Understanding Tsunami Alerts

Tsunami messages are issued by the tsunami warning centers to notify emergency managers and other local officials, the public and other partners about the potential for a tsunami following a possible tsunami-generating event. For U.S. and Canadian coastlines, these messages include alerts. There are four levels of tsunami alerts: warning, advisory, watch and information statement:

• Tsunami Warning: Take Action—Danger! A tsunami that may cause widespread flooding is expected or occurring. Dangerous coastal flooding and powerful currents are possible and may continue for several hours or days after initial arrival.
  Follow instructions from local officials. Evacuation is recommended. Move to high ground or inland (away from the water).
   
• Tsunami Advisory: Take Action—A tsunami with potential for strong currents or waves dangerous to those in or very near the water is expected or occurring. There may be flooding of beach and harbor areas. Stay out of the water and away from beaches and waterways. Follow instructions from local officials.
   
• Tsunami Watch: Be Prepared—A distant earthquake has occurred. A tsunami is possible.
  Stay tuned for more information. Be prepared to take action if necessary.
   
• Tsunami Information Statement: Relax—An earthquake has occurred, but there is no threat or it was very far away and the threat has not been determined. In most cases, there is no threat of a destructive tsunami.

Note: Tsunami warnings, advisories and watches may be updated or cancelled as information becomes available. Advisories, watches and information statements may be upgraded if the threat is determined to be greater than originally thought.

Tsunami warnings are broadcast through local radio and television, marine radio, wireless emergency alerts, NOAA Weather Radio and NOAA websites (like Tsunami.gov). They may also come through outdoor sirens, local officials, text message alerts and telephone notifications.

There may not always be enough time for an official warning, so it is important that you understand natural warnings. If you are at the coast and feel a strong or long earthquake, see a sudden rise or fall of the ocean or hear a loud roar from the ocean, a tsunami may follow. This is your warning. Take action and move to a safe place. Do not wait for official instructions.