Olca-Paruma is a volcanic complex in Chile. Lying on the border between Chile and Bolivia, it is formed by an east–west alignment of volcanoes. From west to east, these are Cerro Paruma, Volcan Paruma, Olca, and Mencheca or Michincha. Aside from the mines of Ujina, Rosario, and Quebrada Blanca, the area is sparsely populated.

These volcanoes have erupted mainly lava flows, which descend their slopes. The volcanoes range in shape from long and narrow to short and stubby. Craters are found on the volcanoes. Eruptive activity commenced during the Pleistocene and continued during the Holocene. There is evidence of glaciation on the volcanoes, including moraines.

The only historical activity of unspecified character occurred during 1865–1867; the volcano may still be a threat to Bolivia and Chile. It also features vigorous fumarolic activity and has been inspected for its geothermal energy potential.

Olca-Paruma forms part of the Chile-Bolivia border. The Chilean sector lies partly in the commune of Ollagüe, El Loa province, Antofagasta Region, and partly in the Tamarugal Province, Tarapaca Region. The Bolivian segment lies in the Potosi Department. The Estación Yuma and the Estación Ruquíos lie at the southern foot of Olca-Paruma, along with an unpaved road. The buildings of Cercicha and Pajancha lie on the Bolivian side, at the southeastern foot.

Southwest of Olca-Paruma lie various mines, including, in order of increasing distance: Ujina, Rosario, and Quebrada Blanca. Habitations in the area include Amincha, Collahuasi, Cosca, and Ollagüe. Olca-Paruma is relatively remote from human habitation. During the 20th century, sulfur mining operations connected to Ollagüe took place at Olca.

Olca-Paruma belongs to the Central Volcanic Zone (CVZ) of the Andean Volcanic Belt, a 1,500 kilometres (930 mi) long volcanic arc that features 44 active, or potentially active, volcanoes. The most active volcano is Lascar, where a major eruption took place in 1993. Other volcanoes with recorded activity include Irruputuncu, Isluga, and San Pedro. Fumarolic activity has been recorded at Alitar, Guallatiri, Lastarria, Olca-Paruma, Ollagüe, Putana, and Tacora. The volcanic activity of the CVZ ultimately is caused by the Nazca Plate subducting beneath the South American Plate.

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Olca-Paruma is a 20-kilometre (12 mi) long volcanic complex. It is composed of the 5,762-metre (18,904 ft) high conical Cerro Paruma (20°56′S 68°26′W / 20.933°S 68.433°W / -20.933; -68.433), the 5,728-metre (18,793 ft) high Volcan Paruma (20°57′S 68°26′W / 20.950°S 68.433°W / -20.950; -68.433), 2 kilometres (1.2 mi) west of Cerro Paruma, the 5,705-metre (18,717 ft) high Olca (20°56′20″S 68°24′47″W / 20.939°S 68.413°W / -20.939; -68.413), 7 kilometres (4.3 mi) west of Volcan Paruma, and the 5,305-metre (17,405 ft) high Mencheca (20°56′S 68°30′W / 20.933°S 68.500°W / -20.933; -68.500) volcanoes, which are aligned in an east–west direction. Mencheca is also known as Michincha. Additional centres are the 5,167-metre (16,952 ft) high Cerro Olca Sur (20°58′S 68°29′W / 20.967°S 68.483°W / -20.967; -68.483) and Cumbre Blanca. Directly west of Cerro Paruma lies Cerro Candelaria and north of it a saddle named Salle Orca, which leads north to another summit, Cerro Moro. Olca has a summit crater, and two craters are found on Volcan Paruma, plus at least twelve additional vents. Some vents have well-preserved craters and others are eroded. The volcanoes are accompanied by surge deposits formed during explosive activity. The basal diameter of the edifice is 17 kilometres (11 mi), the basal surface 227 square kilometres (88 sq mi), and the volume of the edifice is 74 cubic kilometres (18 cu mi).