“…Nonetheless, it is recognised that liquid-filled pores in rock matrix exhibit lower S-wave velocity than those without fluids 38,56 , while high-pressurized gas-saturated porous media could be associated with high S-wave velocity 42,57 . At Vulcano, the high anomalies are interpreted as: (1) cold, dry, and locally hardened intrusive magma bodies 34 ; or (2) high-pressurized hydrothermal fluids, mainly gas-saturated porous media 42 . On the other hand, the low anomalies are interpreted as: (1) variations in hydrothermal fluids, magmatic fluids and/or partial melts content 36,38,58,59 ; or (2) unconsolidated volcanoclastic materials emplaced during the successive caldera collapses 36,42,59 .…”