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What Is A Tsunami?

August 31, 2012

By WeatherBug Meteorologist, Andrew Rosenthal

Tsunami Warnings have been issued across the western Pacific Rim, including parts of Japan and Indonesia after a 7.6 magnitude earthquake hit just off the east coast of the Philippines. What is a tsunami and what can you do to protect yourself?

A tsunami is a set of ocean waves that is caused by a large disturbance of the sea or sea floor. Often, this disturbance is caused by an earthquake, which was the case today.

Tsunamis will often occur several hours after the earthquake. The undersea waves typically move about 400 to 500 mph, similar to an airliner`s speed, away from the epicenter, with wave heights of just a few feet in the open ocean.

However, as the waves start to approach land, they will begin to slow down and grow larger above the sea surface. Then, the waves smack into the shoreline, wiping out everything in its path.

While it is impossible to predict specifically where and when a tsunami will occur, once it is generated the waves can be forecast through modeling and undersea measurements.

A Tsunami Warning is issued when a tsunami of some size is likely to occur. By contrast, a Tsunami Advisory means that the possibility exists of some tsunami waves, albeit likely smaller in size.

What can you do to protect yourself during a tsunami?

  • First, heed any official warning information, especially if you live near the coast. It is nearly impossible to predict the exact height of the wave, so be prepared to evacuate.
  • Remain calm. There is often hours between the earthquake and the subsequent waves to prepare for a tsunami`s arrival.
  • Have non-perishable food on hand, as the waves could take out electricity.
  • Drive, or walk to higher elevation if roads become swamped. This elevation should be more than 100 to 200 feet above sea level.
  • Do not go into the ocean. The wave is extremely fast-moving and you will be unable to swim against its riptide.
  • Wait for the all-clear. The tsunami can consist of several waves, with as long as 1 to 2 hours between individual waves.

Be sure to stay with WeatherBug for the latest on the tsunami threat and have your WeatherBug active for the latest weather alerts in your neighborhood. Get the latest updates anywhere on Twitter.

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