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Thread: What is known about the Cascadia Fault line

  1. #1
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    Default What is known about the Cascadia Fault line

    A society predicated on the assumption that everyone in it should want to get rich is not well situated to become either ethical or imaginative.

    Photographer of sailing and sailboats
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    Default Re: What is known about the Cascadia Fault line

    Really scary.
    Counting from the earthquake of 1700, we are now three hundred and fifteen years into a two-hundred-and-forty-three-year cycle.

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    Default Re: What is known about the Cascadia Fault line

    Keep reading. It gets scarier by the sentence.
    A society predicated on the assumption that everyone in it should want to get rich is not well situated to become either ethical or imaginative.

    Photographer of sailing and sailboats
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    Default Re: What is known about the Cascadia Fault line

    Whew a lot of hand jive I got lost.
    I was in San Fran for The 1989 earthquake in Loma Prieta, California, which killed sixty-three people and caused six billion dollars’ worth of damage, lasted about fifteen seconds and had a magnitude of 6.9.

    I was in a rental car felt like a flat tire then no power for 3 days. I've lived through major NY blackout, Blizzards, 9/11, Hurricane Sandy and on and on and on. I'll take 15 sec of shake rattle and roll and 77 deg & sunny 365 days a year ANYDAY
    This post is temporary and my disappear at the discretion of the managment

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    Default Re: What is known about the Cascadia Fault line

    The truth shall make ye fret.


    Good article. Really good. I recommend it. It was wrong about the collapsing houses, most timber frame houses are safe to be in during a big earthquake though there can be some pretty freaky side-effects of timber flexibility but they rarely collapse. Brick chimneys OTOH...

    Anyway, I liked this word "seafloorese", cute.
    We don't know how lucky we are....

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    Default Re: What is known about the Cascadia Fault line

    This is a pretty cool simulation of a tsunami hitting the coast.

    http://www.pac.dfo-mpo.gc.ca/science...aible-eng.htm#
    I'll just take my chances with those salt water joys.

    AR

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    Default Re: What is known about the Cascadia Fault line

    I imagine that nothing much is being done because nothing much can. And as the article said we are a short term species individually and heads in the sand rules when there is no solution. Along with climate cycles and change for whatever reason it's not sexy enough, or to scary to contemplate reality.

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    Default Re: What is known about the Cascadia Fault line

    There is more:
    July Geology Image of the Month: Ghost Forest Near the Mouth of the Copalis River, Grays Harbor County

    Posted on July 3, 2013
    The ghostly tree trunks of once-submerged red cedars pictured in the July Image of the Month have played a key role in helping geologists reconstruct the events of the last Cascadia Subduction Zone (CSZ) magnitude 9 earthquake. As DGER chief hazards geologist, Tim Walsh, recently explained to a National Geographic television crew (see image below), the combined use of radiocarbon dating and tree ring analysis on these tree trunks allowed dendrochronologist David Yamaguchi (University of Washington) and geologist Brian Atwater (U.S. Geological Survey) to date an episode of sudden coastal subsidence that drowned the trees in seawater and killed them approximately 300 years ago (sometime between August 1699 and May 1700). This time frame also coincides with numerous accounts of a tsunami of unknown origin that reached Japanese shores on January 26, 1700. In The Orphan Tsunami of 1700 Atwater, Yamaguchi and their coauthors were able to correlate that tsunami with a CSZ megathrust earthquake that triggered the land subsidence and inundation event that submerged coastal forests in the Pacific Northwest. In relating the orphan tsunami to the subsidence event at the Copalis River pictured here, Kenji Satake (Geological Survey of Japan), Kelin Wang (Geological Survey of Canada), and Atwater reviewed the size, character and timing of tsunami waves along the Japanese coast and inferred that the wave train matched what would have been expected from a magnitude 9 Cascadia Subduction Zone earthquake. Their results were published in a Journal of Geophysical Research article in 2003.
    In corroboration with the CSZ earthquake and tsunami theory, multiple records kept by Native American peoples of the Pacific Northwest also suggested violent shaking and flooding occurrences around that time. Ruth Ludwin (University of Washington) and others documented evidence found in Native Stories in a 2005 paper.
    DNR Geologist Tim Walsh explains the radiocarbon dating and dendrochronology techniques that led researchers to conclude that the trees were killed by subsidence into seawater following a CSZ M9 earthquake in 1700. Image courtesy of Michael Polenz.

    The earthquake of 1700 is the type of Cascadia megathrust earthquake we expect to reoccur in the Pacific Northwest at any time. It rivaled the magnitude and character of the Tohoku earthquake that devastated northern Japan on March 11, 2011. To Michael Polenz, the geologist who took these photographs, “it all adds up to a remarkable piece of geologic detective work, wherein coastal stratigraphic geology field work was combined with dendrochronology, ocean wave modeling, and historical research of municipal records on another continent to reveal the story of massive earthquakes here in Washington.”

