Etna, the most active volcano in Europe, attracts the attention of scientists and tourists with its mesmerizing spectacle of strange “vortex rings”. These mysterious rings, made up of a mixture of smoke, steam and gases, erupt from a single vent located in the crater of Bocca Nuova. According to Boris Behnke, a volcanologist at Italy’s National Institute of Geophysics and Volcanology, the phenomenon has been observed for about a week and shows no signs of stopping.
Vortex rings form when gas bubbles explode in a narrow channel above a magma chamber. The force causes the gas to move toward the surface at high velocity. As the gas moves along the walls of the conduit, depletion slows its movement relative to the center, resulting in a ring shape. At Etna, a volcano known for its unique volcanic activity, more vortex rings form than at any other volcano in the world.
The secret to Etna’s vortex rings lies in the shape of the conduit below the vent in the crater of Bocca Nuova. A recent study published in the journal Scientific Reports showed that the combination of rapid gas release from gas bubbles and the correct shape of the ejection vent is required to form perfect rings. This unique combination is what accounts for the eerie perfection of Etna’s vortex rings.
Although vortex rings have been observed at other volcanoes, such as Stromboli volcano, they are rare elsewhere. Etna volcano’s propensity to form such rings has fascinated scientists for many years. In 2000, the volcano produced a record 5,000 vortex rings. The current figure is similar to that period, indicating a possible increase in volcanic activity.
According to Behnke, Etna’s recent activity, including the opening of a new vent in the Bocca Nuova crater and small eruptions in the Southeast Crater, does not mean a major eruption is imminent. However, these events are indicative of the dynamic nature of the volcano and its ongoing activity.
“Such gas rings are formed by the explosion of gas bubbles in a narrow channel [above the magma chamber] that ejects gas at high velocity toward the surface,” says Boris Behnke. “Depletion along the walls of the conduit slows down the motion of the gas jet relative to the center of the conduit,” he adds.
The mysterious swirling rings of Etna volcano continue to mesmerize scientists and tourists alike. The unique combination of the rapid release of gas and the regularity of the shape of the ejected vent creates these mesmerizing phenomena. Although further research is needed to fully understand the implications of the vortex rings, they serve as a reminder of the dynamic nature of one of Europe’s most active volcanoes.
