 4,600 metres (15,100 ft) elevation from 1946 to 2003.

Of these, El Misti, Huaynaputina, Sabancaya, Ticsani, Tutupaca, Ubinas and Yucamane have been active during historical time.

[48] Holocene lavas sourced from fissure vents[49] overlie Pleistocene-age moraines and are uneroded;[50] radiometric dating on the volcano has yielded ages of 50,000 years[51] 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.

[52] There are no reported eruptions,[1] but activity may[53] or may not have occurred in historical time;[14] there are hot springs and solfataras[22] that are probably powered by Casiri's magmatic system.

[63] The Gloria sulfur mine lies on Casiri[45] – specifically, on the foot of Paucarani[64] 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.

[66] 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).