Tsunamigenic potential of a Holocene submarine landslide along the North Anatolian Fault (northern Aegean Sea, off Thasos island): insights from numerical modelling
Résumé
The North Anatolian Fault in the northern Aegean Sea triggers frequent earthquakes of magnitudes up to Mw∼7. This seismicity can be a source of modest tsunamis for the surrounding coastlines with less than 50 cm height according to numerical modelling and analysis of tsunami deposits. However, other tsunami sources may be involved, like submarine landslides. We assess the severity of this potential hazard by performing numerical simulations of tsunami generation and propagation from a Holocene landslide (1.85 km3 in volume) identified off Thasos. We use a model coupling the simulation of the submarine landslide, assimilated to a granular flow, to the propagation of the tsunami wave. The results of these simulations show that a tsunami wave of water height between 1.10 and 1.65 m reaches the coastline at Alexandroupoli (58 000 inhabitants) 1 h after the triggering of the landslide. In the same way, tsunami waves of water height between 0.80 and 2.00 m reach the coastline of the Athos peninsula 9 min after the triggering of the landslide. Despite numerous earthquakes of Mw>7 and strong detrital input (on the order of 30 cm ka-1), only a few Holocene landslides have been recognized so far, asking for tsunami recurrence in this area.
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