The volcano has emitted hundreds, perhaps thousands, of the spectacular rings since then, added Mr Behncke, who can see the volcano from his house in Tremestieri Etneo, near Catania.
Locals have dubbed the volcano Lady of the Rings due to the circles of vapour it has been emitting.
“I thought I had hallucinations. I had never seen anything so spectacular and beautiful,” said Angela Intruglio, from Mascali, a town at the foot of Mount Etna that had to be rebuilt after it was destroyed completely in an eruption in 1928.
Experts say the unusual rings are harmless and aren’t necessarily a prelude to an imminent eruption.
“It’s only an open conduit, of a circular shape, through which the gas is shot in a pulsing way,” said Mr Behncke. “It’s really something extraordinary and completely innocuous.”
The previous time it happened at Mount Etna was last December, said Giuseppe Barbagallo, a guide at the South Etna Alpine Guides Group. Other major emissions of rings occurred in 2000 and 2023.
At 11,000 feet, Mount Etna is the tallest volcano in Europe. Eruptions have been ongoing for half a million years, according to Mr Behncke’s institute, but the volcano only acquired its characteristic conical shape in the last 100,000 years.
Magma climbs up Mount Etna through a central open conduit which constantly releases gas, meaning smoke is almost always emanating from its top.
The last major eruption was in May 2023, which forced airport authorities to halt all flights at the nearby airport of Catania, which is a popular tourist destination.
At the time, the eruption of lava from its southeast crater produced a cloud of black volcanic ash that fell on the city, causing disruption not only to air traffic but also vehicles on the ground.
The same happened because of the eruptions of 2001 and the following two years, when a layer of lapilli and ashes formed on streets and motorways endangering car circulation. The same applied when they fell on the airport runway.
The Institute also said that thin volcanic dust can irritate people’s eyes, skin and throats, while crops can suffer irreversible damage due to the ashes and lapilli transported by the wind, in case of eruptions.
Many major eruptions have occurred over the last 100 years. In 1971, several villages were threatened by lava flows, which destroyed some orchards and vineyards. Over the following decade, the volcano’s activity was almost continuous. In 1983, authorities set off dynamite in an attempt to divert lava flows, following an eruption which lasted four months.
