01 Tsunami

Tsunamis happen when a large volume of water is displaced. This is usually caused by an earthquake, volcano, or landslide. However, they can also be caused by an underwater explosion or the impact from a meteorite. The disturbances caused by these phenomena cause extremely long waves resembling a very fast rising tide. Large tsunamis can reach heights of over 30 metres and travel at speeds up to 800 kilometres per hour! Most of them occur in the Pacific Ocean's Ring of Fire. When they happen, they can be very deadly to those who live in coastal areas.

Because of their extremely high rate of speed, Tsunamis can cross the Pacific Ocean in just one day. As they get closer to shore they gain more strength and energy. The top of at sunamiactually moves faster than the bottom. That's why they rise so high. Just before a tsunamihits shore, the coastal water is sucked away from shore, exposing the sea floor. The firs wave is usually not the strongest. The waves that follow gain strength and size.

Hawaii experiences the most tsunamis in the world, averaging about 1 a year. However, only about one every seven years causes damage.

The 2004 tsunami in the Indian Ocean killed more than 230,000 people in 14 countries. It was estimated to have the power equivalent to 23,000 atomic bombs!

Some people refer to tsunamis as tidal waves, but this is wrong because they have nothing to do with tides. If a person is hit by a tsunami, the best thing to do is grab something that floats — not try to swim.

Word List

phenomena : natural things that happen

Ring of Fire : the Pacific Coas

You Practice

I. By the numbers—What is the meaning of these numbers in the reading?

1) 30 metres_____________________________________________

2) 800 kilometres_________________________________________

3) 230,000 people________________________________________

4) 23,000 atomic bombs___________________________________

5) 14 countries___________________________________________

II. Answer the following questions.

1) What are the main causes of tsunamis?

2) What makes tsunamis so dangerous?

3) What is a clue that a tsunami is about to hit the shore?

4) Where do most tsunamis happen?

5) What would you do if you were hit by a tsunami?

III. True / False / Not Given—Write T if the sentence is true, F if the sentence is not true, or NG if there is no information about the sentence.

____ 1) Tsunamis can be caused by earthquakes.

____ 2) Japan has the most tsunamis.

____ 3) “Tidal wave” is a good name for tsunamis.

____ 4) Tsunamis move quite slowly.

____ 5) Tsunamis can happen outside the “Ring of Fire”.