All-Hazard Alert Broadcast (AHAB) Siren

 

What is an AHAB Siren?

Washington State Emergency Management Division developed a pole-mounted siren system that is deployed throughout the coast and inland water ways. AHAB stands for All-Hazard Alert Broadcast. This system includes several features, including:AHAB1

  • Satellite activation from the 24/7 State Emergency Operations Center.
  • Radio activation by local Emergency Management Agency.
  • Modular speaker with 360-degree coverage.
  • Ability to provide voice and tone alerts.
  • Digital voice messages may be played or the siren may be used as a public address system.
  • An intense blue light for the hearing impaired, which can also cut through fog and is visible from a long distance.

 

What does an AHAB Siren sound like?

During a routine TEST of the system, the siren will play the Westminster Chimes. The voice message below will follow the test chimes:

Voice Test Message: "The following is a test of the siren system. It is only a test. This is a test of the siren warning system. If this had been a real emergency you should tune in to your local radio station or listen to this system for further instructions. This was only a test."

Click to play:

Test Chimes

(May take a moment to download)

Upon the issuance of a TSUNAMI WARNING, the siren will play a wail sound and a voice message will follow the siren. The following voice message will be used:

Voice Warning Message: "This is NOT a Test. A tsunami warning has been issued for the coastal areas of Washington. A tsunami can cause dangerous flooding. If you are in a low coastal area, you are at risk and must move to higher ground or inland now. Do not return until directed to do so. Tune into your local radio station for additional information. This is NOT a test a tsunami warning has been issued for the coastal areas of Washington move to higher ground or inland now." (Wail)

Click to play:

Warning Siren


(May take a moment to download)

 

How do I know when to evacuate?

If you feel the ground shake, evacuate inland or to high ground immediately! A wave as high as 20 feet could reach many coastal areas within 30 minutes of the quake.

If you notice a sudden drop or rise in sea level, move to high ground or inland immediately.weather radio

If you are inside and hear a broadcast or NOAA Weather Radio alert; or if you are outside and hear an AHAB siren follow the instructions provided.

Remember - the first wave is often not the largest; successive waves may be spaced many minutes apart and continue to arrive for several hours. Return only after emergency officials say it is safe.

 For more information see: Tsunami Evacuation Tips.

 

Tsunami Alert Hierarchy:


Tsunami Warning
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A tsunami warning is issued when a potential tsunami with significant widespread inundation is imminent or expected. Warnings alert the public that widespread, dangerous coastal flooding accompanied by powerful currents is possible and may continue for several hours after arrival of the initial wave. Warnings also alert emergency management officials to take action for the entire tsunami hazard zone. Appropriate actions to betaken by local officials may include the evacuation of low-lying coastal areas and the repositioning of ships to deep waters when there is time to safely do so. Warnings may be updated, adjusted geographically, downgraded, or canceled. To provide the earliest possible alert, initial warnings are normally based only on seismic information.

Tsunami Advisory -

A tsunami advisory is issued due to the threat of a potential tsunami that may produce strong currents or waves dangerous to those in or near the water. Coastal regions historically prone to damage due to strong currents induced by tsunamis are at the greatest risk. The threat may continue for several hours after the arrival of the initial wave, but significant widespread inundation is not expected for areas under an advisory. Appropriate actions to be taken by local officials may include closing beaches, evacuating harbors and marinas, and the repositioning of ships to deep waters when there is time to safely do so. Advisories are normally updated to continue the advisory, expand/contract affected areas, upgrade to a warning, or cancel the advisory.

AHAB2Tsunami Watch -

A tsunami watch is issued to alert emergency management officials and the public of an event that may later impact the watch area. The watch area may be upgraded to a warning or advisory — or canceled — based on updated information and analysis. Therefore, emergency management officials and the public should prepare to take action. Watches are normally issued based on seismic information without confirmation that a destructive tsunami is underway.

Tsunami Information Statement -

A tsunami information statement is issued to inform emergency management officials and the public that an earthquake has occurred, or that a tsunami warning, watch or advisory has been issued for another section of the ocean. In most cases, information statements are issued to indicate there is no threat of a destructive tsunami and to prevent unnecessary evacuations as the earthquake may have been felt in coastal areas. An information statement may, in appropriate situations, caution about the possibility of destructive local tsunamis. Information statements may be re-issued with additional information, though normally these messages are not updated. However, a watch, advisory or warning may be issued for the area, if necessary, after analysis and/or updated information becomes available.

 

How are the AHAB Sirens Activated?

Washington State is a member of the National Tsunami Hazard Mitigation Program (NTHMP). The program works to ensure tsunami warning information is as accurate as possible using real-time data through deep ocean tsunami detection devices. Real-time data provides the West Coast/Alaska Warning Center with quick and reliable information to determine whether an earthquake has generated a tsunami.

Dart 2

If the event is tsunami, the tsunami detectors send data via satellite to the Tsunami Warning Centers. In turn, a message is generated via the NOAA Weather Wire Service to the National Weather Service offices and State Emergency Operations Center. A message is then sent by Emergency Alert System to NOAA Weather Radios that are located in businesses, homes, TV, and Radios. The message is also sent via satellite to the AHAB sirens on beach heads or high traffic areas to warn of a pending tsunami. Through this cycle, dissemination of a warning can be obtained rapidly and effectively.

cycle2
Tsunami Warning/Evacuation Communications Cycle

 


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