On the 22nd April Calbuco volcano, Chile, erupted for the first time since 1972, with very little warning. Plumes of volcanic ash reached heights of 16 km on the 22nd and up to 17 km in a second, longer duration eruption that began in the early hours of 23rd April. A third eruption occurred on the 30th April with a ash heavy plume that reached heights of 5 km and lahars on the slopes of Calbuco. Large volumes of SO2 were released during the first days of the eruption
Sentinel-1 interferogram showing subsidence at Calbuco during eruptions on the 22-23rd April 2015. Each full colour cycle represents ~2.8 cm of motion away from the satellite.
Several thousand people were evacuated from villages closest to Calbuco . Ash fell over an area extending from the west coast of Chile to the east coast of Argentina, and grounded air traffic in Chile, Uruguay and Argentina.
There appears to have been only a very brief period of precursory activity before the 22nd April eruption. No deformation was measured in Sentinel interferograms from the month before the eruption up until the 21st April. The first co-eruptive interferograms (14th – 26th April) at Calbuco show subsidence on the western flank of the volcano of ~ 12cm. The topography of the volcano’s crater has also changed, possibly due to ice melt as well as the eruption.