May
04
2009

East Coast tsunami threat or: Something to worry about other than the flu

A tsunami of New Yorkers head for the highlands.: Would the evacuation be this organized?
A tsunami of New Yorkers head for the highlands.: Would the evacuation be this organized?Courtesy Pabo76
What say we take a breather from all the bleak and uncertain flu news and turn our collective attention to the possibility of a tsunami washing away the East Coast of the USA? Fortunately no such threat is on the horizon at the present moment but scientists have found evidence they say indicates a large tsunami hit areas of New York and New Jersey some 2300 years ago.

The evidence includes large gravel, wood deposits, and marine fossils found in core samples across the region dating to 300BC, and suggests some sort of violent event took place in the region. The size and condition of some of the deposits point to strong reworking of material rather than just a single violent storm. The wave is estimated to have been 9 to 12 feet in height with the velocity of the water estimated at about a meter per second. If a similar tsunami hit Manhattan today no doubt there’d be big trouble.

But Atlantic tsunamis are rare events. Unlike the Pacific and Indian oceans where tectonic plates are colliding and earthquakes are more common, the plates along the Atlantic ridge are spreading apart. That’s not to say an Atlantic tsunami isn’t possible today. In 1929, a tsunami swept into the coast of Newfoundland killing more than two dozen people. The cause was a massive underwater landslide triggered by a 7.2 magnitude earthquake on the Grand Banks.

But neither an earthquake nor a submarine slump may have been involved in the 300BC tsunami. Recent research indicates an asteroid impact somewhere off the Atlantic coast dating to about the same time. Ejecta found in the local sediments such as spherules, shocked quartz, and nanodiamonds could only have been created under extreme temperatures and pressures produced by an extraterrestrial. No crater has been located as of yet but the scientists continue searching.

LINKS
BBC ancient tsunami story
More about the 300BC tsunami
East Coast tsunami threat considered in 2004

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