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ipacific

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Rogue waves no fairytale
« on: March 05, 2010, 08:30:32 AM »
Rogue wave strikes cruise ship

Rogue waves strikes more often than thought

It was like something out of a Hollywood disaster movie. On March 3, 2010 a cruise ship Louis Majesty sailing in the Mediterranean Sea off the northeastern coast of Spain was hit by a sudden wall of water, killing two people, injuring 14 and causing severe damage to the vessel.
According to Louis Cruise Lines, the owner of the vessel, the Louis Majesty, it was hit by three "abnormally high" waves, each more than 33 ft. (10 m) high, striking in clear weather and without warning.

The Louis Majesty wasn't hit by a sudden storm, or any of the other expected dangers of maritime travel. Rather it may have been the victim of rogue waves. For centuries mariners have told stories about sudden waves that would emerge out of the open ocean without warning, strong enough to topple even large ships. The SS Waratah, which vanished on a journey to Cape Town; the MS Munchen, lost en route to Savannah; even the SS Edmund Fitzgerald, "the good ship and true" of the Gordon Lightfoot song, which disappeared on Lake Superior — all were rumored to be sunk by rogue waves.

Until recently, however, marine scientists dismissed rogue waves as little more than a sailors' fantasy, with reason — there was little evidence to back them up. But in 1995 an oilrig in the North Sea recorded a 25.6 m-high wave that appeared out of nowhere, and in 2000 a British oceanographic vessel recorded a 29 m-high wave off the coast of Scotland. In 2004 scientists from the European Space Agency (ESA), as part of the MaxWave project, used satellite data to show that freak waves, higher than 10 stories, were rare but did occur on the oceans.

Scientists still don't know exactly how rogue waves occur, nor do they know how to predict them. Open ocean waves, possibly including rogue waves, form when wind produces distortion over the surface of the sea — the stronger the wind, the higher the wave, which is why hurricanes can create such destructive walls of water. Tsunamis, on the other hand, like the one produced by the 8.8-magnitude earthquake in coastal Chile on Feb. 27, don't create rogue waves; tsunamis barely make a ripple on the open ocean, and only gather in size when they reach shallow land near a coastline.

Rogue waves generally occur out in the open ocean. They may be the result of a number of factors coming together — strong winds and fast currents coinciding, for instance — or of a focusing effect, where several smaller waves join together to form one big wave. There may even be a non-linear effect at work, in which just a small change in wind speed multiplies to form a big wave. And certain areas of the ocean, like the strong waters off Africa's coast, may be more vulnerable to rogue waves than others.

Creating artificial rogue waves in a laboratory has always been a challenge. But in 2009, scientists from Harvard University and Tulane University examined patterns of microwaves, rather than water waves, to get a better sense of how rogues might arise. They created a metal platform in a lab measuring 26 cm by 36 cm, and randomly placed 60 small brass cones on the platform, to mimic the effect of unexpected ocean eddies in the current. When they beamed microwaves at the platform, the scientists found that "hot spots" — the microwave equivalent of rogue waves — appeared as much as 100 times more often than standard wave theory would predict. Those results indicate that rogue waves might be a lot more common than scientists had believed, and could explain why so many large ships — as many as two a week — sink even in the absence of bad weather. One day we might even be able to predict when these earthquakes of the sea occur — sparing future cruisegoers from the trauma suffered by those on the Louis Majesty.


Read more: http://www.time.com/time/health/article/0,8599,1969845,00.html

ipacific

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Re: Rogue waves 'wipe out' spectators at surfing competition
« Reply #1 on: March 05, 2010, 09:00:41 AM »
Rogue waves 'wipe out' spectators at Mavericks surfing competition



They were there to watch some of the world’s top surfers take on some of the biggest waves, but hundreds of spectators did not expect to become part of the action.

Two walls of water swept dozens of people off a concrete seawall where they had gathered to watch a surfing competition at Mavericks Beach near San Francisco in California yesterday.

At least 13 spectators received significant injuries, including broken legs and hands, when the crowd was knocked off the wall by 6ft-high waves, which smashed onto the beach, wiping out a marquee and throwing spectators on to rocks. Others escaped injury by scattering to higher ground.

At least three people were taken to hospital, and others were treated at the beach for minor injuries.

Scott Jalbert, the local fire chief, said that a couple of hundred people were on the seawall at the time of the accident. He estimated the waves reached up to 6ft high when they struck the beach, describing them as “small, but strong”.

“It's a force of nature that can't be predicted,” Mr Jalbert said. “We were very lucky that nobody was swept out to sea.

“Nobody was swept away into the water. They were just swept onto the beach area pretty hard. It's pretty rocky.”

Earlier hundreds of spectators had climbed a nearby hill to watch the competition. However, the view was obscured by fog so dozens had swamped the beach for a closer look and to watch the action on a big screen which had been erected on the shore.

Marsha Poulin was at the water's edge minutes before the first wave struck. She said she was concerned that organisers had let spectators get so close to the ocean, given the conditions.

“Just because they were letting us be here doesn't mean it was safe,” said Ms Poulin, who left for higher ground just in time.

“It just came out of nowhere and wiped us all out,” said Pamela Massette, who scraped her hand when she was hit by the waves.

The surfing contest offers a $150,000 (£96,000) first prize, making it the most lucrative big-wave contest in the world.

Surfers said the conditions were ideal for big-wave competition, with some estimating the waves had reached up to 50ft offshore.

Ion Banner, a surfer who took part in the competition, said that the waves were “consistently bombing”, and were the biggest waves he had seen at a Mavericks contest.

"It was crazy, super-big and pretty much the real deal," Mr Banner told the San Francisco Chronicle.

http://www.timesonline.co.uk/tol/news/world/us_and_americas/article7026544.ece

 


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