Tsunami

The Pacific Coast, Strait of Juan de Fuca, Puget Sound, and large lakes are at risk from tsunamis, which are trains of waves that threaten people and property along shorelines. Sudden raising or lowering of the earth’s crust during earthquakes generally causes a tsunami, although landslides and underwater volcanic eruptions also can generate them. Movements of the sea floor or lake bed, or rock fall into an enclosed body of water, displace the water column, setting off a series of waves that radiate outward like pond ripples.

Only as a tsunami approaches land does it become a hazard; in shallow water, it gains height as its waves slow and compress. Tsunamis do not resemble their usual icon, a towering wave with a breaking crest. Instead, they come onshore resembling a series of quickly rising tides, and they withdraw with currents much like those of a river. Swift currents commonly cause most of the damage from tsunamis. A Pacific Ocean tsunami can affect the entire Pacific basin, while a tsunami in inland waters can affect many miles of shoreline.

Tsunamis typically cause the most severe damage and casualties near their source. There, waves are highest because they have not yet lost much energy. The nearby coastal population often has little time to react before the tsunami arrives. Persons caught in the path of a tsunami often have little chance to survive; debris may crush them, or they may drown. Children and the elderly are particularly at risk, as they have less mobility, strength, and endurance.

If you live on the coast, you might be curious about the Tsunami All-Hazard Alert Broadcast (AHAB) and its pole-mounted siren system deployed throughout the coast. During a routine TEST of the system, which is conducted on the first Monday of every month at noon, the sirens will play the Westminster Chimes (click here to listen to what it sounds like). Upon the issuance of a TSUNAMI WARNING, the siren will play a wail sound (click here to listen to what it sounds like) and a voice message will follow the siren.

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Tsunami Warnings and Information

Tsunami Evacuation Maps by County (DNR)
Some brochures are tabloid-size (11 x 17 in.). The "upside down"  orientation of part of the second page is because they were designed to be folded in half and then in thirds. They can be printed on letter-size paper by telling your printer to shrink to fit or scale to 50 percent.

Understanding Tsunami Hazards in Washington - Fact Sheets by County (PDF)

Tsunami Preparedness Information

Project Safe Haven Reports

Project Safe Haven is a grassroots, community driven, public process currently taking place on the Washington Coast to identify areas for future vertical evacuation structures. Partnering with local residents, its mission is to develop a community responsive vertical evacuation strategy along the Washington coast.

Final Report Cost Breakdown

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