Report on Irazu (Costa Rica) — 8 July-14 July 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 8 July-14 July 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, 8 July-14 July 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 at 2138 on 12 July the seismic network at Irazú recorded a significant landslide, possibly in the N part of the crater. The event could not be confirmed because of weather conditions. Another landslide event was recorded at 1538 on 13 July, which again could not be visually confirmed.
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.