Seismic stratigraphic analysis of a submarine volcanic field allows the recognition of complex stratal architecture due to the interplay between the syneruptive and intereruptive stratigraphic units. This approach was applied to the offshore Campi Flegrei, eastern Tyrrhenian Sea margin. The area features Late Quaternary volcanism, shallow magmatic intrusions, and thick intereruptive volcaniclastic wedges. Seismic stratigraphic analysis is constrained by marker seismic reflectors defining volcanic boundaries and tied to wells drilled in Naples city, cropping out volcanic units, and a chronostratigraphic framework recognized within the Bay of Naples succession. On the basis of seismic configuration, it was possible: (1) to detect various typologies of magmatic features, such as scoria cones, tuff cones, domes, dikes, and pyroclastic flows; (2) to recognize three types of unconformities; and (3) to reconstruct the relation between monogenetic volcanoes and intereruptive sedimentary units. The eruptions of monogenetic volcanoes deeply modified the paleogeography of the Bay of Naples, transforming an intraslope basin into smaller basins separated by volcanic ridges. The former were successively filled during the intereruptive periods. The sediments eroded in the shoreface and subaerial environment were deposited along the volcano margins. Prograding wedges were deposited during the fall of sea level and filled the seaways between volcanoes, whereas during the rising of the sea level, deposition migrated toward the volcano crater until the latter were drowned below sea level. This paper defines the stratigraphic evolution of the south margin of the Campi Flegrei volcanic field and provides both an example of seismostratigraphic analysis in a complex volcanic area and additional data for the volcanologic interpretation of the Campi Flegrei.

Campi Flegrei is a densely populated active volcanic field. Two major explosive volcanic events have led to the formation of nested calderas. Detailed stratigraphy of the volcanic rocks outcropping in part of this area contributes toward a better understanding and definition of the volcanic hazard. Our research activity focuses on the southwestern sector of Campi Flegrei including Procida Island. This area is particularly suitable for stratigraphic reconstruction due to the thick pyroclastic sequences exposed on the coastal cliffs. These sequences include several paleosol horizons and substantially represent the products of all the volcanic activity of Campi Flegrei. The onset of volcanic activity in this area is represented by products related to the activity of scattered vents of unconstrained age. From 74 to 55 ka, they were mantled by products erupted in the nearby island of Ischia. Circa 39 ka, the Campanian Ignim-brite eruption occurred in the Campi Flegrei area, producing a large caldera. A thick succession of welded pyroclasts, lithic breccias, and associated ash- and pumice-flow deposits was emplaced in the proximal area. The local activity resumed at 19–17 ka with the formation of monogenetic volcanoes. A phreatoplinian eruption (Neapolitan Yellow Tuff) occurred at 15 ka, which produced a second, nested caldera. Stratified yellow tuff volcanoes, ranging in age between 9 and 5 ka, developed along the Neapolitan Yellow Tuff caldera boundary. Minor tephra layers testify to the final explosive activity vented in this area.