OVSICORI-UNA reported that incandescence from Turrialba’s West Crater was visible overnight during 15-16 January. Eruptive events were recorded at 2126 and 2132 on 17 January; the second event was stronger and produced an ash-and-gas plume that rose 1 km above the crater. Ashfall and a sulfur odor were reported by residents in Coronado, Tres Rios (30 km SW), Alajuela (50 km W), and Santa Ana (46 km WSW). At 1115 on 18 January an eruptive event produced a plume that rose 300 m and drifted SW.

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)