Report on Irazu (Costa Rica) — July 1989
Scientific Event Alert Network Bulletin, vol. 14, no. 7 (July 1989)
Managing Editor: Lindsay McClelland.
Irazu (Costa Rica) Solfataric activity
Please cite this report as:
Global Volcanism Program, 1989. Report on Irazu (Costa Rica) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 14:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198907-345060.
9.979°N, 83.852°W; summit elev. 3432 m
All times are local (unless otherwise noted)
During fieldwork in June, Irazú remained quiet. Activity was limited to low-temperature solfataras on the NW flank. There was a small emerald green lake in the main crater, active in the 1963-65 explosive eruption.
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: G. Soto, Escuela Centroamericana de Geologia & Red Sismologica Nacional, Univ de Costa Rica.