A tsunami is a series of high-energy waves radiating outward from a disturbance. Earthquakes may produce displacements of the sea floor that can set the overlying column of water into motion, initiating a tsunami. A tsunami can also be generated by a large landslide or from an underwater volcanic eruption. While many may think that a tsunami is a single large wave, it is often times several waves. These waves can sometimes be hours apart, but still caused by the same event.
Types of Tsunamis
There are two types of tsunamis, they are:
- Local Tsunami: A local tsunami provides minimal warning time for individuals to move to higher ground and evacuate. A tsunami generated from a significant Cascadia Subduction Zone earthquake would be considered a local tsunami for communities along the coastline and within parts of the Puget Sound.
- Distant Tsunami: A distant Tsunami is caused by an event far away. These tsunamis may travel for hours across the ocean. The 2011 Tōhoku earthquake and tsunami would be a distant tsunami to the United States. This tsunami traveled across the Pacific Ocean and was detected in Alaska and Hawaii.
Tsunami Inundation Maps
In the event of a tsunami predicted to affect Island County, a Tsunami warning will be issued through the Emergency Alert System (EAS). The EAS is the nation’s public warning system and will be broadcast through cable television, radio stations, and mobile devices such as cell phones.
In the event of a tsunami warning:
- Get away from the shoreline, move to higher ground and move as far inland as possible.
- Evacuate as soon as you suspect or notice signs of an impending tsunami (draining of shoreline waters that are not tide related).
- If you are in a boat, head out to sea.
What Does an AHAB Siren Sound Like?
Monthly Tests: AHAB Sirens are tested at noon on the first Monday of each month. During a routine test of the system, the siren will play the Westminster Chimes and a voice message will follow stating the following:
"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."
Actual Emergency: 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 broadcast:
“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.”