A tsunami (plural:
tsunamis or tsunami; from Japanese: 津波, lit. "harbour wave";[1] English pronunciation: /suːˈnɑːmi/ soo-nah-mee
or /tsuːˈnɑːmi/ tsoo-nah-mee[2]) is a series of water waves
caused by the displacement of a large volume of a body of water, generally an
ocean or a large lake.
Earthquakes, volcanic eruptions and
other underwater
explosions (including detonations of underwater nuclear devices),
landslides, glacier
calvings, meteorite
impacts and other disturbances above or below water all have the
potential to generate a tsunami.[3]
Tsunami waves do not resemble normal sea waves, because their
wavelength is far longer. Rather than appearing as a breaking wave, a tsunami
may instead initially resemble a rapidly rising tide, and for this reason
they are often referred to as tidal waves. Tsunamis generally consist of
a series of waves with periods
ranging from minutes to hours, arriving in a so-called "wave train".[4] Wave heights of tens of
metres can be generated by large events. Although the impact of tsunamis is
limited to coastal areas, their destructive power can be enormous and they can
affect entire ocean basins; the 2004 Indian
Ocean tsunami was among the deadliest natural disasters in human
history with over 230,000 people killed in 14 countries bordering the Indian Ocean.
The Greek historian Thucydides suggested in
his late 5th century BC, History of
the Peloponnesian War, that tsunamis were related to submarine
earthquakes,[5][6] but the understanding of a tsunami's nature
remained slim until the 20th century and much remains unknown. Major areas of
current research include trying to determine why some large earthquakes do not
generate tsunamis while other smaller ones do; trying to accurately forecast
the passage of tsunamis across the oceans; and also to forecast how tsunami
waves would interact with specific shorelines.
A tsunami is usually caused by a powerful
earthquake under the ocean floor. This earthquake pushes a large volume of
water to the surface, creating waves. These waves are the tsunami.
In the deep ocean these waves are small. As they
approach the coast these waves get bigger and more dangerous. Tsunami waves can
cause tremendous damage when they reach land.
A tsunami can also be triggered by a volcanic
eruption, landslide, or other movements of the Earth’s surface.
resource : http://en.wikipedia.org/wiki/Tsunami
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