Shortly after the [M 7.6] earthquake on 22 April [85 km WSW], numerous small concentric fractures were found along the S and SW rims of the central crater and the W rim of the main crater. Small landslides continued on the S, SW, and N walls of the main crater, and fumarole temperatures remained at 89°C.

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 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, V. Barboza, and J. Barquero, OVSICORI.