Cascadia subduction zone article in The New Yorker

[seannx]

From Facebook...
http://www.iflscience.com/environmen...011-earthquake
The amateur video of the ground opening and closing is pretty scary.

I was on a construction job in Green Valley, CA (near Fairfield) when the Loma Prieta quake hit, and remember watching the sliding glass patio doors distorting to a parallelogram shape, and then going back to normal. A big wave moved across the back yard, rocking the swimming pool, which sloshed out half the water. If you've never experienced a bigger earthquake, it is very unnerving. The smaller ones that you notice, but do no damage, are almost kind of fun, but only after they pass, and you know they have been minor.

[Glennwillow]

Sean,

I was in downtown San Francisco on the lowest floor of the Mascone Center when the Loma Prieta earthquake hit. This was my first earthquake and because I had no experience with anything like this, I was too stupid to be afraid. I was standing there, rocking back and forth as the floor was moving on the rollers of the building, watching the trusses above flex. I am an engineer, and in my mind I was thinking, Oh, cool! Look at those trusses flex with the movement of the floor and building -- this is like the ultimate science class! Then someone in the group yelled "Earthquake!" and grabbed me to get to a stronger, better reinforced area of the building. I was standing next to a tall piece of equipment weighing about 1500 lbs, so it was a good thing he grabbed me and got me to move.

Now, whenever I feel an earthquake, I have a much more visceral reaction a whole lot closer to fear.

- Glenn

[KevWind]

Originally Posted by seannx

Yes, two little concerns that would result in massive destruction.

Yes my attempt at humor. Although honestly even though aware of the possibility I can honestly say it was not really something on the mind and was never any kind of motivation to move.

Originally Posted by kydave

VEI – 8 eruptions are colossal events that throw out at least 1,000 km3 (240 cu mi) Dense Rock Equivalent (DRE) of ejecta.

VEI – 7 events eject at least 100 cubic kilometres (24 cu mi) DRE.

VEI – 7 or 8 eruptions are so powerful that they often form circular calderas rather than cones because the downward withdrawal of magma causes the overlying mass to collapse and fill the void magma chamber beneath.

By way of comparison, the 1980 Mount St. Helens eruption was a VEI-5 with 1.2 km3 of ejecta.

There was a 5.1 quake right before the eruption. That's not much as earthquakes go.

I was actually cross country skiing on St. Helens 2 weeks prior the the first uptick in seismic activity about two months before the actual eruption

[D. Shelton]

Originally Posted by Basalt Beach

A friend sent this article to me. Living in the east, we most often hear and read about "earthquakes and California". I was not aware the Cascadia Subduction Zone nor the potential magnitude of an earthquake in the region. The potential devastation described in the article is beyond comprehension.

http://www.newyorker.com/magazine/20...really-big-one

Oh yeah, it's big and scary. Seattle in the path of a giant lahar if Ranier decides to blow . Among other things that section of the 'ring of fire' has to throw at us....

[steveb2223]

Please forgive the long quote, but this is the part that upsets me most:

"The last person I met with in the Pacific Northwest was Doug Dougherty, the superintendent of schools for Seaside, which lies almost entirely within the tsunami-inundation zone. Of the four schools that Dougherty oversees, with a total student population of sixteen hundred, one is relatively safe. The others sit five to fifteen feet above sea level. When the tsunami comes, they will be as much as forty-five feet below it.

In 2009, Dougherty told me, he found some land for sale outside the inundation zone, and proposed building a new K-12 campus there. Four years later, to foot the hundred-and-twenty-eight-million-dollar bill, the district put up a bond measure. The tax increase for residents amounted to two dollars and sixteen cents per thousand dollars of property value. The measure failed by sixty-two per cent. Dougherty tried seeking help from Oregon’s congressional delegation but came up empty. The state makes money available for seismic upgrades, but buildings within the inundation zone cannot apply. At present, all Dougherty can do is make sure that his students know how to evacuate.

Some of them, however, will not be able to do so. At an elementary school in the community of Gearhart, the children will be trapped. “They can’t make it out from that school,” Dougherty said. “They have no place to go.” On one side lies the ocean; on the other, a wide, roadless bog. When the tsunami comes, the only place to go in Gearhart is a small ridge just behind the school. At its tallest, it is forty-five feet high—lower than the expected wave in a full-margin earthquake. For now, the route to the ridge is marked by signs that say “Temporary Tsunami Assembly Area.” I asked Dougherty about the state’s long-range plan. “There is no long-range plan,” he said."

Willful ignorance and selfishness will kill us.


-- Steve

[SMan]

Looks like a cost of $80K per student (but my math could be wrong). With ever rising taxes it doesn't surprise me it was voted down. I wouldn't choose to live or let my children go to school in Gearhart if the risks are what they claim.

[HHP]

Maybe some perspective. You can probably predict natural disaster almost anywhere. Science is well short of accurate prediction of where, when any will hit next. Nor are the anywhere near capable of knowing how the disaster will play out when they do inevitably strike. In order to get attention, these things are put out in a "you may die tomorrow" context when they have no real basis to suggest immediacy.

[seannx]

Originally Posted by HHP

Maybe some perspective. You can probably predict natural disaster almost anywhere. Science is well short of accurate prediction of where, when any will hit next. Nor are the anywhere near capable of knowing how the disaster will play out when they do inevitably strike. In order to get attention, these things are put out in a "you may die tomorrow" context when they have no real basis to suggest immediacy.

One thing we can be sure of, is that if a tsunami hits, and school children are killed, then people will get upset, and wonder why measures weren't taken.

