Tsunami

Tsunami. . Seaside , Devastating waves called “tsunamis” can strike Oregon’s coast at any time. These giant waves are caused by great undersea earthquakes. Such earthquakes can occur along the Cascadia Subduction Zone, one of the largest active faults in North America. This fault zone lies 32 to 70 miles offshore and roughly parallels the coast. , Tsunamis are dangerous and destructive. Cascadia tsunamis have struck the Oregon coast several times in the past 2,000 years. Most recently, about A.D. 1700, a tsunami caused by an earthquake on the Cascadia Subduction Zone flooded beaches, tidal channels, and marshes up to one mile inland from Seaside's present-day boardwalk. This tsunami and earlier ones are known to have affected large areas because tsunami-deposited sand has been found here in Seaside and in other coastal lowlands in Oregon, Washington, British Columbia, and northernmost California. , WHAT TO DO , If there is an earthquake on the Cascade Subduction Zone, Seaside could be hit by a tsunami within minutes of the ground shaking. To escape a tsunami, you must respond immediately after feeling an earthquake -- go to high ground away from the beaches, tidal channels, and other coastal lowlands. , Remember, most tsunamis are not solitary giant waves; instead many large waves may strike shore over the course of several hours. Do not return to the beach after the first tsunami wave. Wait for official word from authorities. For additional information contact your local emergency planning office or the Oregon Department of Geology and Mineral Industries.