Mount Etna Puffs ‘Smoke Rings’ Into the Sky

Sicily’s Mount Etna, the tallest active volcano in Europe, drew attention last week, but not because of a volcanic eruption—it’s blowing circular rings of vapor from its top.

These “smoke rings," which are called volcanic vortex rings by scientists, are made up of gas and water vapor shot from a newly formed crater, writes the Washington Post’s Leo Sands.

Researchers have previously observed volcanic vortex rings at a number of different volcanoes, according to a 2023 study on the rings’ dynamics in the journal Scientific Reports. Etna’s new rings were first spotted last Wednesday.

The cold atmosphere above the hot volcano causes the water vapor to condense, making the rings visible, per the study.

“On its own it is colorless, but once it reaches the condensation level then it becomes whitish—and that’s what we are seeing,” Ana Casas Ramos, a volcanologist at the Australian National University, tells the Australian Broadcasting Corporation (ABC). “The water vapor is coming out very hot and then once it reaches shallow levels, like atmospheric levels, it then encounters cold air and that’s when you get this condensation.”

“The rings look pretty much like the ‘smoke rings’ produced by an able smoker,” Boris Behncke, a volcanologist at the Italian National Institute of Geophysics and Volcanology’s Etna observatory, writes in an email to the Washington Post.

Mount Etna blows spectacular smoke rings into the sky

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Etna stretches around 10,900 feet high and covers an area of about 600 square miles. The volcano has been active for the past 2.6 million years. It has erupted dozens of times in recorded history, including a particularly intense 1669 eruption that spewed 990 million cubic yards of lava and destroyed a dozen villages, per the Encyclopedia Britannica.

The volcano has had recurring periods of activity throughout the 20th and 21st centuries, including last November.

Observations of rings above Etna, as well as Italy’s Mount Vesuvius, destroyer of Pompeii, date back to 1724, according to the 2023 study. More recently, vortex rings have also been spotted at volcanoes in Alaska, Ecuador, Guatemala, Japan, Vanuatu, New Zealand and Nicaragua.

Scientists previously weren’t always sure how these rings were being made, and the 2023 study dove into the mechanism using computer simulations, according to National Geographic’s Robin George Andrews.

Their results showed that in order for the rings to take shape, gas bubbles need to be released from the top of a channel carrying magma to the surface. “Imagine a very narrow, cylindrical conduit, within which, at a certain depth, there is magma,” Behncke writes via email to the Washington Post. “Every so often, a bubble forms at the surface of the magma, bursts, and sends a slug of gas at high speed through that conduit.”

The gas rolls up the sides of the vent, forming the ring shape that becomes visible via condensation, per the 2023 study. The vent has to have a roughly circular shape with sides of the same height in order for the ring shapes to form, according to National Geographic.

The rings’ white color indicates that they’re mostly water vapor, per the study. Behncke tells the Washington Post that the rings are about 80 percent water vapor, and the rest is mostly sulfur dioxide and carbon dioxide.

Casas Ramos tells the ABC that the degassing lowered the probability of explosive eruptions. “If it does culminate in an eruption, let’s say in the coming months or weeks, it’ll be just a couple of puffs, a bit of ash, maybe a bit of magma but nothing violent,” she says to the publication.

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Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.