New Zealand Tsunami Facts for Students
A tsunami (pronounced soo-nah-mee) is a series of waves that is
very long and occurs over a long period of time.
Tsunamis are often caused by earthquakes or under water
landslides. The word ‘tsunami’ is a Japanese word that means
‘harbour wave’. Written in Japanese it looks like this....
“tsu” means harbour
’nami’ means wave
A tsunami can travel great distances - 17,000 kms or more - a tsunami
can be more than 200 kms in length. It can also travel very fast, at
about 750 kms an hour in some cases. Everything about the tsunami is
big, fast and wide. Tsunamis are not normal waves and are not tidal
waves either; they are giant waves that move separately from the
tides. Tsunamis can occur at any time, day or night.
Although we call them waves they appear as a surge that is pushed inland by the
force of water travelling behind them.
How did the Indian Ocean
tsunami on Boxing Day start?
A huge earthquake happened in the ocean. Two of the earth’s plates moved and
one slipped under the other. This caused part of the sea floor to drop down and all
the water dropped as well. The movement caused a big wave to start. The wave
was so-o-o-o big that it travelled thousands of kilometres – right across the Indian
Ocean to the coast of Africa, in fact it travelled right around the world and was also
recorded in New Zealand harbours – though by the time it reached New Zealand it
was only 30 cm’s high!
There is usually more than one wave in a tsunami. Some times after the first wave has
hit, people think it is all over and head back to the beach; this is a dangerous thing to
do. More waves will keep on a coming for a few hours and it is common for the first
wave not to be the biggest.
Could a tsunami hit
New Zealand?
All low-lying coastal areas can be affected by tsunamis.
A tsunami is recorded on average in New Zealand every two years but they are
usually too small to be noticed by people. It is quite rare for large tsunamis to occur.
The threat of tsunami in New Zealand is moderate to high for most of our coastline.
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What can I do to prepare
for tsunami?
If a tsunami was heading for New Zealand, the Pacific Tsunami Warning Centre in
Hawaii would detect the changes in the earth’s plates and tidal movements.
Staff would measure these changes and judge whether they were a threat or not. If
there was a threat the emergency authorities would be notified.
You can often tell that an earthquake is happening or that a tsunami is coming
because the ground shakes under your feet, the furniture may rattle
and pictures on the wall move.
Also if you are at the beach and the sea suddenly goes out this
could mean a Tsunami is coming.
If you are near the coast and you feel a really big earthquake or
one that goes on for over one minute, see the sea go out or hear a
warning, tell your family and friends and move quickly to higher ground, or as far
inland as you can in 20 minutes (walking quickly) -this could save your life and that of
others.
Be prepared!
Being prepared for any type of emergency is important. Have a plan in your family
about what you would do if a fire, flood or a tsunami happened.
You can find information about making a family plan at www.gdc.govt.nz/civildefence (the website for the Gisborne Emergency Management Office).
Know how to call for help and talk with your parents about who you should call. In
New Zealand the emergency number is 111. You can call this number when there is
an emergency, when things are not safe.
Ask your school about their emergency plan and know what you must do if there is
something unsafe at school.
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