Can it Happen Here’ Tsunamis a Possible Threat to West Coast

January 24, 2005

Southeast Asia’s devastating tsunami has left many wondering if the threat could hit close to home. The reality is that tsunamis, in fact, have already made their mark on the West Coast, and the threat still remains today.

According to the Federal Emergency Management Agency, the greatest risk to the United States is likely a tsunami that would likely spawn off the coast of Washington, Oregon, and northern California. The series of “pressure” waves would generate from an earthquake along the Cascadia subduction zone, giving only minutes of warning time to residents along the coast of the Pacific Northwest.

Tsunamis are created when there is sudden shift in the ocean floor, usually caused by an earthquake, but also by undersea landslides or slumps, volcanoes, or even meteor impacts. Not all earthquakes produce tsunamis.

Several tsunamis have already hit land in the United States, some resulting in death. A 7.8 magnitude earthquake near the Aleutian Islands in Alaska on April 1, 1946, claimed five lives as it destroyed a steel reinforced concrete U.S. Coast Guard lighthouse on Uminak Island. That same tsunami made landfall in Hawaii some five hours later, killing a total of 165 people along the Hilo waterfront. In the aftermath of this event, the U.S. established the Pacific Tsunami Warning Center in Ewa Beach, Hawaii.

A 9.5 magnitude earthquake off the coast of Chile on May 22, 1960, resulted in a tsunami that affected the entire Pacific Rim and killed 61 people in Hilo, Hawaii.

A 9.2 magnitude earthquake hit Anchorage, Alaska on March 28, 1964, and generated a tsunami that caused damage in southeast Alaska, Vancouver Island, Washington, California, and Hawaii. Crescent City, California saw the most destruction, where the tsunami reached 30 feet and destroyed half the waterfront district. The tsunami claimed a total of 120 lives.

The Cascadia fault line last generated an estimated 9.0 — 9.5 magnitude earthquake, followed by a tsunami on Jan. 26, 1700.

An Atlantic coast tsunami is also probable, although the size of the tsunami would likely be much smaller than one that could occur on the Pacific coast.

FEMA recommends that residents of coastal communities review local evacuation routes and safe areas, and to be prepared with emergency supplies. If residents or visitors should feel strong ground shaking or see the ocean suddenly begin to recede, they should seek higher ground immediately and wait for further instructions from local officials.

FEMA further warns that tsunami waves can continue for several hours, and subsequent sets of waves can be even more dangerous than the initial waves, as they are often higher and can contain debris generated from the first set.

Additional resources can be found at www.fema.gov. To donate to the tsunami relief effort, please visit www.insurancejournal.com/tsunami/.

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