Near-perfect circles of gas emerged from Mount Etna in a rare display captured on camera on Saturday, 6 April. Volcanic vortex rings have blown into the sky from the largest active volcano in Europe since Wednesday. Scientists say Mount Etna sees the rare phenomenon, caused by a constant release of vapours and gases, more than any other volcano on Earth. The rings spewed out of a new crater that opened on Tuesday on Etna’s summit. There were no reports of disruptions at Catania airport.