Report on Turrialba (Costa Rica) — 12 October-18 October 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 October-18 October 2016
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2016. Report on Turrialba (Costa Rica). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 12 October-18 October 2016. Smithsonian Institution and US Geological Survey.
10.025°N, 83.767°W; summit elev. 3340 m
All times are local (unless otherwise noted)
OVSICORI-UNA reported that tremor levels and ash emissions at Turrialba decreased around 1700 on 11 October. A small eruption occurred at 2132; ashfall was reported in Guadeloupe. Another event was recorded at 1620 on 12 October but weather conditions obscured views of any resulting emissions. On 13 October long-period earthquakes were associated with ash emissions that rose no higher than 500 m above the vent. Tremor amplitude increased around 1029 on 13 October and remained variably elevated at least through 15 October; emissions occurred at around 1029 and 2006 on 13 October, and almost continuously during 14-15 October, producing ash plumes that rose as high as 1 km. Ashfall and a sulfur odor was reported in areas downwind, near the volcano. On 16 October OVSICORI-UNA noted that the almost constant ash emission in the previous few days affected the operation and communication of various scientific instruments installed at the top of the volcano and surrounding areas; communication with two seismic stations located near the summit was lost. Webcams showed continuing ash emissions rising as high as 1 km during 16-18 October.
Geologic Background. 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.