NORTHAMPTON, Mass (Reuters) - A U.S.-led research team may have finally located the lost city of Atlantis, the legendary metropolis believed swamped by a tsunami thousands of years ago in mud flats in southern Spain.

"This is the power of tsunamis," head researcher Richard Freund told Reuters.

"It is just so hard to understand that it can wipe out 60 miles inland, and that's pretty much what we're talking about," said Freund, a University of Hartford, Connecticut, professor who lead an international team searching for the true site of Atlantis.

To solve the age-old mystery, the team used a satellite photo of a suspected submerged city to find the site just north of Cadiz, Spain. There, buried in the vast marshlands of the Doñana Park, they believe that they pinpointed the ancient, multi-ringed dominion known as Atlantis.

The team of archeologists and geologists in 2009 and 2010 used a combination of deep-ground radar, digital mapping, and underwater technology to survey the site.

Freund's discovery in central Spain of a strange series of "memorial cities," built in Atlantis' image by its refugees after the city's likely destruction by a tsunami, gave researchers added proof and confidence, he said.

Atlantis residents who did not perish in the tsunami fled inland and built new cities there, he added.

The team's findings will be unveiled on Sunday in "Finding Atlantis," a new National Geographic Channel special.

While it is hard to know with certainty that the site in Spain is Atlantis, Freund said the "twist" of finding the memorial cities makes him confident Atlantis was buried in the mud flats on Spain's southern coast.

"We found something that no one else has ever seen before, which gives it a layer of credibility, especially for archeology, that makes a lot more sense," Freund said.

Greek philosopher Plato wrote about Atlantis some 2,400 years ago, describing it as "an island situated in front of the straits which are by you called the Pillars of Hercules," as the Straits of Gibraltar were known in antiquity. Using Plato's detailed account of Atlantis as a map, searches have focused on the Mediterranean and Atlantic as the best possible sites for the city.

Tsunamis in the region have been documented for centuries, Freund says. One of the largest was a reported 10-story tidal wave that slammed Lisbon in November, 1755.

Debate about whether Atlantis truly existed has lasted for thousands of years. Plato's "dialogues" from around 360 B.C. are the only known historical sources of information about the iconic city. Plato said the island he called Atlantis "in a single day and night... disappeared into the depths of the sea."

Experts plan further excavations at the site where they believe Atlantis is located and at the mysterious "cities" in central Spain 150 miles away to more closely study geological formations and to date artifacts.

(Editing by Barbara Goldberg and Greg McCune)

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