Irazu Volcano

Updated: Nov 12, 2025 10:02 GMT - refresh

Stratovolcano

Costa Rica, 9.98°N / -83.85°W

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Summit height: 3432 m / 11,260 ft

Current status: normal or dormant (1 out of 5)

Last update: 22 Dec 2021 (Smithsonian / USGS Weekly Volcanic Activity Report)

Irazú (3432 m) immediately east of the capital San José is Costa Rica's highest and one of its most active volcanoes. Tephra fall (ash) during the last major eruption of Irazú in 1963-65 caused heavy damage to infrastructure and life in San José and its surroundings.

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Typical eruption style: Explosive.
Irazu volcano eruptions: 1726, 1775(?), 1821(?), 1822, 1823, 1826(?), 1842, 1844(?), 1847, 1864, 1875, 1882(?), 1909(?), 1914(?), 1917-21, 1924, 1928, 1930, 1933, 1939-40, 1963-65, 1977, 1994

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Background

Irazú is a massive stratovolcano covering more than 500 sq km with at least 10 flank cones on the southern flank, all being older than at least 14,000 years when a massive lava flow (the "Ceravantes" flow) was erupted.
All known eruptions from Irazú during the past 10,000 years have been explosive and originated from the summit craters that show a migration to the W over time. The historically active crater contains a small acid lake of changing size and color.
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Source: GVP, Smithsonian Institution

Irazu Volcano Photos

The lake-filled crater of Irazu volcano, Costa Rica (Photo: Tom Pfeiffer)

Laguna del Irazu Volcano, Costa Rica (Photo: WNomad)

Crater El Piroclastico of Irazu Volcano near Cartago, Costa Rica (Photo: WNomad)

Crater Principal of Irazu Volcano, near Cartago, Costa Rica (Photo: WNomad)

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Significant volcanic eruptions: Irazu volcano

In the past 10,000 years, Irazu has had at least 24 confirmed volcanic eruptions, out of which 19 are documented by historical records, while the others can be inferred from geological evidence.
Additionally, there are 15 uncertain or discredited eruptions from Irazu volcano.

The table below lists all known eruptions (date in bold face) of Irazu volcano since around 1800. Updates on the most recent volcanic activity of Irazu can be found on the news page of Irazu volcano.

