Many tsunamis documented in the Mediterranean region are caused by strong earthquakes occurring in the area offshore Crete Island, one of the most active seismic areas in the Euro-Mediterranean region known as the West Hellenic Arc and Trench (WHA-T) system. The largest tsunami event ever occurred in the Mediterranean Sea, which devastated Alexandria in Egypt and caused important damages also on the Sicilian and Croatian coasts, originated in AD 365 from an earthquake in West Crete. When is next strong tsunami originating from this source due to happen?
WHA-T starts from Zakynthos Island to the North and ends to the eastern part of Crete. Localities reported on the map were associated with tsunami inundations.
A research by the Institute of Geodynamics, National Observatory of Athens on ”Tsunami hazard in the eastern Mediterranean Sea: strong earthquakes and tsunamis in the West Hellenic Arc and trench system” collected data on earthquake and tsunami occurred in the WHA-T area, investigated the average recurrence of strong tsunamis and performed probabilistic tsunami hazard assessment.
Statistical analysis indicated that tsunamis of low or moderate intensity recur every few years, which means rather frequently. Strong tsunamis, however, are rare. The average recurrence of devastating tsunamis like the one of 365 AD resulted of the order of 1277 years.In reality – researchers say - the last tsunami event of this intensity occurred in the West Hellenic Arc in 365 AD. The actual time elapsed from the last event is equal to 1643 years. Then, the frequency of occurrence of large-size tsunamis seems significantly overestimated by the intensity-frequency statistics and thus not so reliable. The research concludes that the number of tsunami events considered in the statistical analysis is very small, thus making the statistics extremely sensitive, particularly for large-size events which are of very low frequency. Therefore large tsunamis result to be more and more unpredictable.
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