OVSICORI-UNA reported that fieldwork on 23 September revealed severely impacted vegetation on Turrialba's flanks and inner caldera in areas only mildly affected during the previous three years of sustained degassing. Vegetation in the S and SE summit areas was severely burned and infrastructure was impacted during August and September. Along the flank, S of the W crater, plants were burned down to the soil. Trees in lower-altitude areas were yellowed and seared due to extreme acidification. Pastures and areas along canyons and depressions were also affected. OVSICORI-UNA recommended that precautions should be taken when carrying out activities in the affected areas.

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)