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Detailed sedimentological analysis of Aptian/Albian shallow-water carbonate platform strata from Monte Faito, southern Italy, reveal composite sea-level change. The organization of the lithofacies and their related diagenetic overprint have allowed the identification of 50 elementary cycles. They often show exposure-related diagenetic features superimposed on subtidal deposits, suggesting drops of relative sea level. Elementary cycles are grouped into 16 bundles forming six superbundles. The hierarchical organization of the cycles are interpreted to be related to composite eustatic sea-level fluctuations driven by the Earth’s orbital perturbation in the Milankovitch frequency band. Moreover, the systematic variation of superbundle thickness and the general evolution of the lithofacies reflects variations of accommodation potential defining longer-term environmental changes. Different lithofacies forming elementary cycles are frequently separated by bedding planes that, when viewed in a sequence stratigraphic context, are interpreted as transgressive surfaces, maximum flooding surfaces or sequence boundaries. This allows the recognition of lowstand, transgressive and highstand deposits in the cyclic units. Considering both the bundle/superbundle ratio and the sequence stratigraphic interpretation of the superbundles, a chronostratigraphic diagram illustrating both gaps at bundle level and their expected location along the section was created. It establishes that the section developed over about 2.4 Ma.

The ad 79 Plinian eruption of Vesuvius that buried Pompeii and Herculaneum began with pumice falls deposited towards the SE of the volcano followed by pyroclastic currents directed towards the SW. These currents reached Herculaneum and rapidly entered the sea, forming a fan. The interpretation of seismic reflection profiles and gravity cores collected off Herculaneum documents a submarine fan-shaped pyroclastic body at 10–140 m water depth that we interpret as the submarine counterpart of the onshore pyroclastic current deposits. This fan, c . 0.3 km 3 in volume, displays a chaotic seismic facies that changes seaward to parallel reflectors and then to wavy reflectors. Gravity cores reveal a succession consisting of centimetre-thick sand- or silt-sized ash couplets followed by a graded gravelly sand-sized bed up to 180 cm thick, containing shell fragments and beach-derived pebbles, overlain by centimetre-thick graded and laminated sandy ash layers. The depositional textures and sedimentary structures of the submarine pyroclastic fan have been interpreted as the product of the interactions between pyroclasts, water waves and tsunamis induced by the ad 79 pyroclastic density currents into the Bay of Naples.