OVSICORI-UNA reported that high-amplitude tremor at Turrialba began at 0145 on 16 June, accompanied by passive ash-and-gas emissions that rose 500 m above the crater. Tremor and emissions ceased at 0715. Emissions of ash and gas were again observed at 0805, for a brief 10-minute period, and at 1557. A vapor plume with minor amounts of ash was visible at 1700. On 19 June tremor began at 0410, along with passive ash-and-gas emissions that rose 500 m above the crater and drifted NW. Tremor significantly decreased at 0825. Tremor signals recorded at 1158 on 20 June indicated ash emissions; the wind direction was 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)