How does Etna produce its fiery mix of magmas? One possibility is that the two magmas form at different locations and mix somewhere within Etna’s plumbing system. This hypothesis would imply that the magma below the Aeolian Islands travels more than 100 kilometers along a tectonic fault to Etna. It is considered highly unlikely, though, that such an underground magma passage exists. Researchers think it is more probable that the two magma sources are mixing.