Impact of Hellenic Arc Tsunamis on Corsica (France)

Abstract

In the historical period, the Eastern Mediterranean has been devastated by several tsunamis, the two most damaging were those of AD 365 and AD 1303, generated by great earthquakes of magnitude >8 at the Hellenic plate boundary. Recently, events of 6–7 magnitude have occurred in this region. As the French tsunami warning center has to ensure the warning for the French coastlines, the question has raised the possibility for a major tsunami triggered along the Hellenic arc to impact the French coasts. The focus is on the Corsica coasts especially, to estimate what would be the expected wave heights, and from which threshold of magnitude it would be necessary to put the population under cover. This study shows that a magnitude 8.0 earthquake nucleated along the Hellenic arc could induce in some cases a tsunami that would be observed along the Corsica coasts, and for events of 8.5 magnitude amplitudes exceeding 50 cm can be expected, which would be dangerous in harbors and beach areas especially. The main contribution of these results is the establishment of specific thresholds of magnitude for the tsunami warning along the French coasts, 7.8 for the advisory level (coastal marine threat with harbors and beaches evacuation), and 8.3 for the watch level (inland inundation threat) for tsunamis generated along the Hellenic arc.