Deep-sea tsunami deposits triggered by the explosion of Santorini (3500 y BP), eastern Mediterranean

The collapse of the Santorini caldera after the catastrophic eruption of the Bronze Age, 3500 y BP, caused a tsunami wave that had catastrophic effects in the Ionian basin, including its deepest parts. Pelagic turbidites of local origin were deposited on the bottom of small perched basins of the Southern Calabrian, Western and Central Mediterranean Ridges (type A homogenite) whereas a megaturbidite of distal origin, presumably triggered by the tsunami wave hitting the shoreline of the Sirte Gulf, was deposited on the Ionian and Sirte Abyssal Plains, extending eastwards as far as the Western Herodotous Trough depositing a thick, acoustically transparent layer (type B homogenite). Three core transects crossing the deformation front of the Mediterranean Ridge are presented and discussed. A fourth transect of giant piston cores was collected on the abyssal plains located to the south of the Mediterranean Ridge. All those to the west of the collision zone contain the Holocene homogenite with a thickness in excess of 20 m, whereas the cores taken from the Herodotous Abyssal Plain east of the collision zone are devoid of the homogenite. Sedimentological analyses were performed on the only giant core that penetrated the sandy base of the homogenite and the underlying pelagic sediments of late Pleistocene (last glacial) age. The African provenance of this typical type B homogenite is corroborated by shallow-water fauna derived from the North African shelf. No sedimentological characteristics peculiar to tsunamiites are observed in the deep-sea homogenite of the eastern Mediterranean.