News Excerpt: 

Mount Etna, the largest volcano in Europe, and among the world’s most active and iconic volcanoes, has been sending up almost perfect rings of smoke into the air. The rings are a rare phenomenon that scientists refer to as volcanic vortex rings.

What and where is Mount Etna?

• Mount Etna, referred to as Etna, is an active volcano on the east coast of Sicily. 
• The largest island in the Mediterranean Sea, lying just off the toe of the Italian “boot”. 
• Etna’s peak is the highest in Italy south of the Alps, and It is Europe’s largest and one of the most active volcanoes.
• Etna’s summit has five craters, which are responsible for most of the volcano’s eruptions. 
• There are also “flank” eruptions that occur out of 300-odd vents of varying sizes along the slopes of the mountain.
• Etna is highly active, with at least 60 flank eruptions and numerous summit eruptions since 1600. 
• Recent summit eruptions occurred in 2006, 2007-08, twice in 2012, 2018, and 2021. 
• Flank eruptions happened in 2001, 2002-03, 2004-05, and 2008-09.

• Etna has been a World Heritage Site since 2013.
• According to UNESCO, the volcano’s eruptive history can be traced back 500,000 years. 
• At least 2,700 years of this activity has been documented.

What are volcanic vortex rings?

• Vortex rings are generated when gas, predominantly water vapor, is released rapidly through a vent in the Etna’s crater of a volcano.
• If the vent is nearly perfectly circular, the vortex rings formed will be circular in shape.
• The phenomenon of volcanic vortex rings was first observed and documented at Mount Etna and Mount Vesuvius in Italy in 1724, with an engraved plate depicting it from 1755.
• In more recent times, volcanic vortex rings have been observed at various volcanoes, including Redoubt (Alaska), Tungurahua (Ecuador), Pacaya (Guatemala), Eyjafjallajökull and Hekla (Iceland), Stromboli (Italy), Aso and Sakurajima (Japan), Yasur (Vanuatu), Whakaari (New Zealand), and Momotombo (Nicaragua).
• According to volcanologists, volcanic vortex ring formation is similar to how dolphins blow bubble rings. 
• The process involves compressing the gas (water vapor) then pushing it out through a circular aperture, creating a high-pressure zone that forms the vortex ring shape.
• The size of these vortex rings can range from a few meters to several tens of meters in diameter, and they can persist for several seconds before dissipating.
• The occurrence of volcanic vortex rings is relatively rare, as it requires specific conditions within the volcanic crater, such as the presence of a circular vent and the appropriate gas pressure and composition.
• The study of volcanic vortex rings has gained momentum in recent years, with researchers investigating their dynamics, formation mechanisms, and potential implications for understanding volcanic processes and monitoring volcanic activity.

Is Etna well known for this phenomenon?

• According to volcanologists, Etna is known for producing "dozens of gas rings every day," 
• According to volcanologists, no volcano on Earth produces as many vapor rings as Etna," indicating that Etna is particularly prolific in producing these rings.
• Last year "The rings“were produced by the explosion of gas bubbles within a narrow conduit, which shoots the gas at high speed toward the surface. 
• Attrition along the conduit walls slows the movement of the gas jet, relative to the center of the conduit”.
• According to volcanologists, while volcanic vortex rings are "not as rare as is often said,"Etna is "a particularly prolific producer of such rings."