Investigating the seismic structure of shallow magmatic conduits: Insights from the Salina Island (southern Italy)

Abstract

The plumbing systems of closely spaced individual volcanoes and volcanic fields may be very complex due to the interaction (or not) of different magma storage zones and magma pathways at variable depths. Ambient noise tomography unveils the shallow seismic structure of Salina Island (Southern Italy), which is characterized by 6 proximal and partly overlapping volcanoes developed between 244 and 15.6 ka. We use two months of continuous data from 40 nodal stations deployed in 2023 at uneven interstation distances. This seismic array yields tomographic maps down to 1.5 km depth in which the geometry of the volcano flank collapses and shallower plumbing systems of eruptive fissures are clearly imaged. Shear wave velocity maps reveal the main structures and deposits of the ‘twin’ stratovolcanoes of Monte dei Porri, to the west, and Monte Fossa delle Felci, to the east. High velocity anomalies beneath these volcanoes become less pronounced at ∼200 m b.s.l. revealing the transition from submarine to subaerial lava flows. 3D images of the eastward dipping subcircular conduits below the main volcanoes suggest that the deep feeding system is located offshore to the east.