Paleotsunami deposits in the Augusta Bay area (Eastern Sicily, Italy): Preliminary results from offshore data

Twelve anomalous layers, marked by a high concentration of displaced epiphytic foraminifera (speciesgrowing in vegetated substrates like thePosidonia oceanica) and subtle grain-size changes were found in a6.7 m long,fine sediment core (MS-06), sampled 2 km off the shore of the Augusta Harbor (Eastern Sicily) at adepth of 72 m, recording the past 4500 yrs of deposition. Because concentrations of epiphytic foraminifera arequite common in infralittoral zones, but not expected at-72 m, we believe that these anomalous layersmight be related to the occurrence of tsunamis causing substantial uprooting and seaward displacement ofP. oceanicablades with their benthic biota.Our approach involved the study of geophysical data (morphobathymetry, seismic reflection, and seafloorreflectivity) and sediment samples, including X-ray imaging, physical properties, isotopic dating,tephrochronology, grain-size and micropaleontology.Correlations between anomalous layers and tsunami events have been supported by a multivariate analysison benthic foraminifera assemblage and dates of historical tsunami records. We found that four out of theeleven layers were embedded in age intervals encompassing the dates of major tsunamis that hit easternSicily (1908, 1693, and 1169) and the broader Eastern Mediterranean (Santorini at about BP 3600). One morelayer, even if less distinct than the others, was also defined and may be the evidence for the AD 365 Cretetsunami.© 2011 Elsevier B.V. All rights reserved