Mount Etna puffs smoke rings into Sicilian sky | Video

CATANIA, Italy -- Smoke rings were observed coming out of Sicily's Mount Etna on Sunday, after a vent opened on the southeastern crater last week.

Footage by Rosario Catania shows Europe's largest active volcano in action, with Catania telling Storyful that the rings are formed by "explosions of gas bubbles inside a narrow conduit above a magma chamber."

"As they escape from the mouth they have a rotating motion," he said.

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Boris Behncke, a local volcanologist from the National Institute of Geophysics and Volcanology in Catania, Italy, told local media that Etna produces more of these smoke rings than any other volcano on the planet.

There was no danger to humans or structures from this latest volcanic activity, Behncke said.