Tsunami hazard regions in the Mediterranean region

Several devastating tsunami events have been documented for the Mediterranean in the last 2,500 years. Both earthquakes and volcano eruptions have triggered tsunami in this region in the past. The tectonic situation in the Mediterranean is complicated and detailed. Apart from the African Plate, which subducts beneath the Eurasian Plate, there are also microplates such as the Aegean and the Anatolian Microplate.

Along the Hellenic Arc the African Plate subducts beneath the Aegean Sea Plate. Earthquakes and volcano eruptions occur repeatedly along this subduction zone. In 1650 B.C., the eruption of the Thera volcano on the Greek island of Santorini triggered a tsunami – just like the earth­quake in the Aegean Sea in 1956.

However, not only in the eastern Mediterranean tsunami have been proven to have taken place in the past. Tsunami events are also documented in the western part of the Mediterranean. The last of these was in 2003, when the earth before the Algerian coast shook so strongly that waves up to two metres high caused a huge amount of property damage in the port of Palma de Mallorca. Due to the waves, several yachts were damaged, in some cases severely.

Tsunami hazard zones in the Mediterranean region

Scientists of the GFZ in Potsdam have divided the Mediterranean into 21 zones on the basis of historical data, for which they have entered earthquakes stronger than magnitude 5 together with tsunami events. From the historical data it can be quickly seen that, for example, both the western and eastern Hellenic Arc (see map, zones 14 and 19) are regions in which frequently strong earthquakes occured in the past.

In the event of an earthquake in the eastern Hellenic Arc there would remain 10 to 80 min­utes for a warning for Heraklion (Crete, Greece), for Athens (Greece) 60 to 160 minutes, and for Alexandria (Egypt) the warning time would be between 65 and 130 minutes. However, the hazard potential here would be significantly higher.