Report on Irazu (Costa Rica) — September 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 9 (September 1990)
Managing Editor: Lindsay McClelland.
Irazu (Costa Rica) Low-temperature fumarolic activity; small landslides
Please cite this report as:
Global Volcanism Program, 1990. Report on Irazu (Costa Rica). In: McClelland, L (ed.), Bulletin of the Global Volcanism Network, 15:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199009-345060.
9.979°N, 83.852°W; summit elev. 3432 m
All times are local (unless otherwise noted)
Low-temperature fumarolic activity (average temperature 90°C) continued. During July, there were small landslides down the wall separating the active crater and Diego de la Haya crater. An earthquake, centered 1 km NW of the active crater, occurred on 24 August.
Geologic Background. Irazú, one of Costa Rica's most active volcanoes, rises immediately E of the capital city of San José. The massive volcano covers an area of 500 km2 and is vegetated to within a few hundred meters of its broad flat-topped summit crater complex. At least 10 satellitic cones are located on its S flank. No lava flows have been identified since the eruption of the massive Cervantes lava flows from S-flank vents about 14,000 years ago, and all known Holocene eruptions have been explosive. The focus of eruptions at the summit crater complex has migrated to the W towards the historically active crater, which contains a small lake of variable size and color. Although eruptions may have occurred around the time of the Spanish conquest, the first well-documented historical eruption occurred in 1723, and frequent explosive eruptions have occurred since. Ashfall from the last major eruption during 1963-65 caused significant disruption to San José and surrounding areas.
Information Contacts: J. Barquero, OVSICORI.