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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 10.98°N
  • 85.473°W

  • 1659 m
    5442 ft

  • 345010
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Orosi.

The Global Volcanism Program has no Weekly Reports available for Orosi.

The Global Volcanism Program has no Bulletin Reports available for Orosi.

Basic Data

Volcano Number

Last Known Eruption



Unknown - Evidence Uncertain

1659 m / 5442 ft


Volcano Types


Rock Types

Andesite / Basaltic Andesite
Basalt / Picro-Basalt

Tectonic Setting

Subduction zone
Continental crust (> 25 km)


Within 5 km
Within 10 km
Within 30 km
Within 100 km

Geological Summary

Orosí is one of a cluster of four eroded and vegetated cones in the Guanacaste Range at the NW corner of Costa Rica. Volcán Orosí itself has a conical shape as viewed from the north or west, but its flanks are heavily eroded. The complex includes Orosí, Orosilito, Volcán Pedregal, and Cacao. The highest peak of the volcanic complex is 1659-m-high Volcán Cacao, 5.5 km SE of Orosí. The summit of Cacao is cut by two large horseshoe-shaped calderas breached to the SW and east related to edifice collapse. The age of the latest activity of the complex is not known. Historical eruptions were reported from Orosí in 1844 and 1849, but even at the time of the first volcanological observations at the end of the 19th century, Orosí was overgrown with large trees, and the eruptions may actually have been from neighboring Rincón de la Vieja. The latest documented volcanic activity produced mudflows (perhaps secondary) about 3500 years ago.


The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Alvarado G E, 1989. Los Volcanes de Costa Rica. San Jose, Costa Rica: Universidad Estatal a Distancia, 175 p.

Alvarado G E, 2000. Volcanes de Costa Rica: su geologia, historia y riqueza natural. San Jose, Costa Rica: EUNED, 269 p.

Alvarado G E, Vega E, Chaves J, Vasquez M, 2004. Los grandes deslizamientos (volcanicos y no volcanicos) de tip debris avalanche en Costa Rica. Rev Geol Amer Central, 30: 83-99.

Alvarado-Induni G E, 2005. Costa Rica, Land of Volcanoes. San Jose, Costa Rica: EUNID, 306 p.

Barquero-H J, Saenz-R R, 1987. Aparatos volcanicos de Costa Rica. Heredia, Costa Rica: OVSICORI-UNA, 1:750,000 map and volcano list.

Carr M J, 1984. Symmetrical and segmented variation of physical and geochemical characterisitics of the Central American volcanic front. J Volc Geotherm Res, 20: 231-252. http://dx.doi.org/10.1016/0377-0273(84)90041-6

Cecchi E, van Wyk de Vries B, Lavest J-M, 2005. Flank spreading and collapse of weak-cored volcanoes. Bull Volc, 67: 72-91.

Chiesa S, Alvarado G E, Pecchio M, Corella M, Zanchi A, 1994. Contribution to petrological and stratigraphical understanding of the Cordillera de Guanacaste lava flows, Costa Rica. Rev Geol Amer Central, 17: 19-43.

Chiesa S, Bettoni M, Confortini F, Invernici N, Madesani R, Suardi M, 1996. Breva resena sobre la geologia de los Parques Nacionales Santa Rosa y Guanacaste. Rothschildia, 3(1): 1-5.

Chiesa S, Confortini F, Madesani R, 1998. Geologia del Area de Conservacion de Guanacaste. Rothschildia, 5(2): 1-36.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Kerle N, van Wyk de Vries B, 2001. The 1998 debris avalanche at Casita Volcano, Nicaragua; investigation of structural deformation as the cause of slope instability using remote sensing. J Volc Geotherm Res, 105: 49-63.

Mooser F, Meyer-Abich H, McBirney A R, 1958. Central America. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 6: 1-146.

Sapper K, 1925. The Volcanoes of Central America. Halle: Verlag Max Niemeyer, 144 p.

Siebert L, Alvarado G E, Vallance J W, van Wyk de Vries B, 2006. Large-volume volcanic edifice failures in Central America and associated hazards. In: Rose W I, Bluth G J S, Carr M J, Ewert J W, Patino L C, Vallance J W (eds), Volcanic hazards in Central America, {Geol Soc Amer Spec Pap}, 412: 1-26.

