Report on Rincon de la Vieja (Costa Rica) — December 1994
Bulletin of the Global Volcanism Network, vol. 19, no. 12 (December 1994)
Managing Editor: Richard Wunderman.
Rincon de la Vieja (Costa Rica) Minor seismicity
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, 19:12. Smithsonian Institution.
Rincon de la Vieja
10.83°N, 85.324°W; summit elev. 1916 m
All times are local (unless otherwise noted)
During December 1994, Rincón de la Vieja was seismically active. The local station (5 km SW of the active crater) registered three small-amplitude events on 19 December and, at 2121, a fourth of Richter magnitude 3.0. The last event had a focal depth of 23 km and an epicenter 4.5 km NE of the active crater. One event took place each day on 23, 24, and 25 December; these events each had an S -P delay in the range of 1.9 to 2.5 seconds.
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: OVSICORI.