Mount Etna was a volcano in Italy. It is located on an island near Italy and has been erupted many times throughout the 2000s to the 2010s.
During the 2012 apocalypse, Mount Etna presumably erupted which destroyed major cities living on the island and its pyroclastic flows rendered it uninhabitable. Mount Etna and the rest of the island were swept by a megatsunami during the Worldwide Flooding.
When the apocalypse ended, Mount Etna became dormant and was submerged underwater, rendering it uninhabitable.