Though Hurricane Bill did not make a direct hit on the U.S. East Coast, its wave-making power was made clear Sunday when a surprisingly large wave, termed a "rogue wave" by the Portland Press Herald, struck Acadia National Park. A 7-year-old girl was killed, and three other people had to be pulled from the water.

Scientists don't fully understand how unusually large waves can suddenly emerge among smaller ones. But a study last year revealed one way:

Normally a large wave on the open ocean breaks into smaller waves, in a dampening effect caused by interaction with other waves. But lab tests showed that the opposite can occur: Small waves can join forces to become monsters "that emerge surprisingly quickly," explained researcher Peter McClintock, a physicist at the University of Lancaster in England.

Sunday's killer wave got an assist from an above-average high tide and Hurricane Bill's storm surge, which piled water near the coast to put otherwise high-and-dry locations at risk. How exactly the surprisingly large wave formed remains unknown, however.

Interestingly, a series of mysterious, 12-foot waves — which had the look of tsunami waves — struck Maine's Boothbay Harbor last October.

Source : LiveScience