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1700 Cascadia Earthquake (wikipedia.org)
132 points by Hooke 5 months ago | hide | past | favorite | 115 comments

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 important thing to note about that remark is that, needless to say, Murphy really said it, and stood by it in the fact-checking process—so, clearly, fema is anticipating that the region will be in very grave shape.

> That said, “toast” is not what you would call a precise description, so let me be more specific. What Murphy did not mean is that everyone west of I-5 will be injured or killed; fema’s casualty figures, while horrifying, amount to under one-half of one per cent of the population of the region. Nor did he mean that every structure west of the interstate will fail

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):


For instance, look at page 3 of the pamphlet:


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:


For God's sake, just quote the whole thing. You really broke it off mid-sentence?

If including "a million buildings destroyed" (or whichever other part you felt you couldn't include) would make your comment seem less devastating, it just isn't that devastating. It's fine. Representing things accurately is more important than... whatever we were hoping to achieve there. Seeming cool for knowing the original article was BS, I guess?

It's a good article! I don't think it's BS. I might think that if I read your partial excerpt, but that's a problem with the excerpt.

that was a misrepresentation of the linked article

Fun song by Tacocat inspired by this article: https://www.youtube.com/watch?v=DJH1WKSugNo

I saw them perform it at a concert in front of the Space Needle. Really felt I was tempting fate there.

That Jazz Bass is so damn minty fresh; honestly, you're pretty lucky that alone didn't cause the big one!

From that article:

> fema projects that nearly thirteen thousand people will die in the Cascadia earthquake and tsunami.

From the rest of the article, it seems that this estimate of deaths is too low by an order of magnitude. More people died in the Fukushima earthquake, and that is in a country that is probably the most earthquake ready country in the world.

If you only have 15 minutes from the start of the earthquake to when the tsunami rolls in, given the density and the lack of preparation, I could easily see several 100 thousand people perishing if not a million.

I don’t know about how this would impact the estimates, but the Pacific Northwest differs from Japan in that the largest population centers — Vancouver, Seattle, Portland — are not exposed to the open ocean.

Seattle also rises very quickly from the ocean. Take a look: https://en-us.topographic-map.com/maps/na3/Seattle/

With the exception of the international district, all the low-lying areas are industrial in nature.

"Drumlin" is the fun word for this geology, from what I understand. https://youtu.be/oSSxdogrv1s?t=189

Right, in Oregon the coastal areas mostly rise quite quickly from the beach and are relatively sparsely populated. The more populated areas of Portland, Salem, Eugene, etc are well away from the ocean, so a tsunami is unlikely to kill very many people here.

The population isn't really coastal. There will be a lot of casualties along the coast, but it is sparsely populated. The overall number should be much lower than the Tohoku quake. Some other estimates have the number considerably lower than FEMA's.

That figure comes with a caveat that's mentioned towards the end of the article:

> As for casualties: the figures I cited earlier—twenty-seven thousand injured, almost thirteen thousand dead—are based on the agency’s official planning scenario, which has the earthquake striking at 9:41 A.M. on February 6th. If, instead, it strikes in the summer, when the beaches are full, those numbers could be off by a horrifying margin.

Thirteen thousand sounds like a best case scenario. If it happens 4th of July weekend when a million people are on the beaches all up and down the west coast, that could cause orders of magnitude more fatalities.

there is never a million people on the oregon coast.

The problem is if the entire west coast adds up to 1 million people at the beach it might make very little difference which state their in. A 7pm July 4th quake resulting in a massive Tsunami would be vastly more deadly than an identical 4am quake the next day.

If there were ever 1 million people heading to the PNW coast collectively, even on 4 July, the PNW would know it. Routes like the 26 out of Portland or the redwood highway in Oregon / California cannot handle that much traffic. The road to Gerlach, NV gets jammed up by Burning Man traffic, so that should give a good estimate of how many people there can possibly be out there.

Also, unlike in California or the East Coast, these are not quick jaunts to the ocean.

You misunderstood, natural disasters don’t care about state lines or even national borders.

It’s likely no one state adds up to 1 million people, but collectively people at in or near pacific ocean in the US, Canada, and Mexico are at risk. So, if you want to understand the risk from such an earthquake you add everyone together.

