OVSICORI-UNA reported that an event at Turrialba at 1700 on 5 May generated a weak ash plume that rose 500 m above the crater and drifted SW. Two short-amplitude events occurred at 1702 and 1820 though there was no confirmation if they had corresponded to eruptions. During 5-7 May volcano-tectonic and long-period earthquakes were detected, as well as variable-amplitude tremor. At 1250 on 6 May an event produced a plume that rose 300 m and drifted W. Between 1250 and 1730 a passive ash emission rose no higher than 1 km. Another passive ash emission rose about 500 m at 1000 on 7 May and drifted WNW. At 0902 on 9 May an event generated an ash plume that rose 500 m and drifted NW.

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)