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Report on Turrialba (Costa Rica) — May 1997


Bulletin of the Global Volcanism Network, vol. 22, no. 5 (May 1997)
Managing Editor: Richard Wunderman.

Turrialba (Costa Rica) Fumarolic temperatures near 90°C; two M 2 earthquakes in May

Please cite this report as:

Global Volcanism Program, 1997. Report on Turrialba (Costa Rica) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 22:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199705-345070


Costa Rica

10.025°N, 83.767°W; summit elev. 3340 m

All times are local (unless otherwise noted)

Fumaroles emitted comparatively little gas but remained active in the main crater's NE, N, NW, and W parts, with temperatures in the range 89-90°C. In the N and S parts of the crater, small areas of mass-wasting covered some fumaroles. Seismicity at a station 500 m E of the active crater (station VTU) has been measured consistently since May 1996; reported local earthquake counts included 72 in December 1996, 146 in January 1997, 194 in February, 182 in March, and 137 in April. During May, seismic station VTU registered a total of 72 earthquakes. On 10-11 May, four of these were located at 5-6 km depths at 8-9 km distances NE of the crater, with magnitudes of 2.1-2.6. Their origin was possibly related to a local fault.

Geological Summary. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of IrazĂș volcano overlooking the city of Cartago. The massive edifice covers an area of 500 km2. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.

Information Contacts: E. Fernandez, R. Van der Laat, F. de Obaldia, T. Marino, V. Barboza, W. Jimenez, R. Saenz, E. Duarte, M. Martinez, E. Hernandez, and F. Vega, Observatorio Vulcanologico y Sismologico de Costa Rica, Universidad Nacional (OVSICORI-UNA), Apartado 86-3000, Heredia, Costa Rica.