In JGR Solid Earth, Sébastien Pilet's team said Sicily's 3,403-metre volcano formed from magma leaking from a mantle low-velocity zone through deformed tectonic plates.
Their geochemical analysis suggests Etna first produced silica-rich lava after crustal interaction, then later erupted smaller volumes of alkali-rich magma through a more direct conduit.
The study says Etna fits none of the three standard volcano classes and may reveal a wider role for the lithosphere in driving volcanic activity beyond Sicily.
Earth's Etna and Mars share deep mantle melt zones. Could this discovery unlock the secrets of volcanism on other planets?
Etna's magma is squeezed out like a sponge. Does this make Europe's most active volcano more predictable or more dangerous?
Etna reveals a new volcanic category. How many other 'unique' volcanoes worldwide have we been misclassifying for years?