You may have seen pictures of the devastation brought by the tsunami (tsoo-NAH-mee) that hit Indonesia, Sri Lanka, Thailand and other countries on Dec. 26. It was one of the largest and most destructive in history.
Tsunamis can occur in any ocean, but most take place in the big body of water just off our shore -- the Pacific Ocean. They can happen day or night, any time of the year. Earthquakes that take place on the ocean floor are the most common cause. Underwater landslides and volcanoes can cause them too.
The U.S. government set up the National Tsunami Hazard Mitigation Program in 1997. This program works to improve tsunami warning systems to help protect the western U.S. coastline.
Ocean buoys have been set up that can measure tsunamis as they pass. These buoys are called Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys. The DART buoys are as big as cars. They float on the surface of the ocean and are connected to pressure recorders on the ocean floor.
A tsunami will push more water on top of the recorder. The recorder will detect this pressure. The pressure recorders send this information to the buoys. Satellites or radios then send the information to warning centers.
Computers are also used to create inundation maps of coastlines in California, Oregon, Washington, Alaska and Hawaii. These maps help scientists figure out where flooding could be the worst. The maps also help scientists plan evacuation routes. These routes help people move away from dangerous areas.
Sometimes tsunamis begin so close to shore, there is no time for an official warning. If you live along the coast, you should immediately move inland after feeling an earthquake.
You should also recognize a tsunami's warning signs. If you see the ocean suddenly withdraw from the shore or hear a loud roar, move quickly inland. Never wait to see the wave. People who can see the wave are usually too close to escape.
Sometimes there is no time to move to higher ground. In this case, you should go to the closest high-rise building that is made of reinforced concrete and head for the top floor.
Tsunamis usually are made up of many waves. The first wave may not be the largest. Do not return home until an official notice tells you it is safe.
People cannot stop tsunamis, but chances of survival are greater if you know their warning signs and obey safety instructions.
*
Samantha Bonar is the author of "Tsunamis," published by Capstone Press.
