Sediment failure processes in active grabens: The Western Gulf of Corinth (Greece)

Abstract

On steep (2-6°) offshore fan deltas of Western Gulf of Corinth medium to small scale (106-107 m3) debris flows and avalanches are the prominent slope features. Loose sands, gravels and pebbles are observed in the lower fan while silty/sandy turbidites/tsunamites detected in cores, implying sediment dissociation during failure and downslope transport. These failures are associated with significant upslope retrogression that has caused coastal retreat with important human and economic impact. All the events were estimated to have occured during the late 4-5 kyr after or during the deposition (progradation) of the HST fan delta. Recent (late 0.1-0.15 kyr) prodelta failures in the Gulf of Corinth are evidenced by the destruction of telecommunication cables, coastal collapse and the initiation of destructive tsunami waves (i.e. 1963AD). The frequency of major failure events in the Western Gulf of Corinth is estimated to 2-3 events/0.1 kyr, usually associated with strong earthquakes and tsunamis (i.e. 1817, 1861, 1917?/,1963 1995AD events).