If this is the case, it seems like you could get a lot of bang for your buck by building up a beach evacuation infrastructure.

All you really need to do is get inland, and usually not very far.

In this sample evacuation map for Ocean City WA, the higher ground is within half a mile of a good chunk of the coast, and nearly all of the coast is a mile from higher ground. https://www.dnr.wa.gov/Publications/ger_tsunami_evac_oceanci...

All along the Oregon coast are signs indicating where the tsunami impact zone is, and I think there are also alarms in a lot of towns too.

It's a fantastic article, which also won Kathryn Schulz and the New Yorker a Pulitzer!



And Peter Watts' Starfish, from the web site of the author https://www.rifters.com/real/STARFISH.htm

That's the next earthquake.

And Pacific Northwest Seismic Network blog


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 than a few weeks later, I found myself sitting on the 4th and uppermost floor of a 100+ year old brick building, precisely where that fault line was drawn, as the floor started bouncing, then swaying, then the ceiling lamps were swinging back and forth so violently that they were hitting the ceiling on either side, and interior brick walls started to give way.

I worked in that building for another year and a half after that February 2001 6.8 magnitude Nisqually Quake[1], and every time a truck bounced down the potholes of 1st Avenue South, and the office floor bounced, my palms would sweat.

[1] https://en.wikipedia.org/wiki/2001_Nisqually_earthquake

My wife was a student working at the Geological Survey of Canada on the 13th(I think?) floor of a building in down town Vancouver. She tells me that the building got swaying pretty good and the geologists were running around cheering "geology in action" and such. There was a memo on the following Monday about appropriate behaviour in an emergency. :-)

(For myself, best I can figure, I was on a bus and didn't notice a thing.)

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.

Funny thing is, I moved to the bay area shortly after the Nisqually quake, and still haven't been in a "real" quake. I guess the closest was the Napa quake which was a 6.0 and ~80 miles away from my house on the peninsula. My home was built in 1947 so I'm sort of living under the "it's lasted this long.." premise w/r/t construction.

Couple other quakes happened since I moved here, but I was out of town for one reason or another. I even was in eastern France when they got hit by an extremely rare earthquake in ~2004.

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

When the "big one" hits the pacific NW, bridge design is not going to save significant areas from complete destruction.

I am talking about the Cascadian Subduction Zone letting go which happens every 200 to 1200 years (41 times in the last 10000 years). The last time this happened, in 1700, there was a 9.0 earthquake, a 100 foot tsunami and the coastline dropped several feet.

There is about a ~10% chance this will happen again in the next 50 years. If it does, large areas will be completely unprepared and a very large number of people will die.

Not to mention that a very large number of homes in Western Washington are at least 80 years old. The house I live in was built in 1919. It's wood construction and has been gutted/remodeled, but it's also been added onto at least once and has no real foundation, but I think it might be a pier and beam type. An earthquake of large size, 7.0+ will probably cause major damage. For reference, I live near Chehalis, WA.

Post and pier foundations aren't ideal for earthquakes. In general though, wood performs better than masonry as a quake resistant building material because it can flex.

That is quite true. Unfortunately, most of the communities here still have a large number of brick buildings since they were founded at least 100 years ago, if not much longer.

I was right on top of the Northridge quake which was a 6.7 magnitude but more interesting is the horizontal acceleration:

Nisqually: .3g

Northridge: 1.82g

At the time we were told to head for the door frames which was like trying to run in a bounce house.

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 preparation in advance. It is not unreasonable to predict it will be the biggest natural disaster in American history by orders of magnitude.

Here is the best attempt I've seen so far to novelize what will happen in Portland. While obviously speculative, it's all very much based on the evidence at the time and I think does a better job of describing what will happen than just reading the dry (and usually incorrect because they assume supporting infrastructure) reports from the utility companies on how long they think it will take to, for example, repair the transmission lines. If you live in Portland, I implore you to sit down for an evening and take the time to digest this:


Don't panic, but take this seriously, this is a scientifically verified thing that will happen. It is never too early to consider things like earthquake retrofitting your home (bolting the frame to the foundation) and preparing emergency supplies like properly stored food and water. If you're on the coast, memorize your escape route, you won't have time to look it up and your phone won't work anyways.

