Report on Turrialba (Costa Rica) — September 1993
Bulletin of the Global Volcanism Network, vol. 18, no. 9 (September 1993)
Managing Editor: Edward Venzke.
Turrialba (Costa Rica) Regional earthquake causes visible cracks in crater area
Please cite this report as:
Global Volcanism Program, 1993. Report on Turrialba (Costa Rica). In: Venzke, E. (ed.), Bulletin of the Global Volcanism Network, 18:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199309-345070.
10.025°N, 83.767°W; summit elev. 3340 m
All times are local (unless otherwise noted)
Seismic station VTU, 0.5 km E of the main crater, recorded sporadic low-frequency microseismic activity in June-September. The number of events recorded ranged from 28 in June to 5 in July; specific values were not reported for August and September. An earthquake of M 5.0 took place on 10 July about 25.5 km to the SE. As a result of the earthquake, small cracks developed along the S margin of the central crater. Fumarolic activity continued from the N, NW, and SW walls of the main crater. On 13 July, fumarolic gases had a temperature of 90°C and a pH of 4.6. Temperature measurements in 1982 and 1985 show comparable values of 86°C and 85°C, respectively.
Geologic Background. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú 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. Fernández, J. Barquero, R. Van der Laat, F. de Obaldia, T. Marino, V. Barboza, and R. Sáenz, OVSICORI.