The Global Volcanism Program is not aware of any Holocene eruptions from Orosi. If this volcano has had large eruptions (VEI >= 4) prior to 10,000 years ago, information might be found on the Orosi page in the LaMEVE (Large Magnitude Explosive Volcanic Eruptions) database, a part of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.




Feature Name Feature Type Elevation Latitude Longitude
Cacao Stratovolcano 1659 m 10° 57' 7" N 85° 27' 4" W
Gongora Cone
Orosilito, Volcán Stratovolcano 1200 m
Pedregal Stratovolcano 1100 m

Photo Gallery

The highest peak of the Orosí volcanic complex is Volcán Cacao, which is seen in this view from the SW. The summit of Cacao, 5.5 km SE of Orosí, was breached to the SW as a result of edifice collapse. Orosí is one of a cluster of four eroded and vegetated cones in the Guanacaste Range at the NW corner of Costa Rica. Volcán Orosí itself has a conical shape as viewed from the north or west, but its flanks are heavily eroded. The age of the latest activity of the Orosí complex is not known.

Photo by Cindy Stine, 1989 (U.S. Geological Survey).
The SW side of Volcán Cacao, located at the SE end of the Orosí volcanic massif, is cut by an arcuate depression created during a massive slope failure in which the summit of the volcano was removed. The vertical light-colored stripes on the upper edifice are rockslide scars. The latest eruptive activity at the Orosí complex consisted of post-collapse lava domes and flows from Cerro Cacao.

Photo by Cindy Stine, 1989 (U.S. Geological Survey).
The Orosí volcanic complex is seen here from the north, with the summit of Orosí in the clouds at the right and Volcán Cacao, the highest peak of the complex, at the left. Orosí is one of a cluster of four eroded and vegetated cones in the eastern part of Guanacaste National Park at the NW corner of Costa Rica. Volcán Orosí itself has a conical shape as viewed from the north or west, but its flanks are heavily eroded. Reported eruptions of Orosí in 1844 and 1849 may actually have been from Rincón de la Vieja volcano.

Photo by William Melson (Smithsonian Institution).
The low hill in the background is part of a massive debris-avalanche deposit formed by collapse of Volcán Cacao (also called Cerro Cacao). The avalanche swept onto the flat-lying Pacific coastal plain as far as the Central American highway, near where this photo was taken.

Photo by Lee Siebert, 1998 (Smithsonian Institution).

Smithsonian Sample Collections Database

The following 31 samples associated with this volcano can be found in the Smithsonian's NMNH Department of Mineral Sciences collections. Catalog number links will open a window with more information.

Catalog Number Sample Description
NMNH 116066-1 Soil
NMNH 116066-10 Poorly-sorted pyroclastic-rock
NMNH 116066-11 Soil
NMNH 116066-12 Soil
NMNH 116066-13 Soil
NMNH 116066-14 Poorly-sorted pyroclastic-rock
NMNH 116066-15 Poorly-sorted pyroclastic-rock
NMNH 116066-16 Volcanic
NMNH 116066-17 Soil
NMNH 116066-18 Soil
NMNH 116066-19 Soil
NMNH 116066-2 Soil
NMNH 116066-20 Lahar
NMNH 116066-21 Poorly-sorted pyroclastic-rock
NMNH 116066-22 Fe-Mn oxides concretion
NMNH 116066-23 Andesite
NMNH 116066-24 Soil
NMNH 116066-25 Volcanic
NMNH 116066-26 Soil
NMNH 116066-27 Lahar
NMNH 116066-29 Fe-Mn oxides concretion
NMNH 116066-3 Poorly-sorted pyroclastic-rock with feldspar and quartz
NMNH 116066-31 Poorly-sorted pyroclastic-rock
NMNH 116066-32 Quartz and other crystals
NMNH 116066-349 Augite-hypersthene andesite
NMNH 116066-4 Soil
NMNH 116066-4 Soil
NMNH 116066-5 Tuff
NMNH 116066-6 Soil
NMNH 116066-7 Quartz
NMNH 116066-9 Soil

Affiliated Sites

Large Eruptions of Orosi Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
MODVOLC - HIGP MODIS Thermal Alert System Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.
MIROVA Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.