Edmonds tsunami warning siren gets first big test this week

Workers installed the Edmonds tsunami warning siren in June. Although it has been tested regularly, Thursday’s Great Washington Shakeout will be its first time in a coordinated statewide exercise. (Photo by Larry Vogel)

A new sound is coming to Edmonds, and you can hear it this Thursday, October 21 at 10:21 am sharp.

No, the modulated wails you’ll hear (click here to listen) aren’t a pre-Halloween arrival of Ghouls, Valkyrie, or Banshees. This is the first major test of the new tsunami warning siren installed on Edmonds waterfront this summer at the foot of Dayton Street next to Olympic Beach Park. Also known as All Hazards Alert Broadcast (AHAB) sirens, the Edmonds siren is one of 121 sirens installed or planned for our state. (See attached map for locations of other AHAB sirens in the Puget Sound area)

This map shows the location of tsunami warning sirens in the Puget Sound area.

It’s all part of the Great Washington Shakeout, an annual event that not only tests warning systems, but helps raise awareness of the potential for natural disasters in our state, especially earthquakes, and more importantly, how to be prepared. when they strike. Managed by the Washington State Military Department, Shakeout takes place every year on the third Thursday in October. This year marks the tenth anniversary of the event.

A big part of the event is spreading information, educating and educating citizens on how to prepare, what to expect in the event of an earthquake, what to do when the earth starts to shake and how to stay safe until the shaking stops. This information is summarized in the downloadable and printable Washington Shakeout Poster and in this video. Local groups, schools, churches, businesses and individuals are invited to participate by registering and asking their employees, friends and associates to practice Drop, Cover and Hold On. More information in the Great Washington Shakeout FAQ here.

But back to the tsunamis.

The purple line and blue shaded area indicate probable flooding in Edmonds in the event of a tsunami.

Despite being remote from the ocean coast and mainly sheltered by the Olympic Peninsula, the coastal areas of Puget Sound are in imminent danger of flooding in the event of a tsunami. For Edmonds, this means our waterfront beaches, parks, railroads, Harbor Square, Salish Crossing and many more are at immediate risk of being affected and inundated by a tsunami wave (see flood map above). It is important to remember that this is not the kind of flooding we get because of heavy rains overcoming storm water systems and slowly increasing. These are fast, instantaneous, one-minute dry, fast-moving, deep water events that literally knock you off the hook. It’s dangerous and it can be fatal.

While earthquakes are hard to predict and usually surprise you, tsunamis usually give you time to prepare. This is because the epicenter of the earthquake that triggers a tsunami is usually far from coastal areas and the tidal wave it generates moves from the epicenter of the earthquake through the water at a predictable rate.

The speed of a tsunami depends on the depth of the water it passes through. The deeper the water, the faster the tsunami. In the depths of the ocean, tsunamis can travel as fast as a jet plane – at over 500 mph – and can cross entire oceans in less than a day. When the waves enter shallow water near the land, they slow down to a car’s speed, around 20 or 30 mph. More information on tsunamis and their behavior can be found on the NOAA / NWS FAQ here.

This NOAA map shows the coastal areas in our section of Puget Sound that are at risk of flooding in the event of a tsunami.

Depending on your distance from the epicenter, in almost all cases you have enough time to evacuate low-lying coastal areas and make your way to the heights before the tsunami hits. This is where the tsunami warning siren comes in.

When NOAA and others who monitor earthquakes detect an event, they calculate how long it will take for the tsunami to reach land and activate emergency alerts – like Edmonds’ Tsunami Warning Siren – for sites in its path.

You could be sitting on an Edmonds beach enjoying a sunny afternoon, in the midst of Dan Brown’s latest thriller, when you hear the modulated siren followed by a message in English and Spanish to immediately evacuate towards the heights. Don’t take the time to fold your chair and blanket, go for it. Evacuation maps that include escape routes and even walking times to reach the heights have been developed for many communities in Washington that may be hardest hit by tsunamis. None have been made for Edmonds yet, but new maps are being released all the time.

So listen up this Thursday morning! Since this is an exercise and not an actual alert, the warning sound will be followed by a message in English and Spanish explaining that this is only a test.

Learn more on the Washington State Division of Emergency Management website.

– By Larry Vogel

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