In search of Tsunami deposits along the eastern coast of Sicily (Italy): state of the art

Abstract

Eastern Sicily has been affected in historical times by large earthquakes followed by devastating tsunamis, such as the 1169, 1693 and 1908 events. In order to provide a long-term assessment for tsunami recurrence and related hazards, we developed a multi-disciplinary study, with a paleoseismo-logical approach, aimed to recognize and date historical and paleotsunami deposits. Starting from information on the effects of known tsunamis (hit localities, inundation areas, run-up heights) and with a geomorphological approach, we selected several sites—such as coastal lakes, marshes and lagoons—potentially suitable for preserving tsunami deposits. In these sites, 64 test gouge cores have been dug by hand and engine coring. In order to reconstruct paleoenvironments and to identify potential paleotsunami deposits, sedimentological and paleontological analyses were carried out. Magnetic and X-ray analyses were used to highlight susceptibility variations and peculiar small-scale sedimentary structures not detectable through the standard stratigraphic investigation. Moreover, radiocarbon dating and tephra identification provide age ranges of the tsunami deposits and constraints for sedimentation rates allowing the correlation with historical events. At Capo Peloro in northeastern Sicily, combining archaeological, historical, and C14 data, we associated two tsunami deposits with the earthquakes occurred in 1783 and 17 A.D. We also collected evidence for the occurrence of multiple inundations at sites in the eastern flank of Mt. Etna: three events in the past 580 yrs at the Anguillara site and four events in the past 4000 yrs at the Gurna site. In southeastern Sicily, in the Augusta bay, combining historical, tephrostratigraphical and C14 dating, we reconstructed a tsunami inundation history composed of six events in the past 4000 yrs; the two most recent ones are related to the 1693 and 1169 earthquakes.