Risk description

Mediterranean coasts are exposed to tsunami risk, not only for the high seismicity of the area, but also for the presence of various volcanoes, both emerged and submerged. However, if a  tsunami occurred in the Mediterranean Sea - a closed and quite shallow basin - it would not be as intense as one developing in the Oceans, where earthquakes with higher magnitude than the ones of the Mediterranean area can occur and water masses are much greater. Nevertheless, history has demostrated that, following very energetic seismic events or submarine landslides, destructive tsunamis can occur, also due to the high urbanization of the coastal areas.

The tsunami is a rapid rise of the sea level, exactly like a water wall that sweeps down coasts, causing an inundation that floods the coastal belt. Sometimes an initial and sudden withdrawal of the sea can be observed, leaving dry ports and coasts. Tsunami waves have a much greater force than sea storms and are able to move inland for hundreds of meters (even kilometers, if the coast is very low), dragging everything along the path: vehicles, boats, trees, and other material, which increases the destructive potential.

Propagation and effects of the wave on the coast are affected by morphological factors – such as the shape of the coast or the topography of the sea bed and of the hinterland – and anthropic factors, linked to the use of the soil. The structure of port areas, for example, may amplify the energy of the tsunami, whereas the presence of buildings and docks along the coast can reduce the inland propagation of the wave. Tsunami waves can also climb up from the outlets of rivers and streams, propagating inland along their flow.

Besides the effects linked directly to the action of the moving wave, a tsunami can trigger a series of secondary effects: the inundation can in fact cause landslides, groundwater pollution, or fires. The impact on ports and industrial plants can cause the emission and diffusion of polluting substances.