OVSICORI-UNA reported that during 6-11 November low-level ash-and-gas emissions at Turrialba were continuous, though occasionally punctuated by energetic explosions which elevated the plumes as high as 500 m above the crater rim. The emission drifted towards the Valle Central. Ashfall was reported in several areas downwind including Cascajal de Coronado, Desamparados (35 km WSW), San Antonio, Guadalupe (32 km WSW), Sabanilla, San Pedro Montes de Oca, Moravia (31 km WSW), Heredia (38 km W), and Coronado (San José, 35 km WSW). Emissions likely continued on 12 November, though inclement weather did not allow for visual confirmation.

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)