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TSUNAMIS
Tsunamis are seismic sea
waves. The word tsunami is Japanese meaning harbor wave. The majority of waves
at sea are generated by the wind. Yet, tsunamis form after some sort of displacement
of the earth beneath the ocean - as in an earthquake. They are a very deep wave,
extending from the sea surface down to the ocean floor and can move the entire
vertical section of ocean through which it travels. The greater the water depth,
the faster the tsunami travels - some up to 600 mph.
A tsunami has a long wavelength. Usually, a tsunami consists of a series of
waves which can span several hundred miles between crests. Strangely enough,
these enormous waves can hardly be seen or felt by ships on the open seas. But
as it approaches land, a tsunami slows down as the bottom of the wave drags
on the sea floor, causing a crest to rise rapidly and crash tons of water upon
the shore.
The most active area for
earthquakes and tsunamis is within the Pacific Ring of Fire. Damaging tsunamis
are rather rare along the West Coast of the United States, yet the threat is
always present. One memorable, but destructive tsunami wrecked havoc on Crescent
City, California over 30 years ago, in March of 1964.
Since that time, a Tsunami
Warning Service, centered in Alaska and Hawaii, has been established to send
timely warnings to the coastal areas across the Pacific Ocean and the world.
Any tsunami warning that is issued, is then broadcasted on the NOAA Weather
Radio.
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