[kydave]

Originally Posted by seannx

One thing we can be sure of, is that if a tsunami hits, and school children are killed, then people will get upset, and wonder why measures weren't taken.

Change the word "if" to "when" and you are absolutely correct.

No offense, but part of the problem is that word "IF" in people's mindsets.

There is no "IF", only "WHEN"...

I hope no one gets offended by that scientific fact, but "fact" and "when" are important concepts.

[HHP]

Originally Posted by kydave

Change the word "if" to "when" and you are absolutely correct.

No offense, but part of the problem is that word "IF" in people's mindsets.

There is no "IF", only "WHEN"...

"When" is accurate but suggests an immediacy that the geologic record does not. Last great quake in the Northwest was in 1700. Geologists suggest a frequency of 300 to 900 years between events, with an actual average of just under 600 years. You can easily use "when" in talking about the next big asteroid impact or magnetic polarity shift.

[seannx]

Originally Posted by HHP

"When" is accurate but suggests an immediacy that the geologic record does not. Last great quake in the Northwest was in 1700. Geologists suggest a frequency of 300 to 900 years between events, with an actual average of just under 600 years. You can easily use "when" in talking about the next big asteroid impact or magnetic polarity shift.

Dave makes a good point. When is the accurate word. And adding 1700 and 300 (minimum frequency given) gives 2000. Having experienced two "100 year" floods in the Napa Valley, within a couple of years, I don't think that the average approach is necessarily the smartest one to use. It was only after the second "100 year" flood hit, that the risk was taken seriously, and money was spent on appropriate measures.

While I sure hope the next "big one" is a long way off for the San Francisco Bay Area, if I'm around when it comes, I won't be surprised.

[LisaT]

The Cascadia Quake is over-due...so we here, in the Great PacNorthwet, are on borrowed time. The Nisqually Quake was a wake up call for the general public, but city planners in Seattle were already working on scenarios back in 1991...which is when I had to attend a mandatory seminar concerning the risks involved during a potential Mag 10-12 quake, in a high rise. We were informed at that time, that should we be caught in the city during a large quake, we would not be going home anytime soon. Emergency services would be non-existent, the bridges would likely fail, and the tsunami would innundate all but those living on the hills in Seattle. If the ferries survived...they would become morgues. The picture painted at that time, was bleak.

While the damage inflicted during the quake will be great, the tsunami that will follow approximately 15-20 minutes later will be catastrophic. While this state does run tsunami drills routinely throughout the year, there are cracks in the system. The fact that not all the tsunami warning buoys in the Pacific are currently functioning adds to the problems. If one has any doubts as to the potential for damage, and distances that can be travelled by a tsunami, one can look at the Ghost Forest near Copalis.

Now, while the Cascade volcanoes are part of the 'Ring of Fire', they are subject to some different forces. They are representative of what are called 'hot spots'...which move incredibly slowly, as the plates move. It also explains why 'chains' of volcanoes appear...it's the hot-spot's 'trail of breadcrumbs', as it were. It's much easier to visualize what I am talking about when you look at the entire Hawaiian Island chain. Each one of those islands represents a moment in time over a hot-spot...the hot-spot created them.

Now, the Yellowstone Caldera will not become a super-volcano....it IS a super-volcano. And scientists have now been able to map the magma chamber beneath, they have found that it is actually 2x larger than they initially thought. When it goes, it will be an extinction event. But, Yellowstone is not our only super-volcano here in the US. One need only look to the Mammoth Mountain/Lakes area of California to find an equally deadly super-volcano.

Can volcanos and earthquakes be related? Absolutely. Remember, St Helens didn't erupt at first. The magma built up in the volcano's chamber, causing severe deformation of the south side of the mountain...thus making the ground extremely unstable. It was the earthquake that struck, causing the long run-out landslide, releasing pressure against the magma chamber that allowed for the mountain to blow out it's side...thus erupting.

Yes, I know way more about this geological stuff than perhaps I should...but since I live here, I might as well be informed as to the potential of what is going on under my feet. BTW...I get my information from the Pacific Northwest Seismic Network, as well as the USGS WA/OR...not the New Yorker.

[buddyhu]

Originally Posted by HHP

"When" is accurate but suggests an immediacy that the geologic record does not. Last great quake in the Northwest was in 1700. Geologists suggest a frequency of 300 to 900 years between events, with an actual average of just under 600 years. You can easily use "when" in talking about the next big asteroid impact or magnetic polarity shift.

Using the word "when" does not suggest immediacy to me. It suggests inevitability, which is accurate. The content of the article provides a reasonably objective understanding of the variability that is involved when using an arithmetic mean to describe a tendency, while also providing very clear (low) numbers regarding the probability in our lifetimes.

I trust you read the article. What elements of the article leave you feeling that there is undue urgency communicated? I am not seeing it right off.

[robj144]

Originally Posted by HHP

"When" is accurate but suggests an immediacy that the geologic record does not. Last great quake in the Northwest was in 1700. Geologists suggest a frequency of 300 to 900 years between events, with an actual average of just under 600 years. You can easily use "when" in talking about the next big asteroid impact or magnetic polarity shift.

Well, when is definitely a better qualifier than if.

[KevWind]

Originally Posted by HHP

"When" is accurate but suggests an immediacy that the geologic record does not. Last great quake in the Northwest was in 1700. Geologists suggest a frequency of 300 to 900 years between events, with an actual average of just under 600 years. You can easily use "when" in talking about the next big asteroid impact or magnetic polarity shift.

Lets see, 1700 + the short end of the frequency figure 300 would be 2000 as seannx pointed out . I guess whatever "immediacy"the word "when" might suggest, is actually supported by the "geologic record"