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Report on Rincon de la Vieja (Costa Rica) — July 2008

Rincon de la Vieja

Bulletin of the Global Volcanism Network, vol. 33, no. 7 (July 2008)
Managing Editor: Richard Wunderman.

Rincon de la Vieja (Costa Rica) Tremor durations from minutes to over an hour during June-April 2008

Please cite this report as:

Global Volcanism Program, 2008. Report on Rincon de la Vieja (Costa Rica) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 33:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200807-345020

Rincon de la Vieja

Costa Rica

10.83°N, 85.324°W; summit elev. 1916 m

All times are local (unless otherwise noted)

Activity at Rincón de la Vieja was last reviewed in May 2007 (BGVN 32:10), when low-level fumarolic activity was noted. During June 2007, the seismographic station 5 km to the SW of the crater registered seven low-frequency earthquakes and three low-frequency tremors. The first tremor occurred on 12 June and lasted 2 hours and eight minutes; the second and third occurred on 27 and 28 June and they lasted 37 minutes and 38 minutes, respectively.

The July earthquake activity was consistent with June; 6 low frequency quakes were recorded. Again, tremor activity occurred on 28 and 29 July, the first lasted 35 minutes and the second lasted 17 minutes. Little activity was noted during August and September, and October activity consisted only of tremors. On 23 October, the tremor lasted 37 minutes, and on 24 October it lasted 25 minutes.

No significant seismicity was recorded during the first three weeks of November. The seismic recording instrument went out of service from 22 November through December and January.

During February, 2008, 44 low-frequency earthquakes were registered in two groups; the first on 6 and 7 February and the second between 17 and 23 February.

Technical difficulties in March precluded a complete record of seismic activity; however, when recording was available, 116 low frequency earthquakes were noted.

Technical problems persisted in April, however during the first part of the month there was a low-frequency earthquake and 1.16 hours of tremor. Two deep earthquakes were also noted; the first registering M 3.5 at a depth of 11 km and the second M 2.9 at a 25 km depth.

Geological Summary. 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 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 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 3,500 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, E. Duarte, R. Van der Laat, M. Martinez, W. Sáenz, V. Barboza, Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA), Apartado 86-3000, Heredia, Costa Rica (URL: http://www.ovsicori.una.ac.cr/).