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1700 Cascadia Earthquake

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Re: 1700 Cascadia Earthquake

#91

Post by bawolff »

99_00 wrote: post #83
bawolff wrote: post #23

Earlier quoted context omitted.

Really? I don't know if the statement is backed up by science, but its a falsifiable empirical prediction. It is entirely within the realm of science to make predictions that certain geographic regions will have significant structural and human damage in the event of some hypothetical natural disaster.

>It is entirely within the realm of science to make predictions that certain geographic regions will have significant structural and human damage in the event of some hypothetical natural disaster. I agree. But that's not the same as saying it's "toast".

Its a colloquialism for destroyed. Would you object if he said "utterly destroyed" instead? It means the same thing.

Maybe you think its inappropriately informal, but that is a stylistic concern, not a science concern.

Re: 1700 Cascadia Earthquake

#92

Post by 99_00 »

bawolff wrote: post #91
99_00 wrote: post #83

Earlier quoted context omitted.

>It is entirely within the realm of science to make predictions that certain geographic regions will have significant structural and human damage in the event of some hypothetical natural disaster. I agree. But that's not the same as saying it's "toast".

Its a colloquialism for destroyed. Would you object if he said "utterly destroyed" instead? It means the same thing. Maybe you think its inappropriately informal, but that is a stylistic concern, not a science concern.

>Its a colloquialism for destroyed

That's debatable. It can mean anything from doomed to in trouble.

IDIOMS FOR TOAST be toast, Slang. to be doomed, ruined, or in trouble:

>Would you object if he said "utterly destroyed" instead?

Yes I would object.

Does it mean everything west of I5 is going to fall into the ocean? All human structures are going to be levelled? Only structures over 2 stories not made out of wood will be levelled? Or just that everything west of I5 will have more damage than everything east.

And I doubt that EVERYTHING east of I5 is going to share the same fate. The I5 is a human made road, not a geographic feature. It doesn't control earthquake outcomes.

Re: 1700 Cascadia Earthquake

#93

Post by dave333 »

Maybe they should build some large reinforced concrete buildings that can act as tsunami shelters and also fulfil a secondary function such as public library (do they still have those) or offices/shops or whatever. Maybe 100 ft high would be enough, but design it so that people can survive inside it even if it is temporarily overrun by the tsunami.

Or you could build a larger number of small reinforced shelters that would be designed to be overrun but would keep people alive until the tsunami retreats.

Re: 1700 Cascadia Earthquake

#94

Post by kevinkeller »

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…

> According to the myth of the Klamath Indians, Llao, the chief of the Below World, standing on Mt Mazama, was battling Skell, the chief of the Above World, who stood on Mt Shasta in California, about a hundred miles away (Clark 1953). They hurled rocks and flames at each other, and darkness covered the land. The fight ended when Mt Mazama collapsed under Llao and hurled him back into his underworld domain. The large hole that was created then filled up to form Crater Lake.

> This sounds like an eye-witness account of such an eruption, and it undoubtedly is, for Indian artifacts have been found buried in the Mazama ash. The eruption has been radiocarbon-dated to about 6500 years ago on the basis of Indian sandals found in the ash, but had no datable materials been found, this myth alone would have served to date the eruption as post-Pleistocene, because this part of the world was first inhabited by people who crossed the Bering Land Bridge and migrated down through Alaska and Canada into the northwestern United States.

Geomythology: geological origins of myths and legends https://sp.lyellcollection.org/content/specpubgsl/273/1/1.fu...

Re: 1700 Cascadia Earthquake

#95

Post by 29athrowaway »

longemen3000 wrote: post #87
29athrowaway wrote: post #64

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…

I was near the epicenter of the Chilean earthquake of 2010 (8.8),and my grandfather was in the 1960 one. The main mayority of the casualties in both earthquakes were caused by tsunamis (its really a bummer that Chile is basically a long strip of coast) we were lucky (in 2010)because the nearest big coastal population center was inside a bay, so the wave didn't hit directly. the 1960 earthquake has a very interesting…

Most of the destruction in the 2010 Chile Earthquake was caused by people themselves: looting, arson and violence.

The Bachelet administration was hesitant to mobilize the army due to the potential political cost (i.e.: bringing back memories of the Pinochet regime), so they took several days to make that decision and in the meantime things went completely out of control.

The same administration was also hesitant to evacuate the residents in the Juan Fernandez Islands, effectively causing many of them to die when the tsunami wave hit.

Re: 1700 Cascadia Earthquake

#96

Post by ac29 »

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.

