Tsunami

Tsunamis (pronounced soo-ná-mees), also known as seismic sea waves (mistakenly called “tidal waves”), are a series of enormous waves created by an underwater disturbance such as an earthquake, landslide, volcanic eruption, or meteorite. A tsunami can move hundreds of miles per hour in the open ocean and smash into land with waves as high as 100 feet or more.

 

From the area where the tsunami originates, waves travel outward in all directions. Once the wave approaches the shore, it builds in height. The topography of the coastline and the ocean floor will influence the size of the wave. There may be more than one wave and the succeeding one may be larger than the one before. That is why a small tsunami at one beach can be a giant wave a few miles away.

 

All tsunamis are potentially dangerous, even though they may not damage every coastline they strike. A tsunami can strike anywhere along most of the U.S. coastline. The most destructive tsunamis have occurred along the coasts of California, Oregon, Washington, Alaska, and Hawaii.

 

Learn more about tsunami preparedness here.

During a tsunami....

 

  • Listen to your radio or television for a tsunami warning or if an earthquake occurs and you are in a coastal area.
  • Move to higher ground inland and stay there.
  • Have an Emergency Supply Kit and Household Disaster Plan and take them with you.

 

Terms

Familiarize yourself with these terms to help identify a tsunami hazard:

 

  • Advisory
    An earthquake has occurred in the Pacific basin, which might generate a tsunami.
  • Watch
    A tsunami was or may have been generated, but is at least two hours travel time to the area in Watch status.
  • Warning
    A tsunami was, or may have been generated, which could cause damage; therefore, people in the warned area are strongly advised to evacuate.