Mount Etna has long puzzled geologists because it doesn’t fit any of the three classic ways volcanoes are thought to form. A new study suggests it may instead be fueled by ancient pockets of magma that are pushed upward through cracks created by shifting tectonic plates. If confirmed, Etna could belong to a rare fourth category of volcano, revealing that much larger volcanoes can form through processes previously associated only with small submarine eruptions.
