US is long over due for large quake

WASHINGTON – The western United States is overdue for a huge earthquake and tsunami much like the one that devastated Japan last week, and is nowhere near ready to cope with the disaster, experts say.

A volatile, horseshoe-shaped area known as the Pacific Ring of Fire has recently erupted with quakes in Chile, Japan, Mexico and New Zealand, and seismologists say it is just a matter of time before the next big one hits.

"From the geological standpoint, this earthquake occurs very regularly," said geotechnical engineer Yumei Wang, who is the geohazards team leader at the Oregon Department of Geology.

"With the Cascadia fault, we have records of 41 earthquakes in the last 10,000 years with an average of 240 years apart. Our last one was 311 years ago so we are overdue," she said.

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Just like Yellowstone which is way overdue to go off big time, so are we due for the big one on the west coast. You can't predict earthquakes with any degree of definitive accuracy. No matter what people claim. At least not close enough to convince me you can. However, you can predict and see trends in activity as well as damage patterns from such quakes.

The Japanese are way better prepared for earthquakes than we are, especially in Oregon and Washington, and we all have seen in the last few days what still happened there. What will happen when this hits us?

For an example of what might happen, or probably will happen we look here:

If 'The Big One' hits, Madin said, "Buildings and bridges would sway back and forth, back and forth, and its hard for structures to tolerate repeated shaking for a long period of time. Most of the earthquakes in California last 20 seconds or 30 seconds, but we are talking about two plus minutes of shaking." The reason for the longer shaking: the Cascadia is 600 miles long, and it will take that to make its way from the bottom of the fault line to the top. Madin said, "We pretty much have to plan on Portland being two cities after this hits." He said our bridges would not be able to survive that much shaking.

Structural engineer, Kent Yu, specializes in earthquake structures at Portland based Degenkolb Engineers. He said, "We are living on borrowed time." Yu said all of Portland's bridges would likely collapse. He said 60 percent of buildings in downtown Portland would not be left standing, because they are not designed for earthquakes.

This fault line was not even known to exist until the 1980's. The strain accumulation on this subduction zone has a big history of relieving it's strain all at once in large quakes. The earthquake department of Berkley University has released a report of the strain they have found in this area. Their report basically shows that:

The observed horizontal strain rates indicate that strain is accumulating everywhere along the CSZ from Cape Mendocino to the Strait of Juan de Fuca. These observations do not indicate whether the strain will ultimately be released by a single great M$\sim $9 earthquake, by a sequence of smaller M$\sim $8 earthquakes, or by some other scenario. However, we find no evidence that the megathrust is segmented by shallow regions where strain is not accumulating, so the hypothesis that the strain could be released by a single great earthquake cannot be rejected. Measurements by recent GPS surveys and permanent GPS stations installed since 1996 [e.g.,Khazaradze et al., 1999], should soon provide greater spatial resolution of deformation and strain accumulation along the CSZ.

For those who like the extra math as proof of findings the full report from Berkley is here. And this report is from 2000 I believe.

For those who don't know, a fault like the San Andreas which everyone in the US has heard about is where the plates are moving horizontal to one another. A subduction zone is where one plate moves under another one. This is what happened in Japan. These are the ones which have the huge potential for damage as well as tsunamis since a lot of energy can be released all at once. Plus have the upwards or downwards thrusting motion of the earth when they do release.

To see what the subduction zone looks like in both Oregon and Vancouver, here is a comparison image. Note the subduction is at a greater angle in Oregon, thus probably where the more damage will occur.


[atsimg]http://files.abovetopsecret.com/images/member/cb54c7f90964.gif[/atsimg]

Here is another image which shows exactly where the biggest areas of strain are and the direction it is coming from:

[atsimg]http://files.abovetopsecret.com/images/member/65710738cc33.gif[/atsimg]

Until last week, all of this info was just yeah, OK. It's gonna happen one day, but let's not worry about it now if we don't have to. I think we all should have a better understanding of the consequences now of such an event occurring. Unfortunately, it may be too late to put into place the needed engineering and preparedness plans that would be helpful to avoid a huge tragedy.

Nevada quake...just updated from 3.2 to 3.5....

I know it is small but anyway....

Nevada

reply to post by borutp


I was just about to post the link and say Nevada has been having small Earthquakes over the past few days. This 3.5 within the last hour proves of more instability.

Originally posted by borutp
Nevada quake...just updated from 3.2 to 3.5....

I know it is small but anyway....

And just a 5.0 in the Dominican Republic. I hope the close moon this weekend doesn't set this off like it possibly is setting other things off....

Thanks for the link to your thread...
And like the guy from the video said
it might be Calif that gets it in light of the recent fish die off as well as whales coming into shore down in San Diego

guess we'll know but this time next week right?

reply to post by DaddyBare


I hope not. But then again. It;s not looking good. And the moon thing certainly isn't gonna help.

If you start drawing a square on a map from Chile, to New Zealand, to Japan, and then keep the line measurements relatively equal, you'll get a fourth point within The U.S. I believe. It looks like a tilted square. I was bored and curious how it would line up.

- Dredge

I hadn't thought about it until I saw the video, but it has been making a clock wise circle around the Pacific.

Originally posted by DaddyBare
Thanks for the link to your thread...
And like the guy from the video said
it might be Calif that gets it in light of the recent fish die off as well as whales coming into shore down in San Diego

guess we'll know but this time next week right?

Man it's not looking good !

Defo seems to be some sort of chain reaction.

I'm certainly no expert on any of this, but would it trigger Cascadia ?? All chat seems to be on California, but I just wonder about Seattle as well ??

But hey, I know nothing

reply to post by uk today

That's what my concern is. The report I linked from Berkley says this about it:

A conventional model for strain accumulation at a subduction zone assumes that the plate interface slips at the long-term convergence rate at great depths but is fully or partially locked at shallower depths [Savage, 1983]. A model with 10$^circ $ dipping megathrust, a 100-km wide locked zone and a 75-km wide transition zone, where aseismic slip increases linearly with depth until it equals the plate convergence rate, adequately explains crustal shortening and vertical uplift observations in western Washington [Savage et al., 1991]. Similar models are consistent with deformation observations in Vancouver Island, vertical uplift along the CSZ margin, and thermal modeling [Flück et al., 1997].

Horizontal deformation within the southern CSZ is more poorly known. Between 1987 and 1999, the U. S. Geological Survey (USGS) used GPS to recover the positions of survey benchmarks in this region previously measured by triangulation, trilateration, or GPS techniques. We use these observations to estimate horizontal strain rates, which indicate that strain is accumulating everywhere along the CSZ from Cape Mendocino to the Strait of Juan de Fuca and do not rule out the possibility that the entire CSZ could rupture in a major M$sim $9 earthquake [Murray and Lisowski, 2000].

Since the entire fault is around 650 miles long, the estimates are...if this goes...that the quake could last upwards of at least 2 minutes as the release happens along the entirety of the fault. And the CSZ runs from Northern California up to British Columbia. Seattle would be hit, but Portland could well get the worst of it.

reply to post by webpirate


When I visited the Seattle area I noticed the evacuation route signs, obviously to get people to higher ground.
Lets hope they never have to be used

In fact with this Super moon coming, lets keep our fingers crossed for the weekend ahead. Cos with some of the threads I've read on here recently, we may need Lady Luck to shine down on us !!

Is it Monday yet ??

reply to post by MamaJ


Right, like mamaj said, there are being earthquakes (even if they are little) in alot of places in the U.S. Like California for example.