Based on webcam views, weather models, and OVSICORI-UNA updates, the Washington VAAC reported that on 8 March diffuse ash emissions rose from Turrialba's West Crater and seismicity increased. OVSICORI-UNA reported an ash emission at 0100 on 11 March. Another ash emission occurred at 1050 on 12 March. Almost continuous ash emissions were observed in the afternoon and were punctuated by two noticeable explosions at 1338 and 1450. Ash plumes rose as high as 2 km above the crater and drifted NW. Ashfall occurred in the Central Valley and in the capital of San Jose (30 km WSW), and caused the closure of the Juan Santamaria International Airport, 48 km W, which reopened during the evening on 13 March. The local Tobias Bolanos airport (40 km WSW) closed intermittently. On 13 March two short explosions occurred at 1045 and 1100, and then a third occurred at 2100. According to the VAAC, ash plumes that day drifted 45 km NE at an altitude of 9.1 km (30,000) a.s.l. and drifted over 35 km W at an altitude of 6.1 km (20,000 ft) a.s.l.

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.

Sources: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA), Washington Volcanic Ash Advisory Center (VAAC), Comisión Nacional de Prevención de Riesgos y Atención de Emergencias (CNE)