Surprising as only Mount Etna can be … it gives, on the eve of the August 15th Midsummer Festival, an eruption that almost no one expected. The last paroxysmal event had occurred in May 2023, and since then the volcano had remained in apparent calm. The tremor vacillated continuously, but the gases did not find the right power to bring the magma to the surface, so everything proceeded calmly. Not even the many tourists who flock to Sicily these days expected this … gift.
A surprise eruption
Until the morning of August 13th, 2023, the high-altitude excursions and guided tours to the summit craters continued as usual, according to the usual rhythms dictated by Etna’s mass tourism days. Even in the afternoon, despite the cloud cover caused by the high humidity, the volcano was crowded. The tremor graph showed some rising lines, but not enough to suggest an imminent event.
Everything changed within an hour or so.
A sudden surge in the signal, an increase in the rumbles at the summit … around 7 pm (luckily two hours after the closure of the climbing facilities to the craters!), here are the first fountains of lava from the South East Crater (SEC). The eruption started almost in secret, behind the dense blanket of clouds that covered Etna until 9:30 pm. Many therefore saw the beginning only thanks to the thermal cameras placed at high altitude.
Etna, night of fire
The SEC, the undisputed protagonist of the volcano’s last 50 years of life, began to emit Strombolian explosions at a rapid pace. Throughout the evening it provided an exceptional “tourist” show. Things then changed, overnight.
The lava fountains turned into one bright, very loud, giant fountain! The partial cover due to the strong emission of ash clouds almost hid its beauty for several hours, but the powerful roars that echoed all over the coast – and the red glow at the top – made it clear what was happening at the top.
At about 4 in the morning it all ended as suddenly as it had begun. Only the ash emission remained which hit the south-west belt of Etna, falling on Catania, Bronte and Paternò. In the morning, the technical report from the experts of the INGV of Catania arrived, which we report below.
Eruption August 13, report by volcanologists
“The National Institute of Geophysics and Volcanology, Etna Observatory, communicates. From the analysis of the surveillance cameras of the INGV-OE it has been observed that the lava fountain activity of the SE Crater, reported in the previous press release, during the night produced a volcanic cloud which dispersed in a SOUTH direction, producing a fallout of ash in the southern sector of the volcano and beyond.
The lava fountain activity ceased starting around 03:20 GMT, and subsequently the SE Crater was affected by a weak ash emission which, starting around 05:50 GMT, became discontinuous and confined to the summit area of the volcano. Finally, the lava overflow involving the south-western flank of the SE Crater is cooling as it is no longer fed.
During the night the seismic and infrasonic activity further intensified and after reaching the maximum values around 01:20 UTC, starting from 02:50 they showed a rapidly decreasing trend. From 03:20 UTC the average amplitude of the volcanic tremor settled in the medium level (where it still remains) and reached values comparable to the pre-eruptive ones around 03:30 UTC. The centroid of the volcanic tremor sources is located at the South-East Crater, at an altitude of about 2700m above sea level.
The infrasonic activity, which during the night followed the same temporal trend as the volcanic tremor, is currently quite modest; the recorded infrasonic transients, all of low energy, are now located at the Bocca Nuova crater.” (photos by Grazia Musumeci—13/08/2023)