This web page broadly identifies and describes the tsunami hazards that Oregon faces. It also highlights previous plans, assessment tools, and resources that have been developed to identify, profile, and assess the vulnerability from tsunami events in Oregon. Tsunamis are caused by earthquakes under the ocean or by landslides into or under the ocean. A tsunami, often incorrectly referred to as a “tidal wave,” is a series of waves that can travel great distances from their source and inundate coastal areas. The time of arrival of tsunami waves depends on a location’s distance from the source event. For example, tsunami waves from local earthquakes may arrive between 5 and 30 minutes after the earthquake has started. Waves generated by distant sources may arrive hours after the earthquake has occurred. Tsunamis pose a real threat to Oregon coastal communities from Cascadia Subduction Zone earthquakes and also from distant earthquakes near Alaska or Asia.

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The Oregon Coast Region borders the Pacific Ocean on its western edge, and thus is the only region that would be directly affected by tsunamis. All of Oregon’s 60 cities and unincorporated communities facing the Pacific Ocean or located on Oregon’s bays and estuaries are vulnerable to damage from tsunamis to varying degrees.

Because tsunamis typically occur as a result of a seismic or volcanic event, the timing and magnitude of such events adds to the difficulty in adequately preparing for such disasters. If a major earthquake occurs along the Cascadia Subduction Zone, a tsunami could follow within 5 to 30 minutes. Although tsunami evacuation routes have been posted all along the Oregon Coast, damage to bridges and roadways from an earthquake could make evacuation quite difficult even if a tsunami warning were given. In addition, if a major earthquake and tsunami occur during the “tourist season,” causalities and fatalities from these disasters would be far greater than if the same events occurred during the winter months.

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