The tsunamis of Olympia

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The tsunamis of Olympia



Thursday, July 7, 2011  |  Featured, News

Olympia, the Sanctuary of Zeus and venue of the Olympic Games in Ancient Greece, was probably destroyed by tsunamis that reached far inland, and not as previously believed, by earthquakes and river flooding.

This is the latest theory put forward by University Prof. Dr. Andreas Vött from the Geographical Institute of the Johannes Gutenberg University in Mainz (JGU). Vött examined the site in the exploration of Paläotsunamis that have taken place over the last 11,000 years along the coasts of the eastern Mediterranean. The Olympic-tsunami hypothesis has been put forward due to sediments found in the vicinity of Olympia, which were buried under an 8 metres thick layer of sand and other debris, and only rediscovered around 250 years ago.

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Recovering the sediment sequences only a few hundred meters west of the Temple of Zeus. In the background is the mountain of Olympia, the Kronos hill. Image: © Andreas Vött/JGU

“The composition and thickness of the sediments we have found, do not fit with water flow of the river Kladeos and  geomorphological events such as earthquakes,” sad Vött. It was previously believed that an earthquake in 551 AD. destroyed the shrines and  afterwards floods from the Kladeos filled the ancient buildings.  However, Vött was puzzled that the small river Kladeos that flows past the Olympic site would need to have first been buried under several metres of sediment, in order to cut 10-12 metres deep at its ancient overflow level. In cooperation with the local Council of Antiquities and colleagues from the Universities of Aachen, Darmstadt, Freiburg, Hamburg and Cologne, Vött and his team researched extensively in the area using modern geomorphological geoarchaeological methods.

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Marine foraminifera. Image: Noora.S, Flickr

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The results suggest that the region was hit several times by major catastrophic floods and was covered by sediments in the past.  Mussel and snail shells and the remains of foraminifera (marine protozoa) clearly indicate a marine origin. The sediments must have arrived at speed from the coast towards Olympia which has an altitude of about 33 metres above sea level.

“Olympia is now 22 km from the sea, but previously the coast was at least 8 km, further inland,” explains Vött. In his scenario: tsunamis from the sea built up then ran into the narrow valley of Alpheus – which also includes the River Kladeos – with great force, and then rushed over the saddles in the range of hills that lie behind Olympia. The sanctuary then becomes flooded and the water flows slowly out, as the Alpheus valley is blocked by the incoming tsunami and its sediments. This suggests that in the context of deposited sediment sequences in the area, such a scenario has been repeated several times during the last 7,000 years; with one of the most recent events occurring  in the 6th Century AD. which carried with it the final destruction of Olympia.

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In support of the Olympic tsunami hypothesis is the fact that both on the sea facing side of the hilly terrain as well as in Olympia, identical high-energy sediments were found. “The deposits at Olympia have the same signature as the tsunami deposits upstream in the Alpheus valley,” said Vött. He ruled out an earthquake as the cause, as the fallen column drums of the Temple of Zeus  actually “float” in the sediment.  All sedimentological, geochemical, geomorphological and geo-archaeological findings support the new, sensational Olympic tsunami hypothesis.  Detailed analysis of faunal species composition, the origin and age of micro-organisms and age determination of sediments are being carried out, and these results will be available soon.

Tsunamis are a frequent occurrence in the eastern Mediterranean, which is mainly due to the high seismic activity along the Hellenic arc where the African plate pushes under the Eurasian plate, triggering strong earthquakes often with an accompanying tsunami. The last giant tsunami devastated coastal regions in 1908 after an earthquake in the Straits of Messina (southern Italy) where more than 100,000 people died. However, in the southern Aegean Sea in 1956, a 30 metre high wave was recorded. “An analysis of historical records has shown that in western Greece on average every 8-11 years, a tsunami occurred,” Vött confirmed.

For more information visit the Eastern Ionian Sea Tsunami Project website
Learn more

Geographical Institute of the Johannes Gutenberg University

Mamo, B. L.; Strotz, L. C.; Dominey-Howes, D.  Tsunami sediments and their foraminiferal assemblages, American Geophysical Union, Fall Meeting 2009

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Column drums from Temple of Zeus. Image: Templar1307, Flickr

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