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Old 10-05-2016, 03:01 AM
1,920 posts, read 1,661,356 times
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How worried are Portlanders about a potential BIG quake coming soon?

I know Seattle is at high risk. But is the risk in Portland as high, or not quite as high as in Seattle?

Any idea on the best place to be in Portland during a quake? Are those houses on the mountainside in the NW area safer than in the flat areas? Firmer ground? Or are those mountainside houses in danger of slipping off their foundations and rolling down?
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Old 10-05-2016, 07:48 AM
Location: North Idaho
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Portland is at high risk for The Big One. Ground is like pudding, every building is going to sink out of sight.

Better not move to Oregon if you worry about earthquakes.
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Old 10-05-2016, 08:36 AM
Location: Cedar Rapids, Iowa
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Portland's earthquake will be much bigger and catastrophic than the Northridge California quake in 1993. Some of those hillside homes were involved in mudslides and people were killed.
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Old 10-05-2016, 11:55 AM
Location: Left coast
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hmmm this was a subject my ex (born in Eugene btw) was fascinated with, and as Californians, we were aware of-
mountains tend to be bedrock and so its not as dangerous as one might think (depending on how the house is perched, although the house my family lives in is in the mountains, but not perched so pretty low risk)- you can get one of those soil maps of your area to see the grades of ground/ look at your earthquake risk...
Another thing that really adds to risk (aside from being swallowed up by the earth, which, actually did not come up that often) is old unreinforced masonry= old brick, and probably (we looked at a lot of these in those old 1900 cottages) post and beam foundations (we saw that were literally balanced on old boulders, not looking secure in the best of times)...
stuff like that....
at least here, in much of Portland the houses don't literally abut each other (we used to live in an apartment in a new building with steel structural supports in the walls on a separate sunken in concrete foundation/ footprint -they sunk the steel beams deep into the ground)- the whole building was designed to sway in the advent of an earthquake... )but the issue was the 1900 Victorians on either side, whether they would fall in on us....

Not an earthquake experts, but my thoughts on risk...
I guess I just accept it as something that will eventually happen at some point...
Do Portlandians normally get earth quake insurance?
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Old 10-05-2016, 01:48 PM
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Most people I know don't really do anything other than hoping for the best. I try to educate myself and prepare as much as possible but there is only so much you can do.
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Old 10-05-2016, 02:39 PM
Location: Portland, Oregon
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The easiest preparation a homeowner can take is to anchor their ground floor framing to the foundation. The Seattle quake a few years back bounced a bunch off their foundations.

Looking back at the Seattle quake again, soils along the waterfront turned to jelly. As much as the residents of the Pearl hate the sound of a pile driver that is the only foundation that will protect the new structures siting on old silt. Boring, inserting a steel bridle and filling the hole with concrete doesn't have the same structural characteristics. That is what the developers of the John Ross did, go to one of their upper floors and drop a marble.

Some slopes will slide, not all. More will slide if they are rain soaked.
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Old 10-05-2016, 03:16 PM
Location: Shelton, WA
329 posts, read 414,059 times
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check out link below.. can even type in your address to see your risk
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Old 10-05-2016, 03:21 PM
Location: Portland Metro
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Portlanders (and really everyone in western North America from Cape Mendocino to Vancouver Island, Canada) should look at home structural improvements like Nell mentions, obtaining an earthquake rider on their homeowners insurance, and stockpiling some fresh water and food.

Tokyo was 231 miles southwest of the epicenter of the 9.0 earthquake in 2011. That could be about the distance that Portland is from the epicenter of our subduction zone earthquake if it strikes off the coast of Cape Blanco--the location that scientists say is the most active part of the subduction zone. Tokyo did not fall apart, but everyone here knows that Japan is lightyears ahead of the PNW in earthquake preparedness, particularly in architecture. And they definitely felt it in Tokyo. Of course, the epicenter could be off the coast of Tillamook, which would only be 80-100 miles from Portland.

Wood-frame houses actually perform pretty well in that they generally don't collapse, but they do slip off of the foundation. There are a lot of Victorian homes in Eureka, CA that have stood for 115+ years, and that's a highly seismically active area. However, there's never been a subduction zone rip since Eureka was founded in the 1850s, so maybe that will make them fall. Often it's the severed gas lines that start fires that end up destroying houses. Know how to turn off your gas. And water main.

A couple of weeks ago somebody posted a link to a State of Oregon website with an interactive map that provided a general idea of how "loose" or "solid" the soils are and how they would respond in an earthquake. EDIT: therese marie just reposted that site URL.

Don't expect to have power for several days to several weeks. Or phone service, including cell phones (the towers may stay standing, but once the backup power supply for the tower runs out, it won't be functional). And have a plan for how to connect with family members.

Other than that, just live your life!
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Old 10-05-2016, 03:54 PM
Location: We_tside PNW (Columbia Gorge) / CO / SA TX / Thailand
30,447 posts, read 50,679,622 times
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If even a moderate quake, Portland area will become a soggy mess (for decades).

Spent last winter in NZ, the year following the Christchurch quake have been more devastating and worn the nerves / stamina raw. Mud oozing from cracks till the cows come home... shovel out the house... soon the mud oozes back in, not 1x, not 2x, but ALWAYS.

I'm high on a hill, and will probably be part of a new mudslide dam that blocks the Columbia River at Crown Point. (temporarily)
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Old 10-05-2016, 04:04 PM
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We are in as much danger as Seattle. The hillside would be one of the last places you'd want to be. Some of it is likely to turn liquid consistency and run right off the hillside bringing homes with it.

The frequency of the big quakes are measured in hundreds of years. By some estimates we are "overdue" based on the average length of time between events, but there have been lulls between big quakes longer than this one. So while could happen any time, it may also not happen in a lifetime, or a couple of lifetimes.
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