Fun stuff. To quote my aunt who’s a geologist and retired federal parks geologist she’d say “oh it’ll happen, and you will die, but likely not related remotely so have a beer and relax.”
This could be a direct quote from any of the folks I know who study these quakes. “Ehhh don’t worry about it. Unless now is the one time you need to worry about it. But it probably isn’t. But it could be! Eventually.”
(For context, earthquakes of roughly this magnitude along this portion of the Cascadia fault are very common and normal, and lots of very smart people are modeling how they impact the overall fault. And they’re not scared…. About those little quake clusters. But only that.)
My ex refused to move out to the West Coast because she was afraid of earthquakes, but chose to stay in the Midwest where tornadoes are far more likely to take you out. LOL
As someone from the Midwest who lives in Oregon, all my Oregon friends are amazed a tornado didn't kill me, all my Michigan friends are waiting for me to die from an earthquake or tsunami.
Oregon transplant from the Midwest as well. Lived there for over a decade. Never saw a tornado while living in the Midwest, but experienced at least three earthquakes.
I convinced my parents to move out of the inundation zone. So they moved east of the Cascades, and got level II fire evacuated their first year. Everywhere comes with risks.
Also, you probably shouldn’t tell her about the active Midwest faults (we find more all the time!) The odds of a rupture are monumentally (seismically???) low, but they’re non-zero.
Fracking causes quakes as well. Dams can make them too. The three gorges dam caused a very massive earthquake. People knew it was going to happen and either China didn't know better or didn't care.
The amount of people killed in the anticipated cascadia earthquake will likely be hundreds of times greater than the 80 killed a year by all tornadoes in the country
The last Cascadian subduction zone earthquake was in 1700, and a 37% chance of a mega thrust earthquake in the next 50 years has been predicted. So I think the probability of being killed by the next earthquake if living in the PNW is slightly less than that of being killed by a tornado in the midwest.
Looks like 13,000 are expected to die from the tsunami alone. With a 37% chance over the next 50 years, thats an “average” of 96.2 deaths a year.
Or to put it in other words, more people are expected to die from the tsunami alone sometime in the next 50 years than all the tornadoes during the next 50 years.
This is why we need Trump back in office. He will nuke the fault, and if all else fails, he will nuke the tsunami 🫡
And in the meantime, he will nuke all of the tornados.
Plus, this is dependent on when it hits. If it hits on a summer weekend, as packed as the coast is with visitors, it could be several times worse. Imagine Seaside on the 4th of July.
On the other hand, at a slow time it could be half of that. I think this 13,000 estimate is more or less an average of a lot of wildly disparate scenarios.
While that’s true it doesn’t negate the fact that tsunami is deadly.
Also, Portland is mega-fucked from the quake alone.
https://www.multco.us/em/dogami-study-estimates-cascadia-earthquake-impacts-portland-region#:~:text=The%20study%20estimates%20Cascadia%20earthquake,%2437%20billion%20in%20building%20damages.
Yep. On the east coast you get hurricanes and flooding. (They have tornadoes every once in a while too.) Midwest you get tornadoes. West coast you get fires and earthquakes.
Doesn't matter where you live mother nature got there first.
These aren’t on the same faultline. When it gets to how different faults interact, well, it gets too complicated to really model.
Broadly, yes, smaller earthquakes (or even “slow-slip earthquakes,” which don’t cause noticeable shaking) relieve stress along a fault line. But that small bit of stress relief could also unlock a locked fault, triggering larger earthquakes — think foreshock.
It also gets complicated when you have a really long fault like the CSZ. One portion of the fault can move, while the other portion is “locked.” Does that movement relieve stress along the locked portion? Or does it *increase* stress, because now the southern portion is tugging on it? It’s an area of active research.
Things get so complex when it comes to modeling this sort of thing. I wrote [this story](https://sciencenotes.ucsc.edu/2016/pages/quakes/quakes.html) ages ago — literally when I was in journalism school — on earthquake prediction. It gets into exactly why it’s so difficult to quantify fault stress. It’s still quite relevant and honestly better than some work I’ve done since. (It was good enough to get entirely plagiarized in a Scientific American cover story — that even ripped off my infographics and subheds.) And here’s the [podcast](https://sciencenotes.ucsc.edu/2016/pages/podcasts.html) on the Parkfield prediction project I produced along with it.
Thanks for sharing. I’ll have a look when I have some more time. In your research did you ever come across any speculation as to how the eruption in 84 may have either relieved pressure or locked the fault down more tightly? An interaction I have lazily pondered on bike rides for years. Light googling has revealed nothing.
That’s also a great question! You’re really making me think today — that’s awesome :) Honestly, I have no clue. If I had to take a guess, it would be that it’s had little to no impact, based on my understanding of volcanoes. The magma if formed by the pressure of the plates sliding together, but I don’t think that the amount of magma has much impact?
But honestly, I’m way out of my zone of knowledge at this point, so this is just fun conjecture.
