The geological record of storm events over the last 1000 years in the Salerno Bay (Southern Tyrrhenian Sea): new proxy evidences

Abstract

The shallow marine Late Holocene wedge of the northern Salerno Bay shelf (Southern Tyrrhenian Sea) discloses the presence of four decimetric shelf-tapering sand beds. Their internal features, depicted by cores analysis and their stratigraphic position, revealed by VHR seismic investigations, inferred sandy layers as being the result of flash deposition, storm controlled, thus episodic. Stratigraphic correlations among cores lead to constrain sandy layers deposition to storm events falling in the 11th, 16th, 19th and 20th centuries. A certain attribution of the most recent event bed to the major cloudburst that hit the Salerno region in 1954A.D. and resulted in a disastrous flood of the Bonea stream, was formerly achieved. A tentative link with two sea-storms that occurred in the 1544A.D. and in the 1879A.D. and well documented by historical sources is here proposed to explain the deposition of the two previous event beds. The deposition of these sandy layers must be related to major storm events, since their preservation in the stratigraphic record is not common. Lithostratigraphic and textural differences between flood and sea-storm emplacement emerge from the study of sandy layers in cores and point to a prevalence of sea-storm deposits in the middle shelf compared to flood deposits. Seismic stratigraphic evidence lead us to suppose that the style of episodic flash deposition has been running on for the last 2-3kyr and is probably linked to a climatic trend of the region.