On 1 November OVSICORI-UNA reported that since 24 October emissions at Turrialba were continuous with plumes rising 500 m above the crater rim. In addition, seismicity was characterized by banded volcanic tremor, long-period earthquakes, and low-amplitude volcano-tectonic earthquakes. Passive ash emissions were visible during 1-6 November. A 70-minute-long event began at 0530 and generated plumes that rose 500 m and drifted SW. Several short-duration (2-3 minutes) events were recorded at 1523 and 1703 on 2 November and at 0109 on 3 November; they generated ash plumes that rose 500 m. Ashfall was reported in Coronado. Seismic activity remained high, with moderate-to-high amplitude banded tremor. At 0620 on 5 November a plume rose 600 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)