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Tsunami (津波
Japanese big wave in port), often incorrectly called a
tidal wave, is a series of massive
waves that occur after an
earthquake,
seaquake,
volcanic activity,
slumps, or
meteorite impacts in or near the sea. The
energy of a tsunami is constant, a function of its height and speed.
Thus, as the wave approaches land, its height increases while its speed
decreases. The waves travel at high speed, more or less unnoticed where
crossing deep water, but increasing to a height of
30 metres and more. Tsunamis can cause severe destruction on coasts
and islands.
Many cities around the
Pacific, notably in
Japan but also in
Hawai'i, have warning systems and evacuation procedures in the event
of a serious tsunami. A tsunami would be predicted by various
seismologic institutes around the world and the progress monitored by
satellites.
Evidence shows that
megatsunamis, which are caused by significant chunks of an island
collapsing into the ocean, are also possible.
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