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 simulation excercise carried out between the Washington and Oregon governments and FEMA.[3]

This will be a huge disaster, but our government and institutions are not apathetic to it.

1. https://www.newyorker.com/tech/annals-of-technology/how-to-s...

2. https://www.seattle.gov/Documents/Departments/Emergency/Plan...

3. https://www.fema.gov/press-release/20210318/emergency-manage... (a 2022 exercise is planned)

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:


I recently listened to the excellent "Fault Lines"[0] podcast from CBC podcast by seismologist Johanna Wagstaffe.

It describes the anticipated impact of the impending megathrust earthquake by examining the first moments, hours, days, etc after the event.

[0] https://www.cbc.ca/listen/cbc-podcasts/147-fault-lines

Here is an excellent lecture on the subject from CWU professor Nick Zenter. If you watch this there is a good chance you'll decide to watch all of his lecture on the channel. Very enthralling.


Nick’s geology talks are a near-perfect mix of academic science, and dynamic storytelling.

Love Nick Zenter! He has a great podcast too! I’d love to see his talks in person one day.

I watched this yesterday. It was quite interesting.

Note that Washington deployed the ShakeAlert earthquake early warning system just yesterday--here's how to enable it on your phone: https://mil.wa.gov/alerts

> 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?

The Earthquake warning system works through the fact that the signal travels faster than the ground waves. So, earthquake occurs and is detected. A warning is sent out. The amount of time between the warning and when you feel shaking is entirely dependent on how far you are from the epicentre. It won't give you much time, but it should be enough to get under a table, or to move away from windows that could break or things that could fall on you.

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.

...and British Columbia did its first test of its public alert system today. (Cell/LTE based). Timely?

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 see folklore and geology intersect.

> 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...

The impressive thing about the Crater Lake/Mount Mazama eruption is that you can still find the ash layer from it in locations hundreds or even thousands of miles away. There's an 8 inch layer visible in many locations in the Okanagan Valley of Northern Washington, which is about 500 miles away by car.

[1] https://en.wikipedia.org/wiki/Mazama_Ash

I'm pretty sure these intersections are often coincidence. There are enough myths across enough cultures that you're bound to find some with similarities to real events. For example: if the story of Sodom and Gomorrah had been a Klamath myth instead of a Hebrew myth, people would claim that it was from the eruption of Crater Lake. The same goes for pretty much any prehistoric flood.[1]

1. https://en.wikipedia.org/wiki/Flood_myth

There really was a worldwide flood. It did not recede; all the water is still there. Instead, people had to abandon where they lived and move uphill.

It didn't happen all in one day, or year. But there were many places where the water moved inland by three feet per year; any beach one knew as a child was gone by adulthood.

Millions of square miles of what was lowland is now underwater -- the region between Indonesian islands; for hundreds of miles out to sea from Viet Nam all the way up to Korea; all the space between Australia and New Guinea; thousands of square miles off India; the whole Persian Gulf; England and Ireland were not islands; from Florida to Louisiana; from Argentina out to the Falklands.

These places were prime habitat (possibly excepting near the Falklands, and northern England), so not unpopulated.

It seems significant that the oldest known civilizations, in Mesopotamia and the Indus valley, arose immediately uphill from especially major inundations. Australian oral records have precise accounts of conflict resolutions over people moving uphill into land already occupied for 40,000+ years.

I live in Portland and have a slide-in truck camper on my property. I use it for camping of course, but it is also part of my earthquake preparation plan. It is solar powered but also has a built-in propane generator. It is fully self-contained with all the comforts of home including fresh water storage, a galley with oven, stove, freezer and fridge. A bathroom plus a hot shower, comfortable bed, large pantry, closet, etc.

It sits on a 3500 diesel truck that can go just about anywhere.

I know this solution is not practical for everyone. But it is always fully fueled, fully stocked and offers considerable peace of mind. If you have been on the fence about buying an RV, think of it from this angle.

This type of stuff is what always made the west coast unappealing. Where I live, disaster is a bad ice storm, blizzard or localized flooding.

Complete devastation just isn’t my thing.

Yeah, but this isn't like living in Tornado alley or the east coast where there is a hurricane season. I live in Portland and we don't have any natural disasters unless a major earthquake does happen or a volcano comes to life. But let's be realistic, what are the chances of that happening in our lifetimes? It's not like this is an every year thing like tornadoes, hurricanes, blizzards, etc. Complete devastation from hurricanes and tornadoes and flooding is much more likely than huge earthquakes and volcanoes.

