Sedimentary geochemical evidence of historical tsunamis in the Eastern Mediterranean from Ölüdeniz Lagoon, SW Turkey

Abstract

In the Eastern Mediterranean and southern Aegean seas, historical records indicate there were 17 tsunamis in the last 2500 years with intensities > 6 on a 12-point tsunami intensity scale. Regional geologic records of past tsunamis, however, are not sufficiently well-documented to assess tsunami hazards. This study presents geochemical evidence of historic tsunamis in the Eastern Mediterranean for the last 700 years, detected in the sedimentary sequence of Oludeniz Lagoon, SW Turkey. Sediment chronology was established by 137Cs and 210Pb dating, and regional chronostratigraphic correlation reveals that three events observed within the sequence correlate temporally with the AD 1303, 1609, and 1741 tsunamis in the region. The sediment anomalies (tsunami deposits) appear as reddish-brown intercalations within yellowish-brown background sediments of the lagoon, and are enriched in K, Ti, Fe and Zn, but depleted in Ca. This kind of geochemical fingerprint is attributed to a sudden increase in the input of terrigenous sediment to the lagoon, which was swept from Oludeniz beach and the sand spit of the lagoon by marine overwash during tsunamis. If the stratigraphic thickness and magnitude of the geochemical anomalies are assumed to be a proxy for tsunami intensity, then the AD 1609 event was stronger in the Oludeniz region than the AD 1303 and 1741 tsunamis.