The holocene marine record of unrest, volcanism, and hydrothermal activity of campi flegrei and somma-vesuvius

This chapter illustrates the marine record of a spectrum of volcanic, hydrothermal, and sedimentary features that characterize the Latest Pleistocene-Holocene evolution of the Naples Bay offshore Campi Flegrei and Somma-Vesuvius. The work is based on review of previous literature integrated with interpretation of new high-resolution marine Digital Terrain Models (DTMs) derived from swath bathymetry surveys and high-resolution reflection seismic profiles calibrated with marine gravity core data. Seismic profiles from Pozzuoli Bay provide detailed images of the ring fault system and resurgent dome associated with the evolution of the Neapolitan Yellow Tuff (NYT) collapse caldera and document a series of uplift episodes associated with volcanic unrest as documented on land throughout the Holocene, with a notable subsidence phase occurring between ~ 2.5 ka BP and 1538 CE (Monte Nuovo eruption). Offshore seismic images also revealed the occurrence of ascending hydrothermal fluids and volcanic/subvolcanic intrusions along the ring fault zone of the NYT caldera. Seismic data acquired along the SW submerged slope of Somma-Vesuvius display evidence of gravitational instability, associated with slump folding and faulting, of sand waves originated by pyroclastic flows that entered the seawater after destroying the Roman city of Herculaneum during the 79 CE eruption of Vesuvius. Between the Somma-Vesuvius and Pozzuoli Bay, seismic profiles calibrated with gravity core data revealed the occurrence of a hummocky seafloor region, known as Banco della Montagna (i.e., the Montagna bank). This volcanic bank was shaped by the dragging and rising up of volcaniclastic diapirs (mostly unconsolidated pumice) because of pore fluid overpressure at depth and associated active fluid venting at the seafloor.