Tornadoes are pretty rare (and localized) outside of certain areas. Blizzards--other than a bad one if you live on the coast--are mostly a stay at home until it's over event. Hurricanes/floods are definitely in the southeast and can come up the coast as in Sandy. But this again mostly involves having a house somewhere that's not overly exposed to flooding if there's a lot of rain.

But yes. There's some balancing of unlikely but major natural disasters and fairly routine bad weather events.

From a natural disaster perspective you're probably best off in the desert Southwest.

I wish it kept more people away.

Our sailboat is our earthquake kit. It only holds* 15 gallons of freshwater, but has a functional kitchen and bathroom, and we can go 1000 miles north or south of here in a week, regardless of fuel or road conditions.

If covid had gotten India/Italy bad, our plan was to evacuate to Hawaii or Mexico.

*not including extra packaged water, boats can hold quite a bit

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 history, one day before (Saturday) , there was one big earthquake(8 1-8.3, X in mercalli m) 400 km North (city of Concepción) , that cut the communications and roadways from the capital to the south of the country. On Sunday, a second earthquake of similar magnitude struck, that finished destroying the remaining buildings in the location,but nobody died on that second earthquake because everyone was outside,for obvious reasons. Finally, the big one started not on Valdivia (300 km South) but the fault line extended 1000 km reaching Valdivia and beyond, 135 people died on Japan, Valdivia itself sunk permanently 2.7 meters (8 feet) ,one chain of lakes got their exit rivers blocked, so the water level was rising rapidly and if overflowed, it would flood again the same areas affected by the earthquake, so a joint operation between military and private parties were set up to try to unblock the whole system (they succeeded), there was a case of human sacrifice, trying to calm the fury of the gods that caused such destruction, it was wild

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.

There is a fantastic set of videos on the geology of the Pacific Northwest by Nick Zentner available on Youtube:


Edit: I'm nowhere near the area (I'm in Scotland) but I find the series absolutely fascinating.

Zentner's videos are forking fantastic. There is some really mind blowing stuff about the PNW geology.

For example, Did you know there's a connection between Yellowstone, Smith Rock in Oregon, and Liberty Gold in central Washington?

The possible connections between columbia river basalt and yellowstone is also very interesting.

It's just a fantastic place to be for geology.

Reminder to folks that water, food, blankets, and tools are reasonable things to have stored away if you live in the PNW (or anywhere, really), and are relatively low maintenance to store.

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.

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.

There's been quite a bit of tremor activity in the last month. I don't know if it is a change from before, but over the last month (2021-04-01 - 2021-05-06) basically everything west of I-5 from Portland, OR to Redding, CA has had deep tremors.


I live on the 8th floor of an old 60's Vancouver 18-story apartment complex. I'd like to be out of here sooner than later, as I suspect this building and many like it will simply collapse entirely when the big one hits. Similar, erm, paranoia is why I would never purchase in Richmond/Delta. Liquefaction of that entire region is possible - not something I like to think about!

Add onto this that many or most of the mountains in the area are active volcanoes that are overdue for an eruption, and the Seattle area could be in for a real bad time over the next 250 years.

The projections of a moderate eruption of Mount Rainier (aka Tahoma/Tacoma) include flows reaching all the way to Renton/South Seattle.

I have not seen anything that indicates Rainier or other volcanos are "overdue" for an eruption. Rainier, like others, goes through periods of greater or lesser activity. It's hard to predict the size of any particular eruption, as we saw at Mt St. Helens in 1980.

The biggest risk from Rainier currently is lahars, aka mudflows. You don't need an eruption for those. The last big one was Kautz Creek in 1947. If you live in one of the valleys around Rainier there's a reasonable chance of seeing a lahar in your lifetime. (Hopefully from somewhere out of harm's way.)

“Most” of the mountains are not active volcanos. There are only 4 in Washington: Baker, Rainier, St Helens, Adams but hundreds of other mountains. Rainier is really the only one that poses serious danger to a populated area. Tacoma in particular will be destroyed by lahars alone in a large eruption

There are (at least) five major active volcanoes in Washington. You are forgetting Glacier Peak, an active volcano that is as close to Seattle as Rainier, but not as visible due to its lower elevation.

