Report on Rincon de la Vieja (Costa Rica) — 20 May-26 May 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 20 May-26 May 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Rincon de la Vieja (Costa Rica). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 20 May-26 May 2020. Smithsonian Institution and US Geological Survey.
Rincon de la Vieja
10.83°N, 85.324°W; summit elev. 1916 m
All times are local (unless otherwise noted)
OVSICORI-UNA reported that periodic phreatic explosions at Rincón de la Vieja continued to be recorded by the seismic network and webcams during 20-26 May; most plumes rose no higher than 500 m above the crater rim. Some of the events were not visually confirmed by webcams because of weather conditions or darkness. A small ash eruption at 0537 on 21 May produced a plume that rose 1 km above the crater rim and contained less water vapor than plumes from eruptive events in the past weeks. Plumes from eruptive events at 1624 on 22 May and 0608 on 24 May rose 1 km above the rim. An event at 0325 on 25 May was heard by residents to the N but was no visually confirmed due to darkness. Later that day, in the early evening, an hour-long sequence of eruptions produced gas-and-steam plumes and ejected tephra no higher than the crater rim (except for an event at 1738).
Geologic Background. Rincón de la Vieja, the largest volcano in NW Costa Rica, is a remote volcanic complex in the Guanacaste Range. The volcano consists of an elongated, arcuate NW-SE-trending ridge that was constructed within the 15-km-wide early Pleistocene Guachipelín caldera, whose rim is exposed on the south side. Sometimes known as the "Colossus of Guanacaste," it has an estimated volume of 130 km3 and contains at least nine major eruptive centers. Activity has migrated to the SE, where the youngest-looking craters are located. The twin cone of 1916-m-high Santa María volcano, the highest peak of the complex, is located at the eastern end of a smaller, 5-km-wide caldera and has a 500-m-wide crater. A plinian eruption producing the 0.25 km3 Río Blanca tephra about 3500 years ago was the last major magmatic eruption. All subsequent eruptions, including numerous historical eruptions possibly dating back to the 16th century, have been from the prominent active crater containing a 500-m-wide acid lake located ENE of Von Seebach crater.