Terra MODIS True Color RGB, 28 Feb 2021

Mount Etna very active in February & March 2021

16-28 February and 2-11 March 2021

Terra MODIS True Color RGB, 28 Feb 2021
Terra MODIS True Color RGB, 28 Feb 2021

In February and March 2021, regular Etna eruptions were observed from space.

Last Updated

10 June 2022

Published on

03 March 2021

By Jochen Kerkmann (EUMETSAT) and HansPeter Roesli (Switzerland)

On 16 February 2021, Etna started a series of very spectacular lava-fountaining eruptive episodes, known as paroxysms. The short, but violent paroxysms, produced spectacular fireworks of lava fountains and blanketed part of Sicily with black ash.

In total, eight short paroxysms (with durations of around 2-3 hours) were observed by Meteosat-11 in the period 16-28 February (Figures 1, 2 and 3), under perfect viewing conditions, i.e. no clouds obscuring the scene.

Mosaic of Meteosat-11 Ash RGB images for all 8 paroxysms
Figure 1: Mosaic of Meteosat-11 Ash RGB images for all eight paroxysms. The images capture the volcanic plumes about 2 hours after the start of the eruption.
Mosaic of Meteosat-11 Aimass RGB images for all 8 paroxysms
Figure 2: Mosaic of Meteosat-11 Aimass RGB images for all eight paroxysms.
Figure 3: Fast movie of eight Etna paroxysms between 16 and 28 February (Meteosat-11 Ash RGB).  Each eruption is followed for 3-4 hours.

Each time the volcano sent lava hundreds of metres (or even more than 1000m) high in the sky creating beautiful sceneries (especially in the night), it also injected a fair amount of ash and sulphur dioxide (SO2) in the atmosphere.

In the Ash RGB (Figures 1 and 3) the ash and SO2 plumes are seen in red/green shades, respectively. In the Airmass RGB (Figure 2), SO2 clouds appear with red hues — ash is not different from water cloud in the Airmass RGB.

Note that, due to hot lava flowing down the mountain, Mount Etna is clearly visible as hot spot in all eight cases (dark magenta pixels in the Ash RGB, black spots in the Airmass RGB).

The first of eight eruptions occurred on 16 February at around 16:00 UTC (17:00 local time), producing a tall ash plume that rose to up to approximately 10km elevation (30,000ft) above sea level, according to Volcano Discovery reports. The plume quickly moved southward driven by very strong upper-level northerly winds (Figure 4).

Me-11 24hr Microphysics 16 Feb
Figure 4: Meteosat-11 24h Microphysics RGB with geopotential 300hPa overlaid, 16 Feb 18:00 UTC. Credit: EUMeTrain

Only 32 hours later, Etna produced another impressive eurption (see 17 Feb image in Figures 1 and 2). The volcanic plume rose again to about 10km height. This time strong winds carried the SO2 plume in a south-easterly direction towards Libya.

While creating the animation of the 2nd paroxysm, we observed, in real-time, the 3rd paroxysm, which started on 19 February at 08:30 UTC (day-time eruption), exactly 33 hours after the 2nd eruption. The impressive eruption column, with circular umbrella cloud, could be observed from many places in Sicily. The high-level SO2/ice plume travelled eastward towards Crete, where it arrived in the morning hours of 20 February. Sentinel-3A OLCI captured Etna at 09:12 UTC on 19 February, around 40 minutes into the eruption (Figure 5).

Sentinel-3B OLCI True Colour 19 Feb 2021
Figure 5: Sentinel-3A OLCI True Colour, 19 February 09:12 UTC.

 

In the following days, Etna continued its regular activity, with a new paroxysm every 36-48 hours. Inhabitants of Sicily and experts around the world started to focus on the volcano and  predictions started to be made about when would be the next eruption.

Eruptions four, five, six and seven were again spectacular night-time events, very similar to the previous paroxysms. Only paroxysm number six (image from 23 Feb, Figures 1 and 2) was a bit different: it occurred only five hours after paroxysm number five, and it released a pure ash plume. As the high-level winds had changed to easterly directions, all the plumes from these eruptions headed towards western Sicily and the Tyrrhenian Sea.

Figure 6 shows two instances of the volcano plume at 00:33 UTC and 01:25 UTC on 23 February, captured by the Day-Night-Band (DNB) of VIIRS on NOAA-20 and Suomi NPP, respectively.

VIIRS and Day-night Band 23 Feb 2021
Figure 6: Day-Night-Band (DNB) of VIIRS at 00:33 UTC (left) and at 01:25 UTC (right) on 23 February, captured by NOAA-20 and Suomi NPP.

The imagery is enhanced using Zinke’s method, which clearly highlights the Moon-lit plume (three-quarter waxing Moon). Note in particular the fine cellular structure of the plume at 01:25 UTC, a pattern found in Dust-Infused Baroclinic cyclone Storm (DIBS) clouds and a sign for interaction of the volcanic ash with water cloud.

The last lava fountain episode, or paroxysm, of February occurred in the morning of Sunday 28 February, after a longer interval than the previous seven. After roughly three and a half days, the awaited number eight episode of the series of paroxysms occurred Sunday morning around 9am local time.

Figures 7 and 8 show close-up views of the ash/SO2 plume two hours after the start of the eruption. They show a higher-level ice/SO2 cloud (white in the True Color RGB, green in the Ash RGB) and a lower-level ash plume (brown in the True Color RGB, red in the Ash RGB). While the ash plume disintegrated quickly within a few hours, the SO2 plume travelled a long distance across the Mediterranean Sea towards Crete and further to the Middle East.

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Met-11 RGB comparison

Airmass RGB compare1
compare2
 

Figure 7: Meteosat-11 Ash RGB (left) and Airmass RGB (right) on 28 February at 10:00 UTC.