Seismic radial anisotropy beneath Mount Etna (Sicily, Italy) generated by deep mantle upwelling

The central Mediterranean provides a key setting to investigate links between mantle upwelling, subduction, and arc volcanism. In southern Italy, rapid slab retreat and segmentation of the Calabrian subduction zone favor mantle flow, yet direct seismic evidence for mantle upwelling remains scarce. Here we present 3-D radial anisotropic tomography of the Calabrian subduction zone, derived from joint inversion of local and teleseismic traveltime data. Our results show a pronounced low-velocity (low-V) anomaly beneath Mount Etna (Sicily, Italy), located at the Ionian slab edge and connected to a broader low-V zone beneath the northeastern African margin. The anomaly exhibits negative radial anisotropy, consistent with vertical mantle flow, but its relatively weak magnitude suggests a waning upwelling flux. This feature extends at least below the mantle transition zone, favoring a contribution from the lower mantle. Our findings provide new seismic constraints on the mantle source of Etna and its geodynamic links to subduction processes.