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Tsunami is a Japanese word meaning ‘Harbour
Wave’. In the past the scientific community
sometimes referred to them as ‘tidal waves’ or
‘seismic sea waves’. Tsunamis are the hydrosphere’s
most destructive force. They are giant waves that are
caused by sudden movement of the seabed during an
earthquake or volcano.
Out at sea tsunami waves are low and not very
high about the size of a normal wave. As
tsunamis move into shallow water, near the shore
they start to slow down and become higher
Tsunamis are formed from earthquakes. Earthquakes can
occur when two plates in the earth's crust collide. The
earthquake causes the seabed to move quickly and water
is displaced causing waves. The half meter waves are out
at sea. They travel at extraordinary speeds of 800km/h.
the waves, at this stage are hardly noticeable on the
surface of the ocean
The waves slow down to about 300km/h as the water becomes
shallower. The waves then become closer together and only
seconds between them. The waves become really tall as they
reach the shore and pile onto one another. They can reach
amazing heights of up to 35meters. As they hit the land they
engulf everything then suck the debris back into the ocean.
* On the 27th of August, 1883
Krakatoo a volcanic island in
Indonesia erupted producing a
tsunami 35meters high it
traveled at 550km/h
destroying coastal
communities in Java and
Sumatra and killing more than
30,000 people
About 90% of tsunamis occur in
the Pacific ocean. Tsunamis are
quiet rare in the Atlantic ocean.
The most active tsunamis are along
the coast of Peru and Chile.
Tsunamis are said to occur there
once every two years
* on the 17th of July, 1998. Three
tsunami waves hit the west east
coast of Papua New Guinea, near
the town of Aitape and wiped out
entire communities along a 30km
stretch of land. It was caused by
two under sea earthquakes,
measuring 7.0 on the Richter scale.
By the time the waves hit the shore
line they reached a height of
10meters. The communities had no
warning and no where to go. Over
2,000 people were killed many of
them children. The few villagers
who survived had lost everything
* on the 21st and 22nd of May, 1960 almost 50
earthquakes produced a series of tsunamis. Which
killed 2,500 people and caused damage in Japan,
New Zealand and Hawaii. The first three waves
killed 1,700 people in Chili. When the waves hit
Hilo, Hawaii 61 people were killed
It is very difficult to predict
tsunamis because the
earthquake that causes them
may occur underwater far
away and the shock waves
may not be felt on the land.
if you are at a beach there is a
way of telling a tsunami is
coming. You might not have
much time but when you see
the water slowly draining
away into the ocean I advise
you to run. The water being
drained away contributes to
the giant wave that’s just about
to hit
www.dnai.com/~jeaniee/ocean/waves.html
www.crystalinks.com/tsunami.html
Members.tripod.com/~TSUNAMI100/index.html
Www.fema.gov/kids/tsunami/tsunamif.shtm
Www.geophys.washington.edu/tsunami/general/physics/physics.com
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