# Olca-Paruma
**Olca-Paruma** is a volcanic complex of overlapping stratovolcanoes forming a 15-km-long east-west ridge on the border between Chile and Bolivia, in the Central Andean Volcanic Arc of the Andes.[1](https://volcano.si.edu/volcano.cfm?vn=355050) The chain runs from the volcano Olca near its western end to Volcán Paruma at its eastern end, with Cerro Michincha flanking Olca on the west and the higher, pre-Holocene Cerro Paruma immediately east of Volcán Paruma.[1](https://volcano.si.edu/volcano.cfm?vn=355050) The complex is listed by the [Smithsonian Institution](https://www.edgepedia.org/smithsonian-institution)'s Global Volcanism Program (GVP) as Volcano Number 355050, with a summit elevation of 5,705 m (18,717 ft) at coordinates 20.939°S, 68.413°W.[1](https://volcano.si.edu/volcano.cfm?vn=355050) It sits in a subduction-zone setting on continental crust thicker than 25 km, and its major rock types are andesite, basaltic andesite, and dacite.[1](https://volcano.si.edu/volcano.cfm?vn=355050)
| Key fact | Detail |
|---|---|
| Location | Chile-Bolivia border, Central Andean Volcanic Arc; 40 km northwest of the town of Ollagüe, El Loa province, Chile[1](https://volcano.si.edu/volcano.cfm?vn=355050) • [2](https://www.sernageomin.cl/pdf/LIBROdevolcanes_SERNAGEOMIN.pdf) |
| Dimensions | 15-km-long E-W ridge of stratovolcanoes; volcanic products cover an area of ~80-2227 km², with an estimated main-edifice volume of 19-74 km³[1](https://volcano.si.edu/volcano.cfm?vn=355050) • [3](https://access.archive-ouverte.unige.ch/access/metadata/87700b05-d423-4947-b287-801e9b975220/download) |
| Summit elevation | 5,705 m (18,717 ft) per GVP; other compilations give 5450 m for the complex and 5407 m in SERNAGEOMIN's volcano file[1](https://volcano.si.edu/volcano.cfm?vn=355050) • [3](https://access.archive-ouverte.unige.ch/access/metadata/87700b05-d423-4947-b287-801e9b975220/download) • [4](https://www.sernageomin.cl/wp-content/uploads/2017/11/46_Olca-paruma.pdf) |
| Historical eruption | A flank eruption of unspecified character between 1865 and 1867, based on unconfirmed records; GVP lists 0 confirmed eruptive periods[1](https://volcano.si.edu/volcano.cfm?vn=355050) |
| Current activity | Persistent fumaroles, a 0.1 km² fumarolic field on Olca's summit, and frequent seismicity; small thermal anomaly hotspots in ASTER images[1](https://volcano.si.edu/volcano.cfm?vn=355050) • [5](https://catalogobiblioteca.sernageomin.cl/Archivos/15785_p_0974.pdf) • [3](https://access.archive-ouverte.unige.ch/access/metadata/87700b05-d423-4947-b287-801e9b975220/download) |
| Monitoring | Instrumented by OVDAS (SERNAGEOMIN) with a seismometer and surveillance camera; ranked 49th in the Chilean volcanic risk ranking[2](https://www.sernageomin.cl/pdf/LIBROdevolcanes_SERNAGEOMIN.pdf) • [3](https://access.archive-ouverte.unige.ch/access/metadata/87700b05-d423-4947-b287-801e9b975220/download) |
| Nearby population | 20 people within 5 km, 225 within 10 km, 2,318 within 30 km, and 16,180 within 100 km[1](https://volcano.si.edu/volcano.cfm?vn=355050) |
## Structure and composition
The complex is a chain of overlapping stratovolcanoes. A geological study by researchers at the Universidad Católica del Norte, presented at the E-ICES 12 meeting, identifies five main volcanoes from west to east: Michincha, Olca, Cumbre Blanca, Candelaria, and Paruma.[6](https://www.uncuyo.edu.ar/ices/upload/ices-xiiresumenes-final1.pdf) SERNAGEOMIN, Chile's National Geology and Mining Service, counts at least a dozen eruptive centers in the complex, with Olca and Paruma separated by about 9 km.[2](https://www.sernageomin.cl/pdf/LIBROdevolcanes_SERNAGEOMIN.pdf) The GVP catalog lists subsidiary cones including Cerro Michincha (5305 m), Cerro Olca Sur (5167 m), Cerro Paruma (5762 m), and Volcán Paruma (5728 m).[1](https://volcano.si.edu/volcano.cfm?vn=355050)