    It really is quite difficult to build an ugly wooden boat.

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    Default Re: What is known about the Cascadia Fault line

    I like to think that I'm safe in Alabama but there's the New Madrid fault to worry about. There's plenty of evidence around here of the effects of the 1811 and 1812 temblers.

    https://en.wikipedia.org/wiki/New_Madrid_Seismic_Zone
    Will

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    Default Re: What is known about the Cascadia Fault line

    A Tsunami will mostly impact the pacific coast, although there will certainly be some effects in the Straits of Juan de Fuca and as far east as Whidbey Island and the San Juans in Washington as well as lesser impacts farther south in Puget Sound. In Oregon the major impact of a tsunami will also be along the coast and up the Columbia river. I would not want to be any of the major cities for a really big earthquake or on one of the sand/clay bluffs along much of the Puget Sound shoreline. On the other hand, small towns inland by more than a few miles will see much less damage.

    A 9.0 magnitude quake will certainly be catastrophic, but the impact will depend critically on where the epicenter of the quake is located. If it is offshore, the tsunami damage would be very bad while quake damage to major cities would be much less. If the epicenter in on the continent, then the risk of a significant tsunami would be greatly reduced, but quake damage would be many times worse than for an offshore epicenter.

    A Tsunami would devastate the Pacific Coast, but the absolute number of people living out there is small, so loss of life wouldn't be that huge, particularly in Oregon where much of the coast is made up of cliffs that a tsunami would not overtop. That said I wouldn't want to be vacationing in any of the small towns on the various inlets on the Oregon Coast. Seattle would feel some impact of a tsunami, but since Seattle is actually quite hilly, damage would be very localized. Earthquake damage would be much worse.

    Just my thoughts. The risk would not keep me from living out there, although it would impact where I chose to live.

    Todd Dunn
    Ph.D. Earth Sciences and retired Earth Sciences professor.

    Having grown up in the PNW all I can say is you pay your money and you take your chances. Personally, I wouldn't worry all that much since the chance of a major quake during my remaining lifetime isn't really all that great.

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    Default Re: What is known about the Cascadia Fault line



    Note that this song is from 1969.
    Last edited by ron ll; 07-13-2015 at 04:40 PM.

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    Default Re: What is known about the Cascadia Fault line

    What this article doesn't mention, but was covered in a National Geographic article a few years back, is that a good-sized jiggle (it doesn't even have to be a magnitude 9) will likely mobilize the glaciers on Mt Rainier, which are somewhat porous and unstable due to steam activity below. Once the glacier starts to move, the energy of movement will melt ice on the bottom of the glacier, reducing friction and making it move faster. The upshot is that 30 minutes to an hour after a sizable earthquake, a 40- foot wall of mud will come roaring down the side of the mountain, filling the valleys that include Puyallup, Tacoma, Auburn, Kent, Tukwila, and, ultimately, Seattle, as it makes its way to the water by way of the Duwamish River, or what's left of it. How do we know this? It's happened before. This valley had some of the most fertile farmland in the country (volcanic soils!) and plenty of water (glacial runoff!) and we paved it and put industrial parks and houses on it. We are STILL putting industrial parks, and especially houses, on it. Oh yeah--Interstate 5, the major north-south route on the west coast-- runs through this valley. Dan Huisjen refers to this scenario as Mt Rainier's "Rural Renewal Program."

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    Default Re: What is known about the Cascadia Fault line

    There's been a book written on it with all there is to know about it. Good read if the subject interests you:

    There is no rational, logical, or physical description of how free will could exist. It therefore makes no sense to praise or condemn anyone on the grounds they are a free willed self that made one choice but could have chosen something else. There is no evidence that such a situation is possible in our Universe. Demonstrate otherwise and I will be thrilled.

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    Default Re: What is known about the Cascadia Fault line


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    Default Re: What is known about the Cascadia Fault line

    As we used to say when the fear mongers warned us about "The Bomb", the best thing to do is to put your head between your knees and kiss your butt goodbye.

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    Default Re: What is known about the Cascadia Fault line

    The projected death toll of almost 13,000 seems a bit optimistic. But, as was shown by the Alaska earthquake of 1964, tsunami damage is quite variable, depending on its origin and direction. Some parts of the B.C. coast were devastated by the Alaska quake's tsunami, but others received no damage at all.

    Tom

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    Default Re: What is known about the Cascadia Fault line

    The Copalis ghost forest.


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    Default Re: What is known about the Cascadia Fault line

    Read somewhere that the pipelines that carry fuel to Portland are suspended beneath the I-5 bridge across the Columbia.

