Millennial variability of rates of sea-level rise in the ancient harbour of Naples (Italy, western Mediterranean Sea)

We reconstructed the late Holocene relative sea-level (RSL) evolution of the ancient harbour of Naples, one of the largestcoastal conurbations in the Mediterranean. We carried out multiproxy investigations, coupling archaeological evidencewith biological indicators. Our data robustly constrain 2000 yr of non-monotonic changes in sea level, chiefly controlledby the complex volcano-tectonic processes that characterize the area. Between∼200 BC and AD∼0, a subsidence rateof more than∼1.5 mm/yr enhanced the postglacial RSL rise, while negligible or moderate land uplift <∼0.5 mm/yr triggereda RSL stabilization during the Roman period (firstfive centuries AD). This stabilization was followed by a post-Romanenhancement of the sea-level rise when ground motion was negative, attested by a subsidence rate of∼0.5 to∼1 mm/yr.Our analysis seems to indicate very minor impacts of this nonmonotonic RSL evolution on the activities of the ancient har-bour of Naples, which peaked from the third century BC to the second century AD. After this period, the progressive silting ofthe harbour basin made it impossible to safely navigate within the basin, leading to the progressive decline of the harbour