Boulders transport by catastrophic waves along the Ionian coast of Apulia (southern Italy)

Abstract

Several tracts of the Ionian coast of Apulia (southern Italy) are characterized by large boulders, up to 80 t in weight, scattered some meters above present sea level. The largest boulder is about 80 t in weight and slid for about 40 m from the mean sea level up to about 1.8 m of altitude. Elongated boulders show a remarkably narrow range of orientation of the long axis as well as of the imbrication axis, suggesting that they had been transported by a single catastrophic event, most likely a tsunami, connected to a wave train approaching the coast from the South. Stratigraphic, morphological and historical data suggest that this event occurred during the late Holocene. Conventional radiocarbon age determination performed on Lithophag shells collected from a large boulder yielded a calibrated age between 1421 and 1568 A.D. Then, the catastrophic wave train, probably a tsunami, could be a local effect of the strong earthquake which hit southern Italy on December 5th, 1456.