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1700 Cascadia Earthquake

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Re: 1700 Cascadia Earthquake

#61

Post by noahtallen »

mxcrossb wrote: post #45
akiselev wrote: post #30

Earlier quoted context omitted.

That figure comes with a caveat that's mentioned towards the end of the article: > As for casualties: the figures I cited earlier—twenty-seven thousand injured, almost thirteen thousand dead—are based on the agency’s official planning scenario, which has the earthquake striking at 9:41 A.M. on February 6th. If, instead, it strikes in the summer, when the beaches are full, those numbers could be off by a horrifying ma…

If this is the case, it seems like you could get a lot of bang for your buck by building up a beach evacuation infrastructure.

All along the Oregon coast are signs indicating where the tsunami impact zone is, and I think there are also alarms in a lot of towns too.

Re: 1700 Cascadia Earthquake

#62

Post by jvolkman »

Exmoor wrote: post #33
thedigitalone wrote: post #5

"Our operating assumption is that everything west of Interstate 5 will be toast." Ouch.

It's a weird statement to make, because the route of I5 is fairly arbitrary, geologically speaking. Lower parts of downtown Seattle may be at risk, but is upper Queen Anne hill? Ballard may be partially screwed, but Crown Hill is hundreds of feet higher in elevation. That assumes that Puget Sound even generates a large Tsunami based on an offshore quake. If we're talking about Oregon it gets even weirder since the po…

Not sure if this is what they're referring to, but in the downtown area I-5 traces the original shoreline. Everything to the west is fill from Seattle's many regrades. https://youtu.be/oSSxdogrv1s?t=519

Re: 1700 Cascadia Earthquake

#63

Post by rconti »

I remember in early 2001, reading an article in the NYTimes or Seattle Times about the quake risk in Seattle, showing an easterly view of downtown from Puget Sound. In it, a line was drawn, showing a fault line, just about 4 blocks south of the Kingdome/Safeco Field area, along with the usual panic about how bad an earthquake could be in the region.

This article and that image flashed through my mind when not more than a few weeks later, I found myself sitting on the 4th and uppermost floor of a 100+ year old brick building, precisely where that fault line was drawn, as the floor started bouncing, then swaying, then the ceiling lamps were swinging back and forth so violently that they were hitting the ceiling on either side, and interior brick walls started to give way.

I worked in that building for another year and a half after that February 2001 6.8 magnitude Nisqually Quake[1], and every time a truck bounced down the potholes of 1st Avenue South, and the office floor bounced, my palms would sweat.

[1] https://en.wikipedia.org/wiki/2001_Nisqually_earthquake

Re: 1700 Cascadia Earthquake

#64

Post by 29athrowaway »

The strongest earthquakes in recent history (1906-2005):

1. https://en.wikipedia.org/wiki/1960_Valdivia_earthquake

2. https://en.wikipedia.org/wiki/1964_Alaska_earthquake

3. https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_a...

Those 3 amount for over 50% of all the energy released by earthquakes in that period.

https://upload.wikimedia.org/wikipedia/commons/7/79/Graph_of...

There's this one too: https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_an...

Re: 1700 Cascadia Earthquake

#65

Post by bombcar »

rconti wrote: post #63

I remember in early 2001, reading an article in the NYTimes or Seattle Times about the quake risk in Seattle, showing an easterly view of downtown from Puget Sound. In it, a line was drawn, showing a fault line, just about 4 blocks south of the Kingdome/Safeco Field area, along with the usual panic about how bad an earthquake could be in the region. This article and that image flashed through my mind when not more th…

California gets hit with earthquakes quite often, and so has been made more resilient.

When a big one hits Seattle or the Midwest is when you’ll see untold damage. Just compare bridge pillars in various parts of the country.

Re: 1700 Cascadia Earthquake

#66

Post by lwansbrough »

I live on the 8th floor of an old 60's Vancouver 18-story apartment complex. I'd like to be out of here sooner than later, as I suspect this building and many like it will simply collapse entirely when the big one hits. Similar, erm, paranoia is why I would never purchase in Richmond/Delta. Liquefaction of that entire region is possible - not something I like to think about!

Re: 1700 Cascadia Earthquake

#67

Post by Spooky23 »

ZDurmPhoto wrote: post #44

I live in Portland and have a slide-in truck camper on my property. I use it for camping of course, but it is also part of my earthquake preparation plan. It is solar powered but also has a built-in propane generator. It is fully self-contained with all the comforts of home including fresh water storage, a galley with oven, stove, freezer and fridge. A bathroom plus a hot shower, comfortable bed, large pantry, closet…

This type of stuff is what always made the west coast unappealing. Where I live, disaster is a bad ice storm, blizzard or localized flooding.

Complete devastation just isn’t my thing.

Re: 1700 Cascadia Earthquake

#68

Post by tresil »

breakyerself wrote: post #58

Here is an excellent lecture on the subject from CWU professor Nick Zenter. If you watch this there is a good chance you'll decide to watch all of his lecture on the channel. Very enthralling. https://youtu.be/UJ7Qc3bsxjI

Nick’s geology talks are a near-perfect mix of academic science, and dynamic storytelling.

Re: 1700 Cascadia Earthquake

#69

Post by shkkmo »

bombcar wrote: post #65
rconti wrote: post #63

I remember in early 2001, reading an article in the NYTimes or Seattle Times about the quake risk in Seattle, showing an easterly view of downtown from Puget Sound. In it, a line was drawn, showing a fault line, just about 4 blocks south of the Kingdome/Safeco Field area, along with the usual panic about how bad an earthquake could be in the region. This article and that image flashed through my mind when not more th…

California gets hit with earthquakes quite often, and so has been made more resilient. When a big one hits Seattle or the Midwest is when you’ll see untold damage. Just compare bridge pillars in various parts of the country.

When the "big one" hits the pacific NW, bridge design is not going to save significant areas from complete destruction.

I am talking about the Cascadian Subduction Zone letting go which happens every 200 to 1200 years (41 times in the last 10000 years). The last time this happened, in 1700, there was a 9.0 earthquake, a 100 foot tsunami and the coastline dropped several feet.

There is about a ~10% chance this will happen again in the next 50 years. If it does, large areas will be completely unprepared and a very large number of people will die.

Re: 1700 Cascadia Earthquake

#70

Post by hodgesrm »

kibwen wrote: post #12
supernova87a wrote: post #10

I love how some cultures have recordkeeping that goes back hundreds of years that can be tied to explain some unusual sediment deposits found halfway around the world.

Nearby this in Oregon is Crater Lake, which is the stunning remnant of a catastrophic volcanic eruption 7,700 years ago. The volcanic explosivity index classifies it as a 7, "super-colossal", i.e. an order of magnitude larger than Krakatoa. And indeed there are Native American tribes who have passed down the story of the eruption over the millennia, believing it to be the site of a battle between gods. Super cool to…

The impressive thing about the Crater Lake/Mount Mazama eruption is that you can still find the ash layer from it in locations hundreds or even thousands of miles away. There's an 8 inch layer visible in many locations in the Okanagan Valley of Northern Washington, which is about 500 miles away by car.

[1] https://en.wikipedia.org/wiki/Mazama_Ash

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