What is Tsunamis? | Types, Definition, Structure, Function & Facts
What are Tsunamis?
Tsunamis are large, strong ocean waves that get bigger and bigger as they hit the shore. They can cause great damage by flooding inland, flooding towns and destroying homes.
What can cause a Tsunami?
Tsunamis are caused by large displacement of water. Think about when you were sitting in the bathtub and stepping into the tub. This can cause a relatively large wave. The same thing happens in the ocean when large amounts of water are suddenly displaced. Several events can cause this type of motion, including earthquakes, landslides, volcanic eruptions, glacier breaks, and even meteors.
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Most tsunamis are caused by earthquakes. An earthquake occurs when a large portion of the earth’s crust suddenly shifts. When this happens underwater, large gaps can appear on the ocean floor. As water moves to fill this void, a tsunami is born.
What happens during a Tsunami?
When water moves due to an earthquake or other event, large ripple-like waves will spread from the point where the water first moved.
These waves can travel quickly and over very long distances. Some tsunamis have been known to travel thousands of miles over the ocean and travel at speeds of up to 500 miles per hour.
When waves pass through deep parts of the ocean, their crests are usually short, only a few feet high. This makes it difficult to detect tsunamis because they are not necessarily visible in the deep ocean.
As waves approach land and shallow water, they pile up and grow. At the level of the coast, a wave trench may appear. This will cause inconvenience on the shore. Water can recede for a distance. This can be dangerous as people may be tempted to step out into the open.
When waves hit the shore, it is usually a large wall of water. Water would flood land, sometimes for some distance, with great speed and power. The height of the tsunami will depend on the topography of the coast. Some tsunamis are known to reach heights of 100 feet.
Where do Tsunamis occur?
Tsunamis can occur in any large body of water. They are more common in the Pacific Ocean, where there are many earthquakes and underwater volcanoes. Countries with long coastlines on the Pacific Ocean such as Japan, Chile and the United States are all at risk of being hit by a tsunami. However, tsunamis can happen anywhere. In 2004, a massive earthquake in the Indian Ocean caused a tsunami that killed more than 230,000 people.
Why are Tsunamis Dangerous?
Although tsunamis slow down as they approach shore, they can still travel at highway speeds of more than 50 miles per hour. A huge wall of water moving at this speed can cause significant damage. A large tsunami can move several kilometers inland and wipe out entire coastal towns.
Warnings
Many coastal areas have tsunami warning systems. If an earthquake occurs that could trigger a tsunami, people are warned to leave the area or seek higher ground.
Interesting Facts about Tsunamis
Although tsunamis are sometimes called tidal waves, they have nothing to do with ocean tides.
The sequence of waves produced by a tsunami is called a wave sequence.
The first tsunami may not be the biggest. There could be bigger and stronger waves ahead.
The word “tsunami” means “harbour wave” in Japanese.
The warning system in the Pacific is called the DART system, which stands for Deep-ocean Assessment and Reporting of Tsunamis.