In search of tsunami deposits along the eastern coast of Sicily (Italy): the 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 hazard, we developed a multi-disciplinary study, with a paleoseismological approach, aimed to recognize and date historical and paleo-tsunami 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 paleo-tsunami 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 trough the standard stratigraphic analysis. Moreover, radiocarbon dating and tephra identification provide age ranges of the tsunami deposits and constrains for sedimentation rates allowing the correlation with historical events. At Capo Peloro in north-eastern Sicily, combining archaeological, historical, and C14 data, we associated two tsunami deposits, to the 1783 and 17 A.D. earthquakes. We collected also evidence for the occurrence of multiple inundations at sites in the eastern flank of Mt Etna: three events in the past 580 yr at Anguillara site and four events in the past 4000 yr at Gurna site. In south-eastern 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 yr, the two most recent ones are related to the 1693 and 1169 earthquakes.