Subcircular conduits and dikes offshore the Somma-Vesuvius volcano revealed by magnetic and seismic data

We analyzed new magnetic, bathymetric, and seismic data acquired in the offshore sector of
Somma-Vesuvius volcano (Italy). We detected a group of high-intensity, short wavelength magnetic
anomalies corresponding to partly buried volcanic dome-like structures located by seismic data. The
magnetic anomalies are aligned along a NW-SE strike that is the preferential orientation of an eruptive
fracture of the pre-19 ka activity of Vesuvius. Four cones emplaced after the Last Glacial Maximum (19 ka),
whereas a fifth one emplaced more recently suggesting a rejuvenation of the eruptive system offshore the
volcano in historical times. We also identified a NE-SW elongated magnetic anomaly consistent with a
dike-like body associated to an on-land tectonic structure that was active in recent times at Vesuvius. A
delta-like area with diffuse low-intensity magnetic anomalies reflects the seaward fronts of lava flows that
entered the sea mainly during the Middle Ages.