Cracks in the North American continental shelf will have to be investigated further before it is known whether they are a potential threat to countries bordering, or surrounded by, the Atlantic.

Research begins this weekend on the newly discovered cracks in a 25 mile section of the shelf off the Virginia and North Carolina coasts.

One of the researchers has already been swamped with calls from concerned communities as far south as Florida.

Initial reports this week claimed the US Mid-Atlantic coast and the lower Chesapeake Bay would be at the highest risk for tsunami or tidal waves as tall as the storm surge of a category four hurricane, which is characterised by top sustained winds between 131 and 155 miles per hour.

Neal Driscoll of the Woods Hole Oceanographic Institution on Cape Cod, Jeffrey Weissel of Columbia University and John Goff of the University of Texas said the recently discovered cracks could mean the continental shelf is unstable.

The cracks indicate the sea floor could slide down like an avalanche, triggering giant waves. It's unclear whether the cracks are fossil features or whether they are still active, Mr. Driscoll said.

"The threat, if they haven't moved in a long time, might be less,'' he told the Associated Press. Yesterday when contacted by The Royal Gazette his office said he had been "swamped'' by media requests for comment on threats to local communities.

He said there is evidence that a tsunami, a massive wave caused by an earthquake or volcanic eruption, occurred 16,000 to 18,000 years ago.

A tsunami in Papua New Guinea killed 2,000 people in 1998.

Steve Blasco, a consultant to the Bermuda Underwater Exploration Institute and a marine geologist at the Canadian Geological Survey, said it was too early to tell if the Island should fear an attack.

"The potential effect is still unknown,'' he said. "With cracks like this you may have underwater landslides which may trigger tsunami.

"If they are not ancient they have a potential impact on Bermuda, yes, but so little is known. Nobody understands it yet, but it is an interesting question.''