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tsunami




Tsunamis are dramatic waves generated when a submarine earthquake causes a sudden shift in the ocean floor along a fault line.
Tsunamis are dramatic waves usually generated when a submarine earthquake causes a sudden shift in the ocean floor along a fault line.
tsunami
People run from an approaching tsunami in Hilo, Hawai'i, on 1 April 1946; note the wave just left of the man's head in right center of image. Credit: The Pacific Tsunami Museum in Hilo, Hawai'i
A Japanese word meaning "harbor wave." A tsunami is a wave or series of waves that are generated in a body of water by a sudden disturbance that displaces water. Found mainly in the Pacific, tsunami are typically caused by earthquakes and landslides in coastal regions. In mid-ocean, the wave height is usually under 1 meter, the distance between succeeding crests being of the order of 200 km, and the velocity about 750 km/h (400 mph). Near the coast, friction with the sea bottom slows the wave, so that the distance between crests decreases, the wave height increasing to about 25 meters or more.

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Map showing the hourly progression of a tsunami that originated just south of Alaska.
Map showing the hourly progression of a tsunami that originated just south of Alaska.

Volcanic eruptions, nuclear explosions, and even impact of meteorites, asteroids, and comets from outer space can also generate tsunamis.


Related categories

   • GEOGRAPHY
   • MEGACATASTROPHES

Source: U.S. Geological Survey