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.
|Tsunamis are dramatic waves usually generated when a submarine earthquake causes a sudden shift in the ocean floor along a fault line.
|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
|Map showing the hourly progression of a tsunami that originated just south of Alaska.
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Volcanic eruptions, nuclear explosions, and even impact of meteorites, asteroids,
and comets from outer space can also generate tsunamis.
Source: U.S. Geological Survey