Report on Irazu (Costa Rica) — 22 April-28 April 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 April-28 April 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Irazu (Costa Rica). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 April-28 April 2020. Smithsonian Institution and US Geological Survey.
9.979°N, 83.852°W; summit elev. 3432 m
All times are local (unless otherwise noted)
OVSICORI-UNA reported that on 21 April scientists confirmed that the lake in Irazú’s crater was gone and noted continuous intra-crater landslides from unstable parts of the crater.
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.