Puget Sound (Seattle) Area Earthquake Study

This is a link to an excerpt from:

Scenario for a Magnitude 6.7 Earthquake on the Seattle Fault

http://www.metrokc.gov/prepare/docs/EC_SeattleScenarioFinal.pdf

A study done by the Earthquake Engineering Research Institute and funded by the Washington Emergency Management Division.

This 33 page document was considered "alarmist" when first released but the scenario outlined is actually considered to be reasonable by the King County Department of Emergency Management Director, Eric Holdeman.

An interesting read and a good reason to develop some basic family plans. (I work 2 blocks from the Seattle fault).

This is from Eric Holdeman....

A team of professionals has put together an earthquake scenario that is intended to be predictive of the types of damages and injuries that will occur if a 6.7 magnitude earthquake would hit the Seattle Fault. This is not a worst case scenario! I know some people who read the final draft of "The Scenario for a Magnitude 6.7 Earthquake on the Seattle Fault" and thought it was alarmist and extreme. Let me assure you that it is not so. It does show how a shallow crustal fault running through the middle of a high-density populated urban area with a great amount of infrastructure might be impacted. While terrorism has been the "désastre de jour" from the Department of Homeland Security for the last four years, I can assure you that at some point in our future, this area of the Central Puget Sound will have an event as described in this study or much worse!.

I can't seem to open this. I get a box that says "Click the program you want to use to open." But nothing seems to work-- it's all gibberish & little squares. Any thoughts?

Sue

Use Adobe Acrobat.

If you have Acrobat already installed try saving it to the local drive then open. You might need a later version of acrobat too if it is already installed and wont open.

you can download it from www.adobe.com and follow the download Acrobat Reader links.

The word I've been hearing from the Seismologists at U of W for the past 10 years is to expect nothing less than an R 9+ earthquake in that region. Greater than 9 on the Richter scale? I don't think there's been one in recorded history has there? They said it was past due a decade ago.

Yet another good reason why I moved out of the Seattle Tacoma area. <img src="/images/graemlins/grin.gif" alt="" />

The Kamchatka earthquake in 1952, & the quake last year off the western coast of Sumatra were both 9s.

The 1960 quake in Prince William Sound (AK) in 1960 was a 9.2.

The worst one was in Chile, also in 1960, and it was a 9.5.

But these are only the ones recorded with modern equipment.

The New Madrid, MO quakes of 1811 & 1812 made a lot of changes in the terrain, but is estimated to have been "only" an 8+. They affected the topography more than any other earthquake on the North American continent, and were felt from east of the Rockies to the Atlantic seaboard. Large areas sank into the earth, new lakes were formed, the course of the Mississippi River was changed, and forests were destroyed over an area of 150,000 acres. They also caused the Mississippi River to flow backwards for a while, and rang church bells in Boston, MA.

It isn't just the magnitude that does the damage, it's the depth, the direction, and what's built on top of it, plus what else it can affect, like volcanoes & tsunamis, plus myriad other conditions.

Bob Hope once referred to an earthquake as a mountain range doing the Funky Chicken.

Sue

Well, that's bad news, since the Seattle quake is expected to be rather deep. <img src="/images/graemlins/frown.gif" alt="" />

The New Madrid earthquakes effects were so widespread due to the type and depth of the fault plus the geology of the area (i.e. East of the Rockies) See compairison image..

The really big one expected to hit the U. S. and Canadian Northwest will come from the Cascadia Subduction Zone. It is expected to have effects much like the December 2004 Indonisia earthquake.

Now, where did I leave my hardhat? <img src="/images/graemlins/shocked.gif" alt="" />

Stay safe.

JimJr

According to the Geographic Survey of Canada, a Canadian government department, the chance of a large subduction earthquake occuring in the NorthWest, is one in every 300 to 500 years. The last known one occured January 26, 1700, so we have a next event window of about 200 years. Earthquake prediction is not an exact science by any stretch of the imagination. Nobody really knows when the next big one will happen, all we know is that eventually, it will happen.

Some thoughts:

Given that a 1' snowfall can shut down all the roads in the area, imagine what might happen if there was debris on the roads?

The ferry system would be useful in evacuations, IF the ferries and dock systems were still intact.

Expect that downtown would become impassable -- steep roads, old buildings and some of the streets are hollow.
( Take the underground tour)

tro