Date	Note	VEI	Deaths	Damage
2019 May 2 (eruptive episode 2019 May 2)	Tsunami recorded Historical obs./docs.	0			Info
2019 May 2: No eruption. Reference #13833 states: that on May 2, 2019 (12:53 p.m.) a landslide with a seiche (type tsunami; in a lake) occurred, which produced a change in the color of the waters of the crater lake, a product of the landslide and sediment input, as well as the disturbance of the lacustrine bottom Cited references #13833 Alvarado, G.E., Campos Duran, D., Brenes Andre, J., Alpizar, Y., Nunez, S., Esquivel, L., Sibaja, J.P., and Fallas, B. (2021): Peligros Volcanicos Del Irazu, Costa Rica. Comision Nacional de Prevencion de Riesgos y Atencion de Emergencias (CNE). December 2021. Source: NOAA National Centers for Environmental Information (NCEI), Global Significant Earthquake Database. doi:10.7289/V5TD9V7K
?? 1994 Dec 8	Uncertain Eruption Historical obs./docs.	2
1977 Mar 3	Historical obs./docs.	1
1974 Mar 2 - Mar 7	Discredited Eruption
1967 Aug 7	Discredited Eruption
1963 Mar 13 - 1965 Feb 13	Historical obs./docs.	3
1963 Dec 10 (eruption 1963 Mar 13 - 1965 Feb 13)	Historical obs./docs.	3	40	moderate	Info
1963 Dec 10: Waldron gives number killed in mudflows as >20. Other estimates range from "only a few" to 30. 2 killed and 10 injured by a shower of ash and stones on the crater rim in mid-April. 5 died and many wounded in April and Aug 1964. Stine and Banks report that mudflows killing 20 persons and destroying many structures along the Rio Chiquito were secondary. Over a 2-year period 46 mudflows occurred along the Rio Reventado valley; one killed at least 20 persons and destroyed 400 houses and some factories. (reference #9675) Cited references #1412 Simkin, Tom, and Lee Siebert with the collaboration of Russell Blong, Jonathan Dehn, Christopher Newhall, Roland Pool, and Thomas C. Stein (1994): Volcanoes of the World, Second Edition, A Regional Directory, Gazetteer, and Chronology of Volcanism During the Last 10,000 Years, Geoscience Press, Inc., Tucson, Arizona, in association with Smithsonian Institution, Global Volcanism Program, Washington, D.C., p. 164-176. #1671 Stine Cynthia M. and Norman G. Banks (1991): Costa Rica Volcano Profile. U.S. Geological Survey Open-File Report, 67 p. #9675 Siebert, Lee, Tom Simkin, Paul Kimberly (2010): Fatalities & Evacuations, Volcanoes of the World, Third Edition, Geoscience Press, Inc., University of California Press, Smithsonian Institution, Washington, D.C., p. 329-347. Source: NOAA National Centers for Environmental Information (NCEI), Global Significant Earthquake Database. doi:10.7289/V5TD9V7K
1963 Mar 17 (eruption 1963 Mar 13 - 1965 Feb 13)	Historical obs./docs.	3	15		Info
1963 Mar 17: Witham lists 15 fatalities, with range of 5-15. (reference #9675) Cited references #9675 Siebert, Lee, Tom Simkin, Paul Kimberly (2010): Fatalities & Evacuations, Volcanoes of the World, Third Edition, Geoscience Press, Inc., University of California Press, Smithsonian Institution, Washington, D.C., p. 329-347. Source: NOAA National Centers for Environmental Information (NCEI), Global Significant Earthquake Database. doi:10.7289/V5TD9V7K
1962 Aug 9	Discredited Eruption
1939 May 18 - 1940 Feb	Historical obs./docs.	2
1933 Mar 22 ? - Jul 25	Historical obs./docs.	2
1930 Oct	Historical obs./docs.	2
1928 Feb 14 - May 26 ±5 d.	Historical obs./docs.	2
1924 Mar - Apr	Historical obs./docs.	2
1917 Sep 27 - 1921	Historical obs./docs.	3
?? 1914 Feb 21	Uncertain Eruption	?
1910	Discredited Eruption
?? 1909	Uncertain Eruption	2
1899	Discredited Eruption
1894	Discredited Eruption
1889 Feb 28	Discredited Eruption
1886	Historical obs./docs.	2?
1885	Historical obs./docs.	2?
1883 Jan 3	Discredited Eruption
?? 1882	Uncertain Eruption	2
1875 ±5 y.	Historical obs./docs.	2
1864 Sep 16 - Sep 17	Historical obs./docs.	2
1847 May 18	Historical obs./docs.	2
?? 1844 May	Uncertain Eruption	2
1842	Historical obs./docs.	2
?? 1826	Uncertain Eruption	?
1823	Historical obs./docs.	2?
1822 May 7	Historical obs./docs.	2
?? 1821 May	Uncertain Eruption	2

Remark:

Our list of volcanic eruptions closely follows the database of eruptions of the Smithsonian's Global Volcanism Project (GVP), the internationally most recognized data source for volcanic eruptions, but also includes significant eruptive episodes or related volcano events. "Volcanic eruptions" are usually to be understood as sequences of individual eruptive episodes that can follow each other, or even overlap (if several vents are involved), and can last many years, decades or even longer. For example, the current activity of Stromboli volcano is understood as a single eruption that has been ongoing since 1934.

Sources: NOAA National Centers for Environmental Information (NCEI), Global Significant Volcanic Eruptions Database. doi:10.7289/V5TD9V7K | Global Volcanism Project / Smithsonian Institution

Irazu Volcano FAQ

+When was the last eruption of Irazu volcano?

The last confirmed eruption of Irazu occurred in 1977.

+How often does Irazu volcano erupt?

Since 1723, Irazu volcano has had at least 19 historically documented eruptions. This means that it erupts on average every 15.9 years.
Many eruptions of Irazu have lasted more than one year. In total, the volcano has been in eruption during 27 out of 302 years until now. In other words, Irazu has been active at least one in 11.2 years on average. Note that this value is likely an underestimate, because the known history of eruptions from Irazu is likely incomplete, especially further back in time.

+How active is Irazu volcano at present?

Irazu volcano is relatively active: Since 1900, it has had 15 eruptions, and been active during 15 years out of 126 as of now. This means, Irazu has been in eruption one in 8.4 years on average. The last eruption was in 1977 and ended 49 years ago.

+When was the largest eruption of Irazu volcano?

The largest eruption of Irazu volcano in historic times occurred during 1963 - 1965. It ranks as a "vulcanian" eruption with a magnitude 3 on the VEI (Volcanic Explosivity Index) scale.

Latest satellite images

See also: Sentinel hub | Landsat 8 | NASA FIRMS

Latest satellite images

Irazu Volcano Maps

Below is a selection of maps showing the location and surroundings of the volcano at various resolutions based on aerial-imagery / terrain maps. Feel free to use them for non-commercial purposes on your blog or website as long as you credit them with a link back to this page (click to copy it).