Tsunami/Phase 1/Lesson1 3

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Wave energy and speed


Tsunami waves have a lot of energy and travel much further than ordinary waves. Have a look at this animated model of the Chilean Tsunami (note: animation may take some time to load) to see how far the tsunami travelled from the earthquake location.

On the open ocean, tsunami waves are small and not easily noticed by aircraft or ships because they appear more like ordinary waves on the sea surface. But when the waves enter shallow water they will rise in height and move faster. Some tsunami can be very large and can rapidly and violently swamp coastlines, such as a tsunami did to the island of Upolu (the most damaged island in Western Samoa in the 2009 Samoan Tsunami), causing loss of life and property damage. Other tsunami can be small, but are still dangerous to people and property near or in the coastal water.

For example, the tsunami that was generated by the earthquake in Chile (February 27 2010) travelled at hundreds of kilometres an hour all the way to New Zealand and beyond. Strong currents are also characteristic of tsunami waves, which means that even when the height of the water in a tsunami is not great, there is a lot happening beneath the surface that makes even the smallest tsunami dangerous.

It is important to remember that not all earthquakes will generate a tsunami, and that earthquakes are not the only sign of an impending tsunami. It is also important to remember that tsunami can occur at any season of the year and at any time, day or night.


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Survival Agent

This means that as the Survival Agent for your community, you will need to be aware of the facts about tsunami. Some people might believe that a small tsunami is not dangerous, or that the only thing that can cause a tsunami is an earthquake. But both of these beliefs are false and it is important that you know the facts so that you can be prepared and help your community and others.

Take this short quiz below to check that you understand all of the facts covered so far and to make sure you are starting out well as a Survival Agent.

Multichoice Quiz


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Multichoice Quiz

 

Answer the following questions:

1. A tsunami is a series of giant waves generated by

a. High winds
Incorrect.
b. Stronger than normal tides
Incorrect.
c. Large disturbance on ocean floor
Correct.
d. Storms
Incorrect.

2. What does the word tsunami mean?

a. Big wave
Incorrect.
b. Earthquake wave
Incorrect.
c. Harbour wave
Correct.
d. Tidal wave
Incorrect.

3. What do tsunami look like in the open sea?

a. Hardly noticeable waves
Correct.
b. Small cresting waves
Incorrect.
c. Huge cresting waves
Incorrect.
d. Huge non-cresting waves
Incorrect.

4. How far apart can waves of a tsunami be?

a. There is only one wave
Incorrect.
b. Only a few seconds
Incorrect.
c. Only a few minutes
Incorrect.
d. Up to an hour
Correct.

5. Tsunami can occur

a. Only in the morning
Incorrect.
b. Only in the evening
Incorrect.
c. Any time of the day or night
Correct.
d. Only in the summer months
Incorrect.

6. Tsunami are known for being able to:

a. Violently flood coastlines
Incorrect.
b. Cause devastating property damage
Incorrect.
c. Cause injuries and loss of life
Incorrect.
d. All of the above
Correct.

7. In what year did the Boxing Day tsunami occur in the Indian Ocean?

a. 1999
Incorrect.
b. 2004
Correct.
c. 2007
Incorrect.
d. 2010
Incorrect.

8. Which of the following events do not cause tsunami?

a. Underwater or coastal earthquakes
Incorrect.
b. Large coastal cliff or lakeside landslides
Incorrect.
c. Underwater volcanic eruptions
Incorrect.
d. Plane crash into the ocean
Correct.

9. Which island in Western Samoa suffered the most damage when the tsunami struck on 29 September 2009?

a. Apia
Incorrect.
b. Upolu
Correct.
c. Savaii
Incorrect.
d. Stewart Island
Incorrect.

10. Which statement below is untrue?

a. Tsunami waves are different from ordinary waves that you see at the beach
Incorrect.
b. Tsunami waves have a lot of energy and travel much further than ordinary waves
Incorrect.
c. Small tsunami are not dangerous
Correct.
d. Not all earthquakes will generate a tsunami
Incorrect.

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