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Tsunami
By Alexandra Busato
April is Tsunami Awareness Month!
Origin of the word
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Tsunami is a Japanese word. Tsu means "harbor", and nami means "wave". Tsunami are
common in the history of Japan. There have been almost 200 so far in Japan that have been
recorded. The Greeks were writing about it in 426 B.C.
Tsunami warning sign
on a seawall in Japan
How a tsunami is formed
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A tsunami is a series of huge waves
caused by a disturbance undersea,
usually earthquakes, but also landslides,
volcano eruptions or meteorites.
A tsunami can move hundreds of miles
per hour in the open ocean and smash
into the land with waves as high as 100
feet or more.
Tsunamis are hard to notice while they
are in the water. They have a small wave
height (amplitude), and a very long
wavelength. They only grow in height as
they reach the shore. This is called
shoaling.
What a tsunami is like
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The waves travel in all
directions, like the
ripples you get after
throwing a rock. They
can cause a lot of
destruction on the
shore.
Sometimes, there is
more than one wave,
and the one that comes
after could be larger.
They are sometimes
called "tidal waves," but
tsunami have nothing to
do with the tides.
Boxing Day Tsunami in Thailand, 2004
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This is a map of tsunamis that have happened in the world. There have been almost 2000
tsunamis so far. The size of circle is proportional to the magnitude. Red is for tsunamis that
only happened in oceans, purple is for regional tsunamis that caused deaths, and blue is for
all other tsunamis.
About 80% of all tsunamis occur in the Pacific Ocean, but they are possible wherever there
is a large body of water. Tsunami are not rare. There were at least 25 in the last century.
Many were recorded in the Asia–Pacific region, especially in Japan.
A tsunami can strike anywhere on most of the U.S. coastline. Hawaii is the state with the
most tsunamis. They get about one a year.
Dangers
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All tsunamis can be dangerous. Deaths
are usually caused by drowning.
The tsunami waves and the receding
water can destroy buildings in its path.
There is also the danger of flooding,
water being contaminated, and fires
being started from ruptured gas lines or
tanks.
Houses in Sumatra in Indonesia, flooded by the
Boxing Day Tsunami of 2004.
Famous Tsunami
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In 1946, there was an earthquake in
Alaska, that started a tsunami which
flooded Hilo on the island of Hawaii with
waves of 20 to 32 feet.
On December 26, 2004, the Boxing Day
tsunami in the Indian Ocean killed over
300,000 people, and injured many more.
When the sea pulled back, many people
went on the shore to investigate and most
of them died.
This photo was taken when the Boxing
Day tsunami hit Thailand on December
26, 2004
Boxing Day Tsunami in Thailand, 2004.
Signs of an approaching tsunami
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A tsunami cannot be prevented or
predicted, but there are warning signs. If
there’s an earthquake near a body of
water, it could start a tsunami.
Another advance warning is if you see
the water recede so much that it exposes
areas that are usually under water. If that
happens, the only way for a person to
survive is to run for high ground, or go up
a high rise building.
Some zoologists think that animals might
be able to sense subsonic waves from an
earthquake that would cause a tsunami.
The Boxing Day Tsunami in Thailand. A mother runs
to tell her children and saves their lives.
Warnings and prevention
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Some regions use tsunami warning
systems. There are warning centers in
Hawaii and Alaska.
Honolulu has the Pacific Tsunami
Warning System. It monitors all
earthquake activity in the Pacific and
gives a tsunami warning if needed. All the
countries that border the Pacific Ocean
use the System.
Most of them also practice evacuation
and other procedures to prepare people
for tsunami. In Japan, it’s mandatory.
A tsunami warning system is now being
installed in the Indian Ocean because of
the Boxing Day Tsunami.
Pacific Tsunami Warning Center in Hawaii
Prevention
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There are other systems being developed
and used to reduce the damage from
tsunami. Buoys are used with bottom
pressure sensors to constantly monitor
the pressure of the water.
Prevention
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In some countries, they use barriers to
reduce the damage caused. Japan has
started to build tsunami walls of up to
13.5 ft. high. Other places have built
floodgates and channels to redirect the
water. However, the tsunami often surge
higher than the barriers.
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The effects of a tsunami can also be
reduced when there are trees on the
shore. Environmentalists have suggested
planting trees along the seacoast in areas
with tsunami risks. They would take years
to grow, but it would be cheaper and last
longer than artificial barriers.
Tsunami wall at Tsu, Japan
Tsunami Guidelines
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Here is some advice on what you should
do if you’re in an area that has tsunamis:
 If there has been an earthquake and
you are near the coast, listen to the
radio to learn if there’s a tsunami
warning.
 Get away from the coast, to higher
ground immediately and stay there.
 Stay away from the beach. Never go
down to the beach to watch a
tsunami come in. If you can see the
wave you are too close to escape it.
 If you see the water pull back too
much, this is nature’s warning. You
should get away immediately.
Patong Beach in Thailand.
What I have learned
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Tsunami are awesome, but can be deadly and cause a lot of destruction.
They are started by a disturbance, usually earthquakes near a body of water.
They cannot be totally prevented or predicted, so you have to look for warning signs.
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If you see the ocean pull back too much, run to higher ground.
If there has been an earthquake near the water, listen to the radio.
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Most tsunamis happen in the Pacific Ocean, usually in Japan and Hawaii.
There are Tsunami Warning Centers and evacuation routes to help.
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Sources:
– http://www.fema.gov/kids/tsunami.htm
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http://www.fema.gov/hazard/tsunami/index.shtm
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http://en.wikipedia.org/wiki/Tsunami