The biggest ones (>8.5) are on average every 500 years.

Timeline: https://projects.oregonlive.com/maps/earthquakes/timeline

So if we are super-lucky, it will happen in this century, and be smaller.

"Our operating assumption is that everything west of Interstate 5 will be toast."


The author hedged pretty strongly on that statement here: https://www.newyorker.com/tech/annals-of-technology/how-to-s...

> 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 important thing to note about that remark is that, needless to say, Murphy really said it, and stood by it in the fact-checking process—so, clearly, fema is anticipating that the region will be in very grave shape.

> That said, “toast” is not what you would call a precise description, so let me be more specific. What Murphy did not mean is that everyone west of I-5 will be injured or killed; fema’s casualty figures, while horrifying, amount to under one-half of one per cent of the population of the region. Nor did he mean that every structure west of the interstate will fail

Correct. Operating assumptions help in planning disaster recovery operations. For instance, which are the areas that you have a very high degree of certainty will survive? These are the areas in which you want to muster your defenses so to speak.

I read that as, "we can use I-5 as a distribution backbone if we prioritize its repair because it is very unlikely to suffer too much damage." I also assume that simulations indicate it will not need much repair. Bonus points if we've already re-engineered the sections of I-5 most likely to need repair. It could save time later.

So now we can make a plan around what we're likely to have, and if we have more when the time comes it's gravy.

Basically, don't position all your recovery assets and facilities along the 101. Doesn't mean the 101 won't be there, it only means your plan has a smaller chance of falling apart if you position the facilities you'll need along I-5.

I really doubt it. A lot of the land West of I-5 is drumlins/drumlinoids like Fremont Ridge in Seattle. That's solid ground that has been around since the last glaciation and has come through many earthquakes just fine.

On the other hand...If somebody like Brian Atwater said it, that would really get my attention. He's one of the main geologists who tracked down the geological evidence to date the 1700 Earthquake. The force is strong in that one. [1]

[1] https://en.wikipedia.org/wiki/Brian_Atwater

It's a great soundbite, but it loses a lot of context when distilled down.

Most of the infill west of I5 in the Seattle area will probably liquefy, but there's mountain ranges to the west of I5 that would take a hell of a quake to toast.

Yes, I have assumed they meant something more specific, like "every building and road west of I5" (I live only a few miles east, so I doubt I'd be unscathed myself, somehow).

FEMA doesn't care about damage to mountains. They're talking about human-made property and dead people.

The earth will be fine its the humans we are worried about

Specifically, the perpetual habitability for humans

Anything low lying in that area is at high risk in a cascadia quake. Buildings on high ground "only" have the quake risk, which is still significant.

I'm more concerned about the homes that will go up in flames due to ruptured gas lines. With the fire department overwhelmed, the potential amount of toxic smoke/fumes post-quake scares me more than the quake. Assuming I survive, assuming my family/friends do, assuming we all even are happy about being survivors of something so colossal, at such scale...

There aren't many places with natural gas significantly west of I-5 in Washington. There's a main artery down WA-12 to Aberdeen and the harbor, and that's it.

There's no natural gas service anywhere else on the WA pacific coast, nor the northern coast of the olympic peninsula (Sequim, Port Angeles), or the west bank of the Hood canal. The entire Olympic Peninsula is without natural gas except for one metro area. They actually have to haul tanks full of the stuff to the paper mill in Port Townsend to use.

Yep, this is what always gets me about the original quote - the peninsula _does_ exist, and while the damage will be very significant, a lot of us will be just fine, and most assuredly not toast.

The aftermath will suck, however.

The worst smoke can do is suffocate you, or raise your risk of cancer, but you can move out of harm's way.

The quake itself and tsunami risk is the dangerous part for most people.

I dont think smoke is what you should be worried about during a natural gas explosion.

Nonetheless, id still be worried about things that will kill me, even if its not in the next 10 seconds. Dead is still dead.

The fire and explosions are dangerous to be sure, but the OP specifically called out smoke.

