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Science Frontiers ONLINE No. 139: Jan-Feb 2002 |
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Surf's Up On California'S Shores: Really Up At Cortes Bank
The biggest waves swashing against southern California's beaches have grown by 2 meters or 35% since 1948.(Anonymous; "Surf's Up and Up and Up," New Scientist, p. 29, October 27, 2001.)
Comment. The Atlantic's waves, too, have been getting larger. (SF#113)
But if you want to surf some true Pacific giants, you must leave the shoreline and head for Cortes Bank 160 miles offshore. There, far out of sight of land, lurks a shallow rock shelf that amplifies wind-driven waves---but only the largest of them. The elliptical swirls of the smaller waves do not reach down to the rock shelf and are unaffected. But when bigger swells encounter the shelf they are amplified into giants.
So challenging are these waves that. when conditions are right, expert surfers boat out to Cortes Bank and wait for the really big ones.
Mike Parsons caught the first wave at dawn. It was 18 metres tall and moving at around 40 knots. You can't paddle fast enough to get onto a wave like that---you have to be towed by a jet ski. Evan Slater, editor of Swell.com, did try paddling onto a wave, but had to abandon his board and dive deep underwater to avoid being churned by the mammoth grinding walls of water.
18 meters is about 60 feet, but oceanographers calculate that an 18-meter wave is only 70% of what the Cortes Bank can generate. 25+ meters (80+ feet) is tops. (O'Hanlon, Larry; "California Screaming," New Scientist, p. 34, July 28, 2001.)
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