OVSICORI-UNA reported that a point of incandescence on the SW wall of Turrialba’s Cráter Oeste was visible on 23 February and was coincident with the area of strongest gas emissions. At 1955 on 27 February an eruption produced a diffuse ash plume that rose 300 m above the summit and drifted NE. Rumbling heard on 28 February was sometimes coincident with minor ash emissions.

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.

Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)