Holiday hotspots could be devastated by a Mediterranean tsunami. Maps reveal 130 million lives at risk from once-a-century phenomenon
- Scientists modelled the effect of earthquakes off coasts of Sicily and Crete
- Large tsunami waves would spread across the Mediterranean in minutes
- The say up to 1.5 sq miles (3.8sq km) of Crete would be left under the water
- Large areas of densely populated coastline would be hit by the waves
A large tsunami in the Mediterranean could engulf many popular holiday hotspots and threaten the lives of 130 million people living along the sea's busy coastlines, a new study has revealed.
Researchers examining the impact of earthquakes off the north coast of Africa have simulated the impact of the devastating waves one might trigger.
They found that if an earthquake with a magnitude of 7.0 hit off the coasts of eastern Sicily in Italy and southern Crete in Greece, it would leave large areas of the coastline under water.
The research suggests some of the most densely populated parts of coastline in the region, many of which are popular holiday destinations, would be hit by the huge waves.
Their model additionally found that almost 1.5 square miles (3.8 sq km) of Crete would be lost to the ocean while the steeper cliff faces of Sicily would mean just 0.2 square miles (0.5 sq km) would be lost.
The Greek islands, which are popular with tourists and the coastline of Peloponnese would be particularly badly hit.
Researchers warn that while tsunamis in the Mediterranean are rare they tend to happen around once a century.
EUROPE'S BRUSH WITH TSUNAMIS
Tsunamis - the devastatingly huge waves caused by underwater earthquakes - are usually associated with coastlines of Japan or the Indian Ocean.
But new research proves that massive tidal waves sparked by seismic activity have also ravaged European shores in the past - and could be repeated.
Scientists from the University of Portsmouth found geological evidence that tsunami waves have swept over Malta's coastline - rising to up to 66ft (20 metres) above sea level in some places.
They identified 70-ton boulders inland that had been picked up from the seabed before being carried along by the huge waves and dumped far inland.
Studies of neighbouring coastlines show there has been a major tsunami, on average, every 400 years, thought to be linked to earthquakes beneath Mount Etna in Sicily, Italy.
The north-east coast is now Malta's most densely populated region and if a similar sized wave struck today, it could threaten thousands of people, experts are warning.
Many residents and holidaymakers live by or visit the north-eastern coasts, where the towns are built right up to the edge of the shoreline.
And they say larger earthquakes could trigger even more devastating waves, like the one that hit off the coast of Crete in 365AD with a magnitude of between 8 and 8.5.
The resulting tsunami destroyed ancient cities in Greece, Italy and Egypt, killing some 5,000 people in Alexandria alone.
More recently, an earthquake of magnitude 7 hit the Messina region in Italy in 1908, causing a tsunami that killed thousands, with waves exceeding 33ft (10 metres) in height.
Dr Achilleas Samaras, an engineer specialising in wave dynamics at the University of Bologna in Italy and lead author of the study, said: '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 main gap in relevant knowledge in tsunami modelling is what happens when tsunami waves approach the nearshore and run inland.
'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.
'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.'
The Mediterranean sits on the boundary where the African tectonic plate slides under the Eurasian plates.
The researchers studied the impact of an earthquake along the boundary between the African and Eursian plates that run under the Mediterranean Sea. They focused on quakes off the coast of Crete and Sicily, as can be seen in the map above, which shows the boundary of the plates
A tsunami off the coast of Sicily would send a wave radiating out but the islands high cliffs along its coastline would protect it from being badly inundated with water itself. However, as can be seen in the maps above, large parts of southern Italy and Greece would be hit with by waves within just minutes of an earthquake
Small earthquakes and tremors are common in the region, as are a handful of active volcanoes.
However, large earthquakes can occur if tension in the plates builds up and large slippages can trigger tsunamis that radiate out across the Mediterranean.
The researchers found that coastal areas where some 130 million people live would be at risk from such waves.
The researchers used land elevation to model how far the sea would inundate the coastline lines of Sicily (pictured top) and Crete (pictured bottom)
And they estimate water levels could rise by up to a 3ft (1 metre) with large waves in places where the water grew shallower.
There would also be little warning of such a tsunami as the distance they have to travel is small. Large parts of Libya's coastline would also be hit by the waves, they warned.
Within about 16 minutes, the simulations estimate the waves would have spread across much of the Mediterranean sea.
To study the impacts the team developed a computer model to represent how tsunamis in the Mediterranean could form, propagate and hit the coast.
They used information about the seafloor depth, shoreline and topography.
Dr Samaras said: 'We simulate tsunami generation by introducing earthquake-generated displacements at either the sea bed or the surface.
'The model then simulates how these disturbances - the tsunami waves - propagate and are transformed as they reach the nearshore and inundate coastal areas.'
'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.
'It is reasonable, however, to consider such results as indicative of how different areas in each region would be affected by larger events.'
The effects of an earthquake off the coast of Crete was more damaging due to its position in the eastern Meditteranean and lower coastline. Around 1.5 sq miles (3.8sq km) of land would be covered by water rushing in from the sea while the waves would hit southern Greece and parts of Turkey within minutes, as shown above
The researchers found low lying areas of coast in southwest Crete would be particularly vulnerable to tsunami waves (top left) while south east Sicily (bottom left) would be less prone due to the steep coastline. The pictures on the right show the height waves could reach off from a magnitude 7 earthquake