Witold Skrypczak/Getty Could Geneva's spectacular lakefront be hit by a tsunami?

Related A Tsunami in Switzerland? Lake Evidence Says Yes New York Times

Ah, Geneva — a place where you can stroll along the lakefront, gaze at Mont Blanc and, according to scientists, be bowled over by a giant tsunami.

Researchers say they’ve found good evidence that it has happened before. In the sixth century — the age of King Arthur, Mohammed and the bubonic plague — a bishop named Gregory of Tours noted an unusual event in Geneva. In 563, he wrote, a cascade of rocks plunged into the Rhone River, generating a wave of water that “overwhelmed with a sudden and violent flood all that was on the banks as far as the city of Geneva,” over 40 miles away, according to the New York Times.

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Historians reading Gregory’s story, which is backed up by other ancient texts, have suspected for quite some time that something akin to a tsunami had hit Lake Geneva.

Now, there may be science to prove it. On the bottom of the lake, nearly 1,000 feet down, researchers from the University of Geneva have discovered a massive, 16-foot deep deposit of sediment, six miles long and three miles wide. Taking samples from bits of wood and leaves stuck in the sludge, the scientists concluded that the sediment dates from between the late fourth and early seventh century. They suspect this may have been what was left of the rocky mass that Gregory reported nearly 1,500 years ago. Using computer simulations, they estimate that the effect of that much material plunging into the water would have caused a 26-foot high tsunami wave which would have reached Geneva in about 70 minutes.

What caused the rocks to fall into the river in the first place? It may have been an earthquake, say scientists. They also say lakeside dwellers should wipe that smug, not-tsunami-fearing look off their faces. “People think, ‘Oh, lucky us, we live near a lake — we don’t have any such threat,’ ” Dr. Guy Simpson of the University of Geneva told the New York Times. “This reminds people that hey, hang on, these things have happened in the past, and quite likely will happen again.”

Head on over to the New York Times website to check out a graphic illustrating how the Swiss tsunami may have unfolded. You can also listen to an interesting discussion with the article’s author, Henry Fountain, and find out what became of 6th century Geneva.

If you’re looking to bone up on ancient natural disasters, here’s a primer on a few lesser-known ones:

1. The Plague of Justinian

In 541-542 A.D., a tiny bacteria swept across the ancient world, killing as many as 100 million people. It’s named after Justinian, emperor of the Eastern Roman Empire at the time, who contracted the disease but did not die from it. We can all give thanks to Alexander Fleming for discovering that little mold penicillin in 1928 and ensuring this (probably) won’t happen again.

2. The Antioch Earthquake

The 6th century was not a great time for humanity in general. In 526 A.D., a devastating earthquake struck the city of Antioch, in present-day Turkey, killing some 250,000 people. The quake lifted the city’s port up by more than three feet and caused fires to break out, destroying what remained of the metropolis. Antioch, once a great outpost of the Byzantine Empire, was reduced to rubble in the disaster.

3. The Alexandria Tsunami

On July 21, 365 A.D., a magnitude 8.0 quake hit the island of Crete, generating a tsunami that swept across the Mediterranean towards the port city of Alexandria. The water pushed the port’s giant ships inland into the city and deposited them on top of buildings. Tens of thousands of people lost their lives.

4. Damghan Earthquake

This earthquake hit modern-day Iran on Dec. 22, 856 A.D., causing some 200,000 deaths, including 45,000 in the Persian city of Damghan.

5. Plague of Athens

During the Peloponnesian War (431-404 B.C.), Athens was struck down by a plague which may have wiped out as much as a third of the city-state’s population. Historians debate whether the epidemic contributed to Athens’ loss of the war to Sparta and the Peloponnesian league. In the city-state itself, however, the plague had a number of well-documented social effects. The Greek historian Thucydides recorded that it changed peoples’ attitudes toward the social order and money — with citizens spending and breaking the law with impunity.

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