It's a weird statement to make, because the route of I5 is fairly arbitrary, geologically speaking. Lower parts of downtown Seattle may be at risk, but is upper Queen Anne hill? Ballard may be partially screwed, but Crown Hill is hundreds of feet higher in elevation. That assumes that Puget Sound even generates a large Tsunami based on an offshore quake.

If we're talking about Oregon it gets even weirder since the population centers have a coastal range in between them and seawater. I don't know enough about the various fields involved to know if the Columbia river's level would raise catastrophically in such a scenario.

> because the route of I5 is fairly arbitrary, geologically speaking

You sure about that? From Olympia to the Oregon border I-5 sits on the lowest, flattest stretch of land between the coastal range and the cascades. That's why it keeps getting flooded out by the Chehailis river.

To the north, through Whatcom County the route is anything but geologically arbitrary: it's the unique route that required the minimum amount of blasting into Chuckanut rock.

Parent post seems like a pretty city-centric view of the world. The dozen or so miles that pass through Seattle might be arbitrary to within a Seattle-diameter, but that's an irrelevantly small part of the freeway.

There is not a significant tsunami risk from a Cascadia subduction zone earthquake in Seattle, due to its topography and distance from the fault. The biggest risk in that regard is from the Seattle fault, a thrust fault, that runs through the middle of Elliott Bay, which can both generate large water displacements and can cause large subsidence of the land (i.e. it can literally sink a dozen feet during an earthquake). Seattle is geographically very vertical, and heavily shielded from the open ocean, which limits the tsunami effects.

The real risk is civil engineering in nature. While the fault is some distance away, it will shake hard and for a long time. Unreinforced masonry will probably be destroyed, and Seattle has a lot of old masonry in some neighborhoods. Some older structures not up to the current seismic code will likely fare poorly. Seattle has had enough local 7+ earthquakes that a distant offshore 8-9 won’t feel too much different, but the shaking time will be much longer. Landslides are undoubtedly a risk.

Portland will likely fare much worse than Seattle. A modern steel or wood-framed building constructed in the last 20 years will very likely survive almost anything, they are built for it. Older steel and wood buildings that are still standing have already been through some earthquakes; not as large but they won’t immediately collapse.

The real problem will be restoring infrastructure in the aftermath.

Not sure if this is what they're referring to, but in the downtown area I-5 traces the original shoreline. Everything to the west is fill from Seattle's many regrades. https://youtu.be/oSSxdogrv1s?t=519

The danger zone in Western Oregon is places like the Tualatin Basin (which is all West of I-5). This is the location of things like all of the Intel Fabrication plants in Oregon, Nike World Headquarters, etc. The entire basin will liquefy in the event of a giant earthquake.

Lots of unreinforced masonry buildings are in these regions. The shaking from such a large quake will go on for minutes and make them crumble.

This shouldn't be in the article. It's unscientific, non-technically, and pretty much meaningless.


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.

>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.

In Oregon, the land to the west of I-5 is clay silt from the Missoula Floods that came down the Columbia Gorge 13,000 - 15,000 years ago. The clay silt is expected to completely liquefy in the event of a major earthquake.

What impact do you think complete liquefaction will have on people and buildings?

Widespread death and destruction. Seriously, other than the houses on Cooper Mountain, I don't seriously expect anything to still be standing in the Tualatin Basin when the big one hits.

Has there been another earthquake where a populated area sat on geography similar to the Tualatin Basin?

It's not a science paper. It's in the New Yorker. It's supposed to be interesting. It also features great lines such as: "Oh, shit, Goldfinger thought, although not in dread, at first: in amazement. " "As Goldfinger put it, “In the late eighties and early nineties, the paradigm shifted to ‘uh-oh.’ ”" "...magnitude 5.0, magnitude 4.0, magnitude why are the neighbors moving their sofa at midnight"

It is quoted on wikipedia. An online encyclopedia.

I'm not sure I would call statements by a FEMA director "unscientific."

You aren't actually making a point.

Are you saying that ""Our operating assumption is that everything west of Interstate 5 will be toast" has scientific value?

Are you saying that because of someone's tittle they are incapable of saying something hyperbolic?

Do you disagree with my word use? What is a better word?

I was actually making the point that the FEMA Director for the Pacific Northwest probably knows a lot more about the scenario in question, and that his statement may be grounded very deeply in fact such that it's not hyperbolic at all.

Neither are you

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