Tsunami

By Alexandra Busato

April is Tsunami Awareness Month!

Origin of the word

• Tsunami is a Japanese word. Tsu means "harbor", and nami means "wave". Tsunami are common in the history of Japan. There have been almost 200 so far in Japan that have been recorded. The Greeks were writing about it in 426 B.C.

Tsunami warning sign

on a seawall in Japan

How a tsunami is formed

• A tsunami is a series of huge waves caused by a disturbance undersea, usually earthquakes, but also landslides, volcano eruptions or meteorites.

• A tsunami can move hundreds of miles per hour in the open ocean and smash into the land with waves as high as 100 feet or more.

• Tsunamis are hard to notice while they are in the water. They have a small wave height (amplitude), and a very long wavelength. They only grow in height as they reach the shore. This is called shoaling.

What a tsunami is like

• The waves travel in all directions, like the ripples you get after throwing a rock. They can cause a lot of destruction on the shore.

• Sometimes, there is more than one wave, and the one that comes after could be larger.

• They are sometimes called "tidal waves," but tsunami have nothing to do with the tides.

Boxing Day Tsunami in Thailand, 2004

• This is a map of tsunamis that have happened in the world. There have been almost 2000 tsunamis so far. The size of circle is proportional to the magnitude. Red is for tsunamis that only happened in oceans, purple is for regional tsunamis that caused deaths, and blue is for all other tsunamis.

• About 80% of all tsunamis occur in the Pacific Ocean, but they are possible wherever there is a large body of water. Tsunami are not rare. There were at least 25 in the last century. Many were recorded in the Asia–Pacific region, especially in Japan.

• A tsunami can strike anywhere on most of the U.S. coastline. Hawaii is the state with the most tsunamis. They get about one a year.

Dangers

• All tsunamis can be dangerous. Deaths are usually caused by drowning.

• The tsunami waves and the receding water can destroy buildings in its path.

• There is also the danger of flooding, water being contaminated, and fires being started from ruptured gas lines or tanks.

Houses in Sumatra in Indonesia, flooded by the Boxing Day Tsunami of 2004.

Famous Tsunami

• In 1946, there was an earthquake in Alaska, that started a tsunami which flooded Hilo on the island of Hawaii with waves of 20 to 32 feet.

• On December 26, 2004, the Boxing Day tsunami in the Indian Ocean killed over 300,000 people, and injured many more. When the sea pulled back, many people went on the shore to investigate and most of them died.

• This photo was taken when the Boxing Day tsunami hit Thailand on December 26, 2004

Boxing Day Tsunami in Thailand, 2004.

Signs of an approaching tsunami

• A tsunami cannot be prevented or predicted, but there are warning signs. If there’s an earthquake near a body of water, it could start a tsunami.

• Another advance warning is if you see the water recede so much that it exposes areas that are usually under water. If that happens, the only way for a person to survive is to run for high ground, or go up a high rise building.

• Some zoologists think that animals might be able to sense subsonic waves from an earthquake that would cause a tsunami.

The Boxing Day Tsunami in Thailand. A mother runs to tell her children and saves their lives.

Warnings and prevention• Some regions use tsunami warning

systems. There are warning centers in Hawaii and Alaska.

• Honolulu has the Pacific Tsunami Warning System. It monitors all earthquake activity in the Pacific and gives a tsunami warning if needed. All the countries that border the Pacific Ocean use the System.

• Most of them also practice evacuation and other procedures to prepare people for tsunami. In Japan, it’s mandatory.

• A tsunami warning system is now being installed in the Indian Ocean because of the Boxing Day Tsunami. Pacific Tsunami Warning Center in Hawaii

Prevention

• There are other systems being developed and used to reduce the damage from tsunami. Buoys are used with bottom pressure sensors to constantly monitor the pressure of the water.

Prevention

• In some countries, they use barriers to reduce the damage caused. Japan has started to build tsunami walls of up to 13.5 ft. high. Other places have built floodgates and channels to redirect the water. However, the tsunami often surge higher than the barriers.

• The effects of a tsunami can also be reduced when there are trees on the shore. Environmentalists have suggested planting trees along the seacoast in areas with tsunami risks. They would take years to grow, but it would be cheaper and last longer than artificial barriers. Tsunami wall at Tsu, Japan

Tsunami Guidelines

• Here is some advice on what you should do if you’re in an area that has tsunamis: If there has been an earthquake and

you are near the coast, listen to the radio to learn if there’s a tsunami warning.

Get away from the coast, to higher ground immediately and stay there.

Stay away from the beach. Never go down to the beach to watch a tsunami come in. If you can see the wave you are too close to escape it.

If you see the water pull back too much, this is nature’s warning. You should get away immediately.

Patong Beach in Thailand.

What I have learned

• Tsunami are awesome, but can be deadly and cause a lot of destruction.

• They are started by a disturbance, usually earthquakes near a body of water.

• They cannot be totally prevented or predicted, so you have to look for warning signs. – If you see the ocean pull back too much, run to higher ground. – If there has been an earthquake near the water, listen to the radio.

• Most tsunamis happen in the Pacific Ocean, usually in Japan and Hawaii.

• There are Tsunami Warning Centers and evacuation routes to help.

• Sources:

– http://www.fema.gov/kids/tsunami.htm

– http://www.fema.gov/hazard/tsunami/index.shtm

– http://en.wikipedia.org/wiki/Tsunami