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| − | The Cascadia Subduction Zone is a giant fault running off the coast |
+ | The Cascadia Subduction Zone is a giant fault running off the coast of the [[Pacific Northwest]]. |
It is where the Juan de Fuca plate slides under the North American plate. When stress builds up between the plates an earthquake goes off sometimes accompanied by tsunamis. It's one of the biggest dangers towards Seattle. [[Cascadia Earthquake|The last time it went off]] was in 1700. |
It is where the Juan de Fuca plate slides under the North American plate. When stress builds up between the plates an earthquake goes off sometimes accompanied by tsunamis. It's one of the biggest dangers towards Seattle. [[Cascadia Earthquake|The last time it went off]] was in 1700. |
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Revision as of 22:55, 18 August 2006
The Cascadia Subduction Zone is a giant fault running off the coast of the Pacific Northwest. It is where the Juan de Fuca plate slides under the North American plate. When stress builds up between the plates an earthquake goes off sometimes accompanied by tsunamis. It's one of the biggest dangers towards Seattle. The last time it went off was in 1700.
Hazard to Seattle
The Cascadia Subduction Zone is in close enough range to Seattle to cause serious damage to the city. It would be "the big one" we all anticipate. A Cascadia Subduction Zone earthquake would be around 9.0 magnitude. The shaking would be so strong that you would barely or not be able to stand in it for an eternity of about four minutes.
Brick buildings would certainly collapse. So areas like Pioneer Square would be obliterated. Even with retrofits, brick constructions will still be severely damaged. Suburban housing with wooden frames could be less damaged if anchored to their foundations.
Seattle also has alot of area built on fill. In an earthquake, fill turns to liquid and structures on it can't be supported ,so they collapse as their foundations sink into the ground. Qwest Field, Safeco Field, Harbor Island, and the industrial district are all built on landfill. These areas will be the most damaged.
Experts debate what would happen to downtown's skyscrapers. In a normal quake they are some of the safest areas, but a Cascadia quake would be much stronger. Some argue they could not handle so much shaking and collapse. Others say some should remain standing. Even if they can stand, the debris from all of their damage like glass or other building material could bury the streets along with pedestrians and automobiles .
Our favorite landmark, the Space Needle was designed to resist a 9.1 earthquake luckily. The earthquake could possibly be stronger though.
Other structures at risk include highways and bridges. Notably the Alaskan Way Viaduct which is already at plan to be replaced due to earthquake risk.
Tsunamis would not pose a risk to Seattle because Puget Sound is protected by the Olympic Penninsula.
It would still be the worst disaster Seattle has ever encountered.
The threat is not very well known. So if you are visiting or living in Seattle, be prepared and remember that you are in giant earthquake country.