The chain grew in several phases. The Navas and colleagues study describes five evolutionary stages that formed nine emission centers, built from the Late Pliocene through the [Late Pleistocene](https://www.edgepedia.org/late-pleistocene) and Holocene on a Miocene volcanic basement.[5](https://catalogobiblioteca.sernageomin.cl/Archivos/15785_p_0974.pdf) The edifice activity developed during the Late Pleistocene to Holocene in twelve andesitic to dacitic units, and the rocks are high-potassium calc-alkaline lavas with silica contents between 52.55 and 69.31 percent by volume, ranging from basaltic andesites through andesites, trachyandesites, dacites, and rhyolites.[6](https://www.uncuyo.edu.ar/ices/upload/ices-xiiresumenes-final1.pdf) • [5](https://catalogobiblioteca.sernageomin.cl/Archivos/15785_p_0974.pdf)
Lava flows dominate the young surface. SERNAGEOMIN highlights a series of block lavas, some up to 8 km long, and the GVP notes andesitic-dacitic flows extending as far as 5 km north from Olca's active crater and to the north and west from vents farther west.[2](https://www.sernageomin.cl/pdf/LIBROdevolcanes_SERNAGEOMIN.pdf) • [1](https://volcano.si.edu/volcano.cfm?vn=355050) Volcán Paruma has been the source of conspicuous fresh lava flows, one of which extends 7 km southeast.[1](https://volcano.si.edu/volcano.cfm?vn=355050) Glaciation affected the complex strongly between 15,000 and 11,000 years ago, forming glacial cirques, U-shaped valleys, and extensive moraine deposits, which are frequent on the southern flank.[5](https://catalogobiblioteca.sernageomin.cl/Archivos/15785_p_0974.pdf) • [6](https://www.uncuyo.edu.ar/ices/upload/ices-xiiresumenes-final1.pdf)
## Eruptive history and current activity
The GVP records no confirmed eruptive periods for the complex. The only reported historical activity is a flank eruption of unspecified character between 1865 and 1867, which SERNAGEOMIN notes is based on unconfirmed records; the GVP entry classifies it as an uncertain eruption dated 1865 July 2 ± 182 days to 1867 July 2 ± 182 days.[1](https://volcano.si.edu/volcano.cfm?vn=355050)
Documented activity in the instrumental era has been fumarolic and seismic. On 13 November 1989, policemen from Ujina, 15 km southwest of Olca, described fumarolic activity accompanied by low-intensity seismicity, and in mid-March 1990 the state oil company (ENAP) geologist Patricio Sepulveda noted minor seismicity associated with Olca.[1](https://volcano.si.edu/volcano.cfm?vn=355050) The present fumarolic activity of Olca began within the last roughly 60 years, and the main fumarolic field is restricted to the dome within the summit crater; a geological survey places the active fumarolic field at 0.1 km² on Olca's summit.[3](https://access.archive-ouverte.unige.ch/access/metadata/87700b05-d423-4947-b287-801e9b975220/download) • [5](https://catalogobiblioteca.sernageomin.cl/Archivos/15785_p_0974.pdf) ASTER satellite images show small thermal anomaly hotspots.[3](https://access.archive-ouverte.unige.ch/access/metadata/87700b05-d423-4947-b287-801e9b975220/download)
Geophysical surveys have found little sign of deep unrest. A regional InSAR survey of Central Andean volcanoes detected no deformation at Olca-Paruma, and while no observed seismic unrest is on record, a seismological study identified three potential earthquake swarms in 2010; most other candidate swarms near Olca were ruled out as probably associated with mining.[3](https://access.archive-ouverte.unige.ch/access/metadata/87700b05-d423-4947-b287-801e9b975220/download)
