OVSICORI-UNA reported that daily events at Turrialba during 27 September-1 October and on 3 October generated plumes that rose as high as 1 km above the crater rim and drifted NW, W, SW, and S. On 30 September explosions ejected hot material out of West Crater and minor ashfall was reported in Coronado (San José). Ash fell in Santa Cruz (7 km SE), Las Verbenas, Santa Teresita, Calle Vargas, Guayabito, and La Isabel on 3 October.

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)