Report on Rincon de la Vieja (Costa Rica) — October 1994
Bulletin of the Global Volcanism Network, vol. 19, no. 10 (October 1994)
Managing Editor: Richard Wunderman.
Rincon de la Vieja (Costa Rica) Thirty-one small high-frequency events
Please cite this report as:
Global Volcanism Program, 1994. Report on Rincon de la Vieja (Costa Rica) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 19:10. Smithsonian Institution.
Rincon de la Vieja
10.83°N, 85.324°W; summit elev. 1916 m
All times are local (unless otherwise noted)
Seismic station RIN (5 km W of the active crater) received 31 events of high-frequency. The events were only detected locally, they had Richter magnitudes of less than 1, and S minus P times of less than 2 seconds. For comparison, during April, the local seismic station received only 13 low-frequency events. In contrast, there were 283 low-frequency events during the previous month, the most reported so far this year.
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.
Information Contacts: E. Fernández, J. Barquero, and V. Barboza, OVSICORI.