Tsunami video offers insight to West Coast residents

A dramatic video that shows Japan’s March 12 tsunami from ground level has received a lot of attention on YouTube, probably because of its shock value. Our hearts go out to the Japanese people. Meanwhile, I believe this video can offer important insights for those of us who live or visit ocean communities on the West Coast, such as Ocean Shores.

How much time would we have to get to higher ground after an earthquake? The video shows the water level rising rapidly, as the photographer goes up a stairway to get to higher ground. At the end of the video, six minutes in, the serenity of the street has been turned into chaos.

While I worry about coastal communities, where a tsunami is a likely threat, I’m also concerned about waterfront residents and visitors along the Puget Sound shoreline. Although the chance of a tsunami in Puget Sound may be less than on the coast, one could be triggered by an earthquake on the numerous faults that run through the sound, including the Seattle, Tacoma and South Whidbey faults. Earthquakes also may cause massive landslides that can create big waves when hitting the water.

I don’t want people to be alarmed, but it would be wise for waterfront residents and frequent visitors to low-lying parks to assess how you would respond in an earthquake. Maybe you’ll decide that the risk is not worth your concern. After all, the last huge earthquake on the Seattle fault — the one that rearranged the geography of Central Puget Sound — was 1,100 years ago. Maybe you’ll decide to go to higher ground every time the shaking stops, knowing that it will be the rare earthquake that will bring a tsunami to your location.

Some places are riskier than others. If we do have a tsunami in Puget Sound, its greatest effects may occur at the dead end of estuaries, such as Silverdale on Dyes Inlet, Gorst on Sinclair Inlet and Poulsbo on Liberty Bay.

While residents on the coast have been trained to seek higher ground after they feel an earthquake and to listen for tsunami warnings, experts haven’t said much about risks in Puget Sound. For one thing, nobody can predict the chance of a massive earthquake occurring in Puget Sound. Also, the waves would come so rapidly that warnings would probably be too late. And teaching people to rush to higher ground following an earthquake could create other problems in populated areas.

Still, as you review the video above, I urge you to think of your own circumstances and plan your response. Everyone is different, but knowledge is the first step. To gain some insight into the tsunami risk, please read my story in the Kitsap Sun on Oct, 5, 2001, and the recent Water Ways entry from March 13. A video at the bottom of this page provides basic information about tsunamis. Also, you may wish to check out these reports:

Puget Sound Tsunami Sources 2002 Workshop: Geospatial Data

Reducing Earthquake-Tsunami Hazards in Pacific Northwest Ports and Harbors: Sinclair Inlet and Harbor Community Hazards, Vulnernabilities and Mitigation Actions

Puget Sound Tsunami Inundation Modeling: Preliminary Report, Phase 2

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