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Ancient Tsunami Smashed Europe, Middle East, Study Says

James Owen
for National Geographic News
December 4, 2006
 
A massive tsunami smashed Mediterranean shores some 8,000 years ago when a giant chunk of volcano fell into the sea, researchers say.

Waves up to 165 feet (50 meters) high swept the eastern Mediterranean, triggered by a landslide on Mount Etna on the island of Sicily, according to the new study (see Italy map).

The research team says the natural disaster likely destroyed ancient communities, with a series of killer waves hitting the eastern Mediterranean coastline from Italy to Egypt.

Italian researchers based their findings on geological clues and evidence of a hastily abandoned Stone Age fishing settlement in Israel.

Maria Teresa Pareschi and colleagues at the National Institute of Geophysics and Volcanology in Pisa estimated the tsunami's strength by modeling the impact of the landslide from Etna, the tallest active volcano in Europe.

The team's calculation, published in the journal Geophysical Research Letters, shows that 6 cubic miles (25 cubic kilometers) of mountainside collapsed into the sea, generating giant waves that reached coasts as far away as the Middle East and North Africa.

The waves would have reached heights of about 165 feet (50 meters) off southern Italy, the team says, with a sea surge reaching 43 feet (13 meters) swamping parts of Greece and Libya.

Smaller waves hitting coasts farther away would also have had devastating power, according to Pareschi, who led the study.

"A tsunami wave height of a few meters can penetrate deeply inland," she said.

Long Waves

The team estimates the tsunami would have hit a maximum speed of around 450 miles an hour (725 kilometers an hour), taking a little over three and a half hours to reach what are now Israel and Egypt.

Evidence for the natural disaster comes mainly from disturbed sediments along the bottom of the Ionian Sea to the east of Sicily.

Tsunamis are known to destabilize soft marine sediments, the team notes, leaving telltale coverings of clay deposits after they reach land.

These deposits identify Mount Etna as the source of the tsunami and discount other possible causes, such as an asteroid strike or an undersea earthquake, the team says.

(See photos of Mount Etna.)

The researchers also speculate that a Neolithic village just off the coast of present-day Israel was hit by the tsunami.

The well-preserved Atlit-Yam settlement, which due to altered sea levels today lies submerged, "shows evidence of a sudden abandonment" 7,000 to 8,000 years ago, the researchers write.

These signs include a pile of gutted fish that had been processed and then "stored for future consumption," which was discovered buried under a layer of clay.

Secondary Tsunamis?

Further research by the Pisa-based team will investigate whether secondary tsunamis were set off by the sediment flows triggered by the initial tsunami from the Mount Etna collapse.

Pareschi said the probability of a new big collapse on Etna is low, but she added, "the eastern sector of the volcano is sliding toward the sea, and we have to understand very well the triggering mechanisms."

If the Etna tsunami had happened today, she said, the impact would be catastrophic, because the eastern Mediterranean coast is so densely populated.

(Read "Etna Volcano Becoming Dangerous, Experts Warn" [February 6, 2003].)

Some ten percent of tsunamis worldwide occur in the Mediterranean.

The most recent volcano-triggered tsunami was caused by a landslide on the Italian island of Stromboli in the Tyrrhenian Sea in 2002.

The volume of the landslide "was however a thousand times smaller than the Mount Etna one," Pareschi said.

A tsunami early warning system is currently being developed for the Mediterranean and the northeastern Atlantic. Due to become operational in December 2007, it will form part of a global tsunami warning system coordinated by the United Nations Educational, Scientific and Cultural Organization (UNESCO).

The measure follows in the wake of the devastating Indian Ocean tsunami, caused by an earthquake in December 2004, which struck coastlines with little or no warning.

(See "Tsunami in Southeast Asia: Full Coverage".)

Pareschi says the ancient Etna tsunami would have been comparable with the 2004 event, which claimed around 275,000 lives.

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