Tsunami (say tsoo-nah-me)
A tsunami is a huge wave.
It is caused by an earthquake.
Tsunami is a Japanese word meaning 'harbour wave’.
What is a tsunami?
A tsunami is a huge, long wave that comes suddenly and often without warning.
What causes a tsunami?
When an earthquake or volcano occurs, the vibrations cause a drop in the sea bed and water floods into the gap. When the gap is full, water rushes back in the opposite direction and creates a long wave.
It is not unusual for boats to end up well inland after a tsunami. This was a Fukushima street in 2011 after a huge tsunami hit this part of Japan Image©Dreamstime
Movement of tsunami
At sea, a tsunami is only slightly higher than normal waves because the ocean is deep and absorbs the energy of the tsunami. A tsunami moves at great speed, up to 800 km per hour. As it moves nearer to the coast the water is shallower and it slows down and can become higher than 50 metres.
Destruction
By the time the wave reaches the land, it is a high wall of moving water that crashes onto the land. The volume of water and the force of its impact causes huge devastation. It then draws back into the sea again, dragging with it anything in its path.
This is some of the destruction in Sri Lanka caused by a huge tsunami that also caused devastation in 15 countries of the Pacific in 2004. ©Dreamstime
Word meaning
Tsunami used to be called 'tidal waves', but this is an inaccurate term as they are not caused by tides. The Japanese word means ‘ harbour wave’.
The town of Fukushima, Japan, after a devastating tsunami in 2011. ©Dreamstime
It’s a good idea to find information from more than one source!
Read more about tsunami
https://www.ducksters.com/science/earth_science/tsunamis.php
Watch a video that explains how a tsunami forms, grows and speeds to land
https://www.youtube.com/watch?v=zVYkVhbMCpQ