Possible strong earthquake in Crete would cause a devastating tsunami that could flood the coast at a depth of at least five meters, shows the model which was developed by European team with Greek participation.
The area south of Crete is highly seismic, as the island is located almost at the African and Eurasian tectonic plate. As the African plate moves north, sinks below the Eurasian plate and deforms the crust via powerful earthquakes.
10% of tsunami occurring around the world concerns about the Mediterranean, and one large tsunami happening in the region once every 100 years, says the group of Achilleas Samaras, a researcher at the University of Bologna who led the new study.
Such an event would be extremely destructive, as the Mediterranean coasts host around 130 million people. Moreover, the Mediterranean basin is relatively small which means that the tsunami waves need to travel only a very short distance before hitting the coast, reaching it with little advance warning.
In this study, it has been developed a model that simulates the birth and spread of a tsunami in the Mediterranean, based on data regarding the depth of the sea, the coastline and the terrain of the area.
"The main gap in relevant knowledge in tsunami modelling is what happens when tsunami waves approach the nearshore and run inland," says Achilleas Samaras. "We wanted to find out how coastal areas would be affected by tsunamis in a region that is not only the most active in the Mediterranean in terms of seismicity and tectonic movements, but has also experienced numerous tsunami events in the past."
The study simulates tsunami caused by an earthquake of magnitude of about 7.0 degrees that could hit the coast of eastern Sicily and southwestern Crete. In both cases, the waves would flood coastal areas and the tsunamis would inundate the low-lying coastal areas up to approximately 5 metres above sea level.
"Due to the complexity of the studied phenomena, one should not arbitrarily extend the validity of the presented results by assuming that a tsunami with a magnitude at generation five times larger, for example, would result in an inundation area five times larger," cautions Samaras. "It is reasonable, however, to consider such results as indicative of how different areas in each region would be affected by larger events."
"Although the simulated earthquake-induced tsunamis are not small, there has been a recorded history of significantly larger events, in terms of earthquake magnitude and mainshock areas, taking place in the region," says Samaras. For example, a clustering of earthquakes of magnitude of about 8.0-8.5 degrees, hit off the coast of Crete in 365 AD caused a tsunami that destroyed entire cities in Greece, Italy and Egypt- only in the city of Alexandria, the dead were estimated at around 5,000.
More recently, an earthquake of magnitude of about 7.0 degrees occurred in Messina, Italy in 1908, causing a tsunami that killed thousands. The testimonies speak of waves with a height of over 10 meters.
Better known, however, is the tsunami from the eruption of the volcano in Santorini at 16th century BC, one of the most powerful explosions in the history of mankind, which caused a tsunami that destroyed the Minoan civilization in Crete.
The statement of researchers says "Our simulations could be used to help public authorities and policy makers create a comprehensive database of tsunami scenarios in the Mediterranean, identify vulnerable coastal regions for each scenario, and properly plan their defence."
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