## Hazards and monitoring
The complex is monitored by OVDAS, the Andean observatory arm of SERNAGEOMIN, and holds 49th place in the most recent version of the Chilean volcanic risk ranking.[3](https://access.archive-ouverte.unige.ch/access/metadata/87700b05-d423-4947-b287-801e9b975220/download) The SERNAGEOMIN volcano book lists a seismometer and a surveillance camera in its instrumental network, with no satellite positioning, tiltmeter, gas spectrometer, infrared camera, or infrasound microphone.[2](https://www.sernageomin.cl/pdf/LIBROdevolcanes_SERNAGEOMIN.pdf)
Hazard assessments describe the complex as having flank collapse potential but not the conditions to generate lahars.[3](https://access.archive-ouverte.unige.ch/access/metadata/87700b05-d423-4947-b287-801e9b975220/download) A reactivation would mainly involve the emission of andesitic to dacitic lavas together with low explosive activity, and could occur at any sector along the chain.[3](https://access.archive-ouverte.unige.ch/access/metadata/87700b05-d423-4947-b287-801e9b975220/download) • [4](https://www.sernageomin.cl/wp-content/uploads/2017/11/46_Olca-paruma.pdf) No villages stand close to the complex, but significant industrial activity linked to large-scale mining operates near its western flank.[4](https://www.sernageomin.cl/wp-content/uploads/2017/11/46_Olca-paruma.pdf) Exposure figures reflect the remote high-Andean setting: 20 people within 5 km and 16,180 within 100 km.[1](https://volcano.si.edu/volcano.cfm?vn=355050)
## Human use and setting
Sulfur deposits occur mainly around Volcán Olca, and the sulfur mines on the upper part of the complex were worked intensively until the mid-20th century.[2](https://www.sernageomin.cl/pdf/LIBROdevolcanes_SERNAGEOMIN.pdf) • [4](https://www.sernageomin.cl/wp-content/uploads/2017/11/46_Olca-paruma.pdf) A single obsidian sample from the volcano, catalog number NMNH 117456-16, is held in the Smithsonian's National Museum of Natural History mineral sciences collections.[1](https://volcano.si.edu/volcano.cfm?vn=355050)
## References
1. [Global Volcanism Program: Olca-Paruma (Volcano Number 355050), Smithsonian Institution](https://volcano.si.edu/volcano.cfm?vn=355050)
2. [SERNAGEOMIN, Volcanes de Chile: Complejo Volcánico Olca-Paruma](https://www.sernageomin.cl/pdf/LIBROdevolcanes_SERNAGEOMIN.pdf)
3. [Olca-Paruma country hazard profile, Global Volcanic Hazards and Risk / University of Geneva archive](https://access.archive-ouverte.unige.ch/access/metadata/87700b05-d423-4947-b287-801e9b975220/download)
4. [SERNAGEOMIN, Complejo volcánico Olca-Paruma (ficha regional)](https://www.sernageomin.cl/wp-content/uploads/2017/11/46_Olca-paruma.pdf)
5. [Navas, S. et al., Evolución geológica del Complejo Volcánico Olca-Paruma (CVOP), norte de Chile, VOLC-1, SERNAGEOMIN](https://catalogobiblioteca.sernageomin.cl/Archivos/15785_p_0974.pdf)
6. [Martínez, S., Navas, S., González, C., and Aguilera, F., Geología del Complejo Volcánico Olca-Paruma, norte de Chile, E-ICES 12](https://www.uncuyo.edu.ar/ices/upload/ices-xiiresumenes-final1.pdf)
---
*Topic: Encyclopedia › Physical world and mathematics › Earth sciences › Geology and mineralogy › Volcanology and seismology › Volcanoes and volcanic landforms › Volcanoes of the Andes*
*Initially written Oct 21, 2026 · Edited: Oct 25, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license