Ebmeier, González, Bagnardi, Carboni, Hayer, Pyle & Mather
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. Over about 7.5 hours Calbuco is thought to have erupted around 0.2 km3 of ash.
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. The area worst affected by ash fall extends north and east from Calbuco, where ash thicknesses were around 50 cm, towards Bariloche, where about 1 mm of ash has been reported. Intermittent, low-level ash plumes continue to rise from the vent, and there is a continuing hazard associated with secondary lahars around the volcano.
There appears to have been only a very brief period of precursory activity before the eruption. A swarm of volcanic tremor earthquakes began at 15.11 and continued until the start of the eruption at 18.05 local time (SERNAGEOMIN). No deformation was measured in Sentinel interferograms from the month before the eruption up until the 21st April.
The difference in backscatter of Sentinel images acquired on the 14th and 26th April show that the topography of Calbuco’s crater changed during the eruption (Figure 2). In particular, some material seems to have been removed from the summit, potentially part of the ice cap, leaving a much deeper crater than was there previously.
All Sentinel-1 results are Derived Works of Copernicus data (2015), subject to the following use conditions: “TERMS AND CONDITIONS FOR THE USE AND DISTRIBUTION OF SENTINEL DATA“.

![Figure 4. Data, spherical source elastic half space model and residuals for recent deformation at Calbuco [Bagnardi].](http://tempcomet.leeds.ac.uk/wp-content/uploads/2015/04/Figure-4.-Spherical-source-Calbuco-300x137.png)