Echoes of past extreme wave events: Paleoenvironmental reconstruction in Vatika Bay, SE Peloponnese (Greece)

Situated in a tectonically active region, the Peloponnese is susceptible to large earthquakes, submarine landslides and volcanism, hazards capable of generating destructive tsunamis. Despite this, the triggering mechanisms and recurrence intervals of such events remain poorly understood. Coastal lagoons serve as valuable geoarchives, preserving the sedimentological footprints of such high-energy wave events. These fragile environments are highly sensitive to environmental and sea-level changes, making them ideal for reconstructing coastal dynamics.

Within the framework of the MULTI-MAREX project, this study investigates the sedimentary archives of Vatika Bay to identify traces of past marine geohazards. A multi-proxy approach was employed to analyze the sediments, including grain size, magnetic susceptibility, inorganic geochemistry and microfaunal composition.

Sedimentary records across the study area exhibit features of extreme wave deposits. These include abrupt changes in sedimentation with distinct coarser layers intercalated within muddy lagoonal and alluvial deposits, reflecting low-energy background sedimentation interrupted by an extreme marine incursion event. Sharp basal contacts and fining upwards sequences further support the marine origin of the deposits. Preliminary geochemical and foraminiferal analyses reveal delimited elevated concentrations and ratios for marine indicators, alongside sharp increases in foraminiferal assemblages, dominated by species typical of coastal environments.

Nevertheless, the shape and preservation potential of these deposits are influenced by the complex interplay between local tectonics, coastal morphology and lagoonal dynamics. Overall, this work provides new insights into the paleoenvironmental evolution of the coastal lagoon and its extreme wave event history, contributing to our understanding of marine geohazards in Greece.