On 17 July, the latest in a series of violent eruptions from the south-east crater of Mount Etna (3315 m) led to a very spectacular eruption.
17 February 2021
23 July 2001
This was the first since a large similar event in 1991–1993.
In the following days, ash frequently rained down on Catania, forcing repeated closures of the international airport. On 22 and 23 July, this flank eruption continued with great force, with a towering ash column rising from the explosive vent at about 2600 m elevation. The ash cloud drifted south-eastward, directly over Catania, dropping fine dark grey ash onto everything.
In the Meteosat-7 visible image (Figure 1) the ash plume is clearly visible as a bright band caused by the high reflectivity of ash particles when compared with the dark water surface.
While the wind direction was generally from the north-west (typical for the time of year), it varied in direction slightly during the day leading to an undulating structure of the plume.
Furthermore, during the afternoon, the plume broadened slightly in the horizontal due to the onset of convection, which is also visible from the development of small cumulus clouds over Mount Etna. The ash cloud, which totally obscured the sun over Catania, remained compact over a long distance until it dissipated and became invisible over the island of Crete (about 800 km distance to the south-east).
The eruption of the Etna volcano and related atmospheric pollution was also closely monitored using data from the GOME (Global Ozone Monitoring Experiment) instrument on the ERS-2 platform. GOME is a nadir-viewing across-track scanning spectrometer that measures radiance back-scattered from the atmosphere and the surface of the earth in the ultraviolet and visible range allowing the retrieval of concentration of trace gases such as ozone (O3), sulphur dioxide (SO2) etc.
Figure 3 shows a three-day composite of the SO2 concentration derived from GOME data. The satellite data shows a region south-east of Sicily where the atmosphere is polluted with a concentration of SO2 up to ten times higher than normal.
The retrieval method for trace gases from GOME-2 data is currently being developed at DLR in the framework of the EUMETSAT Satellite Application Facility (SAF) on Ozone Monitoring.
ATSR on ERS-2 (infrared and 11 micron channel) , 24 July 09:52 GMT (Credit: European Space Agency)
AVHRR on NOAA-15 (infrared) , 23 July 04:24 UTC (Credit: NOAA )
Mount Etna and ash plume as seen from MODIS instrument on Terra platform, date unknown (Credit: DLR)
Digital image of Mount Etna from ISS , taken by one of the Expedition Two crew members, 22 July. Download full resolution image.
SEAWIFS on SeaStar spacecraft, 24 July afternoon (Credit: NASA Goddard Space Flight Center)
MISR on Terra platform (stereo anaglyph created from instrument's 46° & 70° forward views), 25 July, (Credit: Jet Propulsion Laboratory, MISR Team)
Other Mount Etna cases
Mount Etna erupts on Christmas Eve
On Christmas Eve 2018 Mount Etna, Europe's highest and most active volcano, started erupting.
Etna volcanic eruption
Etna woke up again in the evening of 15 March 2017, spewing ash and SO2, and forming a nice looking plume.
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