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    Default Re: What is known about the Cascadia Fault line

    I experienced the 6.8 that occurred in Feb 2001, I was in Seattle at the time. I can't imagine a 9. There wouldent be much that wasn't damaged to a sugnifigant point, even most stick frame buildings (most houses) will probably be shaken off their foundations. While building code has vastly improved over the past 50 years, much of the west coast construction is greater than 30 years old. I can't imagin a newer house withstanding a 9 without being compleat losses.

    I'll never forget the concrete slab feeling like water as I cowered under my door desk while working for Amazon.
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    Default Re: What is known about the Cascadia Fault line

    Man proposes but it's the planet that disposes.
    I do not believe that when the really big decisions are called on man is capable of making them. Caution would say that the whole population of the area, industries, services et al should move especially seeing the quake is well overdue. That won't happen.

  21. #21
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    Default Re: What is known about the Cascadia Fault line

    It is awesome to contemplate. In the original, true sense of the word.

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    Default Re: What is known about the Cascadia Fault line

    I too was here for the 6.8 in 2001, at Pierce College in Puyallup, which is all new construction. The most vivid part of my memory is watching the very earth ripple toward me as if it was a wave. It wasn't moving all that much, but it was easy to see in a wooded area as the trees tilted. The big windows on the library were flexing in interesting ways too. At home, much closer to the epicenter, no damage. A few bottles of shampoo fell off the shower wall. Dan was sitting in a truck in downtown Tacoma watching the overhead wires swing.

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    Default Re: What is known about the Cascadia Fault line

    Quote Originally Posted by McMike View Post
    I experienced the 6.8 that occurred in Feb 2001,...

    I'll never forget the concrete slab feeling like water as I cowered under my door desk while working for Amazon.
    Were you in the old hospital building on the side of Beacon Hill?

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    Default Re: What is known about the Cascadia Fault line

    In Missouri we have the New Madrid Seismic Zone. Small quakes are pretty common, but the fault hasn't cut loose with a big one since 1811 and 1812, but it has the potential to affect Missouri, Alabama, Illinois, Indiana, Arkansas, Kentucky Tennessee and Mississippi.


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    Default Re: What is known about the Cascadia Fault line

    Quote Originally Posted by L.W. Baxter View Post
    It is awesome to contemplate. In the original, true sense of the word.
    Ayup

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    Default Re: What is known about the Cascadia Fault line

    I live in a house that is about 30' from the top edge of a 300' vertical cliff above the bay. I figure when the big one hits I probably won't have a lot of time to contemplate it's awesomeness.

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    Default Re: What is known about the Cascadia Fault line

    Might be time to take up base jumping…………...

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    Default Re: What is known about the Cascadia Fault line

    Quote Originally Posted by ron ll View Post
    I live in a house that is about 30' from the top edge of a 300' vertical cliff above the bay. I figure when the big one hits I probably won't have a lot of time to contemplate it's awesomeness.
    My daughter lives just north of you on that same ridge. The house in front of hers lost half its yard a few years back due to normal slippage, normal anyway for that area. A big jolt will likely send most of that hillside down to the beach. She knows the danger, but like many, the fabulous view justifies the risk.

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    Default Re: What is known about the Cascadia Fault line

    Quote Originally Posted by skuthorp View Post
    Might be time to take up base jumping…………...
    A few years ago I used to repel down and come back up using prusik slings. Had my own private park down there as no one could get to it from the bottom.

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    Default Re: What is known about the Cascadia Fault line

    Rappel
    A society predicated on the assumption that everyone in it should want to get rich is not well situated to become either ethical or imaginative.

    Photographer of sailing and sailboats
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    Default Re: What is known about the Cascadia Fault line

    Quote Originally Posted by elf View Post
    Rappel
    If you're a 16th level Mind-Ninja it's repel...amazing technique.
    We don't know how lucky we are....

  32. #32
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    Default Re: What is known about the Cascadia Fault line

    I took the extra P when I got to the bottom.

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    Default Re: What is known about the Cascadia Fault line

    I live 30 miles north of Seattle in a 1908 home whose foundation is simply posts. Trust me, the thought of a big earthquake has been a goad in getting my boat built so I can buy a sturdier home. All I need is about another year.
    Gerard>
    Everett, WA

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    Default Re: What is known about the Cascadia Fault line

    Quote Originally Posted by ron ll View Post
    Were you in the old hospital building on the side of Beacon Hill?
    Nope, a small commercial building that they put us accounting misfits.
    "Please be more specific or we'll choose to order a cheaper bilge-rat to replace you."

    ~seanz

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    Default Re: What is known about the Cascadia Fault line

    Quote Originally Posted by KMacDonald View Post
    Here come the liberal fear mongers. Just what they needed, another something to blame on Bush.
    Oh hi, KMac. You still happening here?

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