A 40m sea monster, just like the old salts said
June 16, 2005
LOS ANGELES: When seafarers described giant freak waves in tones of awe, sceptical landlubbers dismissed them as fantasy. Now scientists believe they have evidence of a wave the size of a 10-storey building.
It happened on September 16 last year when Hurricane Ivan stormed across the Gulf of Mexico and tore into the coast of Alabama, accompanied by 210km/h winds and storm surges more than 2m high.
While still out at sea, oceanographers report, the hurricane also produced a series of giant waves, one of which stood 28m from crest to trough, a new world record for a wave.
But science, like old salts' tales, is fallible. The seabed instruments that measured the surge were turned off at the moment the winds reached their peak, and scientists from the Naval Research Laboratory at Stennis Space Centre, Mississippi, had to employ a computer model to predict that, while they were not looking, at the height of the storm the wave reached 40m. By comparison, the tsunami that swept across the Indian Ocean in December stood about 9m high as it hit shorelines, although in some parts of Indonesia it was reported to have reached 20m.
The greatest wave of all is not yet upon us. Scientists predict that if a future volcanic eruption sends a large part of the island of La Palma in the Canaries into the sea, it could cause a wall of water 900m high. Reassuringly, they do not expect it this century.
The previous record for a wave was 26m, measured by the ocean weather ship Weather Reporter in the Atlantic on December 30, 1972.
Giant waves are difficult to record because buoys on the surface of the sea are usually wrecked by the intense storms. Luckily, the eye of Hurricane Ivan passed over 14 water pressure sensors spread over 61km of seafloor 160km off the Alabama coast.
The sea currents generated by the hurricane broke another world record: the maximum current on the sea floor was 2.25m/s compared with the Gulf Stream, which reaches top speeds of about 1.5m/s.
The hurricane caused the deaths of 116 people across the Caribbean.