Etna is no stranger to surprising. But this time he did it in a completely new way: his voice reached all the way to space. For the first time, a group of Italian researchers has measured the disturbances caused by a volcanic eruption in the ionosphere, the layer of the atmosphere that extends from approximately 60 to over 1,000 kilometers above sea level.
The study, published in Earth and Space Science with the title “Ionospheric Disturbances During the 4 December 2015, Mt. Etna Eruption”, is signed by a team from the National Institute of Geophysics and Volcanology (INGV) together with the universities of Trento, Catania, Calabria and Sapienza of Rome, in collaboration with the Institute of Atmospheric Physics of Prague.
Scientists analyzed the eruption of December 4, 2015, when a spectacular lava fountain from the Voragine crater pushed a column of volcanic material up to 13 kilometers into the air. Since then, the network of over 200 GNSS satellite receivers distributed across Sicily and Southern Italy has recorded variations in total electron content (TEC), a parameter that indicates the density of electrons in the ionosphere.
The anomalies appeared 20–30 minutes after the start of the eruption, coinciding with the growth of the eruption column, and propagated for about 200 kilometers towards the southwest. “We have demonstrated that even a ‘local’ eruption leaves a trace in space,” explains Federico Ferrara (University of Trento – INGV Etneo Observatory). “Ionospheric observations can complement traditional monitoring, opening up new perspectives.”
The oscillations detected had periods of 15–25 minutes and amplitudes of approximately 0.6 TECU, values consistent with the so-called atmospheric gravity waves, generated by the rapid rise of the column of ash and gas. These waves, rising upwards, transfer energy to the outermost levels of the atmosphere, where they can be intercepted by satellites.
“Such rich data allowed us to recognize weak but significant oscillations,” underlines Michela Ravanelli of Sapienza University of Rome. “It is an important step towards the integration between volcanology and space sciences.”
For Alessandro Bonforte of INGV, the discovery shows how “the monitoring networks created to study the lithosphere can also be used to investigate upward disturbances, offering an integrated vision of the Planet, from underground to space”.
Forecasting and warning models
The result is not just a scientific curiosity. Understanding how an eruption affects the ionosphere could in fact improve prediction and warning models by integrating seismic and thermal data with satellite data. The researchers point out that ionospheric signals are not in themselves precursors of eruptions, but can “help reconstruct energy release processes and build more accurate eruption scenarios.”
The study is dedicated to the physicist Vincenzo Carbone of the University of Calabria, who recently passed away and was awarded the Lewis Fry Richardson Medal in 2025, recognition for his contribution to the physics of complex systems.
Etna, with its intense activity and dense network of sensors, confirms itself as an exceptional natural laboratory. A volcano that not only shakes the Earth, but – as this study demonstrates – also makes the atmosphere vibrate up into space, reminding us how deeply interconnected the processes that link our planet to the cosmos are.
