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What processes are responsible for Etna’s frequent eruptions?
24 April 2024
Dr Adam Cotterill took part in the project that aims to provide more insight into the processes that are responsible for Mt Etna’s frequent eruptions.
Image: Adam at Bocca Nuova Crater, our field site for the week.
I recently spent a week on Mt. Etna (Italy) Europe’s tallest and most active volcano as part of a collaborative project with Istituto Nazionale di Geofisica E Volcanologia (INGV) and Palermo, Cambridge, Manchester universities. The aim of this project was to collect samples from Etna’s persistent gas plume using drone mounted equipment to help reveal the processes responsible for Etna’s frequent eruptions.
Thumbs up if you just missed a perfect gas pulse while changing batteries!
A strong pulse of gas emanating from one of the vents within Bocca Nuova.
An example of Etna’s “smoke rings”
Piloting the sampling drone into the gas plume above Bocca Nuova. The near side of the Southeast Crater is on the right.
Combined INGV, Palermo, Cambridge and UCL field team en route to Mt Etna’s summit (3300 m) mostly by 4x4. Image Courtesy of Marie Edmonds.
My role was to operate the ultraviolet and infrared cameras that would collect the SO2 flux and plume temperatures as the samples were collected. Once these instruments were set up we waited for the wind to reduce so we could fly the drone during which Etna treated us to a display of its famous “smoke rings” caused when conditions are just right that the gas plume forms a vortex just like Gandalf and Bilbo in The Lord of the Rings but on a far grander scale!
Once the wind died down I was asked whether I wanted to pilot the drone for the first sampling flight which was really exciting but very nerve-racking having the fate of the entire campaign suddenly thrust into my hands! However with the aid of Dr Emma Nicholson, my supervisor, drone pilot instructor and now co-pilot nothing went awry. Due to the high winds we had to take off in between gusts and hover within the plume while we waited for high enough CO2 concentrations to be measured and then trigger the sampling system. This wait quickly drained the drone’s batteries and we often missed the larger gas pulses with the necessary CO2 concentrations while changing batteries.
The next day the winds were much calmer which allowed us to try a new technique of waiting for the audible thud of the next gas pulse arriving and launching the drone to intercept the pulse within a matter of seconds. The time between pulses was anywhere between 10-20 minutes which led to tense waits. After a few mistimed take-offs, I finally managed to intercept a pulse and was quickly rewarded with the shout “1000 ppm! Starting sampling!” from team leader Dr Joao Lages (Palermo/UCL). Following this successful run we spent the next days perfecting this method and filling all our sample bags.
This left one last challenge set by Prof. Sandro Aiuppa (Palermo), who was curious as to the current gas composition of the Southeast Crater - Etna’s current eruptive centre. So on the last day, with our last set of batteries I flew our drone from Bocca Nuova to the Southeast crater, over a kilometre away and out of line of sight. With limited view from the drone’s camera and the live feed from the gas sensor onboard we managed to fly into the plume and measure the composition. The was the first time an instrumented drone had been flown into this crater.
This field work represented the highlight of my PhD, the fieldwork component of which was scuppered by Covid. So I am thankful for the opportunities to join field work on multiple projects in Italy and Iceland provided by Emma Nicholson and our collaborators.