The pacific northwest gets hit by earthquakes quite often too: https://pnsn.org/

Re: 1700 Cascadia Earthquake

#97

Post by irrational »

gammarator wrote: post #31
bmmayer1 wrote: post #2

Would not be complete without this fantastic article: https://www.newyorker.com/magazine/2015/07/20/the-really-big...

I think that article is best paired with this followup: https://www.newyorker.com/tech/annals-of-technology/how-to-s... in particular this hedge: > Perhaps no line in the entire six-thousand-word piece attracted as much attention as this declaration by Kenneth Murphy, head of the fema division responsible for Cascadia: “Our operating assumption is that everything west of Interstate 5 will be toast.” The first importa…

I live in the Portland area, west of I-5. The reason for this became clear when I saw this article (which I learned about here on HN):

https://www.usgs.gov/news/volcanoes-vineyards-new-geologic-m...

For instance, look at page 3 of the pamphlet:

https://pubs.usgs.gov/sim/3443/sim3443_pamphlet.pdf

To the west of Portland we see Dark Gray which is Basalt (if you've ever driven through the tunnel and up and over the west hills to the western suburbs of Portland, you have driven through the basalt region) and then there is a big light yellow oval that is labelled Tualatin Basin. What is the light yellow according to the legend? It is surface deposits. Long ago this was a basalt bowl. Then a giant flood came down the Columbia river gorge and dumped hundreds of feet of clay silt into the bowl. When you are standing in Beaverton, Hillsboro, Bethany, etc. you are standing hundreds of feet above the original valley floor.

Now look at the map again. The basin is pretty much all to the west of I-5. If you live in the basin you are screwed when the big earthquake hits (the one exception is that hill of basalt rising like an island in the middle of the basin - that is Cooper Mountain, it's no coincidence that the houses on top of Cooper Mountain are where the rich people live). What is going to happen is the earthquake waves will come in and bounce off the basalt on one side of the bowl and reverberate back to the basalt on the other side. The waves will go back and forth in the bowl and liquefy all of that old clay silt. Just like this:

https://www.youtube.com/watch?v=3NSXmTfASM0

Re: 1700 Cascadia Earthquake

#98

Post by xucheng »

hadlock wrote: post #89
cvdub wrote: post #82

Earlier quoted context omitted.

> Washington deployed the ShakeAlert earthquake early warning system just yesterday Do you know how the early warning system works? How much advance warning do they expect to give?

Tokyo got nearly 30 seconds warning for the Fukushima earthquake. I have no idea how well Washington's system works, but I would imagine that someday it'll be as good as Japan's was in 2011

In order for this happens, we really need an unified earthquake early warning network in entire west coast connecting from BC, Canada all the way to Mexico. It seems that all the existing systems are only regional so far. At the same time, we probably need to drastically increase the density of the seismometers.

All in all, the earthquake early warning system in North America still lies far behind to say the system in Japan.

Re: 1700 Cascadia Earthquake

#99

Post by irrational »

connor4312 wrote: post #57
kyledrake wrote: post #38

It's very difficult to describe how bad this earthquake is expected to be for a large swath of the Pacific Northwest when it happens again (and it's when, not if). It will be similar to Fukushima except absolutely nothing in the region is designed for earthquakes of this magnitude, not to mention the expected tsunami. Given the massive investment required and lack of motivation to do it, there will be almost no prepa…

This is a little pessimistic.[1] As a percentage, few people are expected to die, and modern buildings are unlikely to collapse. At least in the Puget Sound region, buildings codes have been seismically sound for several decades, and old buildings and infrastructure have gradually been retrofitted[2]. There is _already_ preparation being made with the aforementioned programs, and notably the Cascadia Rising simulatio…

Does the Pugent Sound have anything like the Tualatin Basin?

Long ago a giant flood from the columbia river gorge filled a large basalt valley with hundreds of feet of clay silt. Today there are many hundreds of thousands of people living and working on top of the clay silt, including the entirety of Nike world headquarters and the majority of Intel's fabs.

When the earthquake hits, the entire basin is predicted to liquify, just like this:

https://www.youtube.com/watch?v=3NSXmTfASM0

Re: 1700 Cascadia Earthquake

#100

Post by irrational »

dave333 wrote: post #93

Maybe they should build some large reinforced concrete buildings that can act as tsunami shelters and also fulfil a secondary function such as public library (do they still have those) or offices/shops or whatever. Maybe 100 ft high would be enough, but design it so that people can survive inside it even if it is temporarily overrun by the tsunami. Or you could build a larger number of small reinforced shelters that…

They don't need this along Cascadia. All of the major population centers are 60 miles inland (in between the coastal and cascade mountain ranges). There are just very small town on the coasts and the coastal mountain range rises very quickly from the coast. You can get to high ground from just about anywhere on the coast fairly quickly.
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