Back in 2001, the cruise ship Caledonian Star, returning from a voyage to the Antarctic coast, suddenly found itself in a fierce storm. As the ship's first officer stood evening watch, he was astonished to see an enormous wave rise from the sea toward him.
As recounted in the 2006 book "Extreme Waves," the officer recalled being engulfed by a wall of water that shattered the ship's windows and flooded the bridge, 100 feet above the waterline. Fortunately, he and the ship's helmsman were able to swim back to the ship's controls, and the Caledonian Star eventually made it home safely.
Over the centuries, there have been plenty of other mariners' accounts of such rogue waves - quick-rising, towering walls of water capable of battering even the biggest ships into oblivion. The stories sometimes have been discounted by oceanographers, who insisted that big ocean waves build up gradually and have relatively narrow crests.
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But now, University of Oxford and University of Australian researchers have created a mathematical model that shows how monster waves could suddenly arise after a series of smaller waves.
The study, published in Proceedings of the Royal Society A, used simulations of hundreds of waves to come to its conclusion.
"The waves we're dealing with here occur in deep water in the open ocean - very different from the waves you'll see if you go to the beach, which is what most people are familiar with," Oxford engineering professor Thomas Adcock explained in a press release.
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"In deep water, where waves are much less regular, you expect a larger wave from time to time," Adcock said. "Our paper shows that, in contrast to what was previously thought, if you're the observer on a ship, rather than seeing a gradual build-up of waves, the rogue wave will come seemingly out of nowhere. This happens because large waves tend to move to the front of the wave group."
The study offers a warning to ships and their crews. "All of this means that in a very rough storm, you can't simply assume you'll get a warning before a freak wave hits," Adcock said. "Seafarers need to be aware that a large wave may appear out of nowhere."