Mount Etna is a volcano in constant transformation. It has changed its face dozens of times over the millennia and still does. Volcanologists have identified a constant mutation in the “behaviour” of the mountain, which once every 10 or 15 years or so erupts in a different way. In fact, it alternates periods of calm and effusive eruptions with periods of violent paroxysms. The eruption of Christmas 2018 falls into the latter range of events, which kicked off the second “decade of paroxysms” of the new millennium.
Before the eruption: the restless year 2018
Etna came from a relatively “calm” period, after the ferocious paroxysms of the years 2000-2003. The volcano continued its lively activity, but with a certain balance acquired over the previous decade. Since the end of 2017, however, something was changing. Earthquake shocks, explosions at the top had heralded a state of unrest that would intensify during 2018. The population, though, barely noticed the change, because there had been few “visible” episodes that year. But internally the magma filled the ducts and Etna swelled in a worrying way. In the autumn of 2018, volcanologists were already studying evacuation plans for a possible lateral eruption, given the increase in pressure especially along the lower flanks.
The Christmas Eruption
An important seismic swarm began to affect the south-eastern belt of Etna between 23 and 24 December 2018. And at 9:30 in the morning on Christmas Eve the famous lateral eruption finally started. Fortunately for the inhabitants, it developed much higher than expected. In fact, the fracture opened just below the summit craters, still on the side of the main ducts, but very far from inhabited centres.
The lava flow that came out, however, turned out to be very little nourished and during the following three days it stopped completely, covering a few kilometres. The volcano remained full of magma and still under pressure. A pressure that was partially vented on the night of 26 December, with a 4.8 Richter earthquake that caused collapses and damage in a large part of the local municipalities (Viagrande, Aci Bonaccorsi, Aci Sant’Antonio, Acireale, Zafferana and Milo).
Such a short eruption and such a strong earthquake were not a sign of balance, which is why the experts continued to be on the alert. The unpredictable could still happen, and anywhere on the body of the volcano. But Mount Etna was going to surprise everybody, once again.
The Etna show
All the retained energy and all the accumulated magma were never expelled in a large, catastrophic lateral eruption, as everyone feared. Mount Etna managed to “pay in installments” of its power, starting a show that would last three years. From 2019 to 2021, in fact, an incredible series of spectacular paroxysms would have allowed the volcano to empty itself. The magma was released through lava fountains and ash columns immortalized in dozens of photos and videos.
The Christmas 2018 eruption, therefore, was the starting spark for a new period (decade?) of particular eruptive events, which we are still experiencing today. The “Etna show” is still going on, and today it alternates moments of violent explosions with sudden mini eruptions at the summit. Since June 2022, some fractures that have opened in the lower part of Valle del Bove have occasionally released small quantities of lava. However, it is a sign that the volcano still has “a lot” to give. And one always hopes it doesn’t give it devastatingly, all at once.
After the eruption…
After the Christmas 2018 eruption, the damage count remained in the earthquake-stricken towns. A less dramatic count than expected, with only a few injured people and no dead. Even the collapses were less than expected, a sign that those populations – already affected by the 1984 earthquake – had worked well together with expert geologists to rebuild according to safety criteria. The Christmas 2018 eruption also launched the important “fault mapping” project, which will allow building in an increasingly correct and safe way in the future. (all photos by Grazia Musumeci)