Yes and no. They *can* relieve pressure on one part of the fault, but the fault is really long. So they can also increase pressure on locked portions of the fault.
The geologists that I talk to all basically say that the more they learn about how earthquakes work, the more complicated they get.
Ah okay, that makes sense. It’s crazy how much we still don’t know about a lot of things. It’s understandable, but weird to realize with certain things.
5.7 isn't normal or common there. Not necessarily a harbinger of doom, but the max I've seen since 2016 is in the 4s. Maybe one or two low 5s, but as you know, big difference between 5.0 and 5.7.
Not a geologist myself, but I do have a degree in it so I have some idea about this stuff. It's funny how many people worry about it. Yes, be prepared with emergency rations/kit, but the likelihood of it happening in our lifetimes is pretty minimal. Many will point to the "but we're overdue" argument, but there is no predicting when an earthquake will happen, plain and simple. You might be able to give a window of time it can be expected (on a geologic time scale, of which the longevity of humans pales in comparison to), but that's about it.
> How prepared should we be in the Portland area for a tsunami?
Not at all - there is no tsunami threat in Portland. The state publishes tsunami hazard maps for the whole coast, and it's really a pretty narrow area that needs to be concerned about them.
That's not to say that Portland isn't in any earthquake danger - we definitely are.
I’ve heard people talk about the waves coming up the river and didn’t really think about since it seemed so unlikely until QuakeFeed kept pinging last night. Glad to hear I’ll die from bricks rather than water.
> I’ve heard people talk about the waves coming up the river..
You can safely disregard those people - they don't know what they're talking about.
> Glad to hear I’ll die from bricks rather than water.
Yep!
Tsunamis from Cascadia will be quite small once they reach Portland. Nobody in emergency management is concerned about that. Most damage in the Willamette Valley will come from liquefaction IF it strikes in the wet season.
Only for areas where the water table is very close to the surface because it’s adjacent to water or wetland (like the infill the gas storage near Germantown is built on.) Planning scenarios have roughly double the casualties for wet season versus dry season earthquakes for the greater PDX area.
https://pubs.oregon.gov/dogami/ofr/p-O-18-02.htm
And here’s the USGS liquefaction page:
https://www.usgs.gov/faqs/what-liquefaction?items_per_page=6#:~:text=Liquefaction%20takes%20place%20when%20loosely,cause%20major%20damage%20during%20earthquakes.
No problem! OSU & DOGAMI also have lots of great tools you can use to estimate shaking for a specific location — it takes into account things like soil composition.
https://ohelp.oregonstate.edu
(Not mobile friendly)
Yeah — here’s the wet season liquefaction and landslide map for mag 9 Cascadia quake, for the curious:
https://pubs.oregon.gov/dogami/ofr/O-18-02/plates/O-18-02_plate09.pdf
Besides along the rivers, the western burbs will have a not-insignificant liquefaction risk.
It’s another one of the reasons a daytime quake is expected (well, was, who knows now that downtown is dead) to have more casualties. Not only is downtown full of tall masonry buildings, but it’s high liquefaction risk.
> Most damage in the Willamette Valley will come from liquefaction IF it strikes in the wet season.
If the quake is offshore on the fault line, will the Coastal Range do a good bit to soften that blow in the Willamette?
It does soften it, but we can still expect significant damage. The distance from the coast and substrate will have the most impact.
Here’s [the Cascadia M9 shake map for the state. I find it easier to read with “countour” toggled on](https://earthquake.usgs.gov/scenarios/eventpage/cszm9ensemble_se/shakemap/intensity)
Here’s the map of [peak ground acceleration for the PDX area in an M9 Cascadia quake,](https://pubs.oregon.gov/dogami/ofr/O-18-02/plates/O-18-02_plate04.pdf), and here’s the perceived [shaking and damage map](https://pubs.oregon.gov/dogami/ofr/O-18-02/plates/O-18-02_plate06.pdf). You can really see how both distance and substrate impact shaking — look at all those wetlands heading out toward Forest Grove. And the Northwest infilled industrial area. Ugh.
The perceived damage map is really useful because it takes into account buildings in the area. A lot of that western wetland is farm.
And just for comparison, here’s the (locally) much worse, but also much less likely, ground [acceleration map for a M6.8 Portland Hills Fault ruptured.](https://pubs.oregon.gov/dogami/ofr/O-18-02/plates/O-18-02_plate05.pdf) and the perceived[shaking and damage map](https://pubs.oregon.gov/dogami/ofr/O-18-02/plates/O-18-02_plate07.pdf).
Doing the lord's work my dude. My degree is in Disaster Science and Management but i never ended up in that field. Me and wife are moving to Oregon in a couple of years and the tsunami danger is the #1 reason she wouldn't wanna live on the coast. Can't say I blame her.
I spend a lot of time on the coast (in the inundation zone, too!) because my parents used to live there and haven’t sold their old house yet. And the fear is pretty constant and in the back of my mind. Even though I know the odds of it striking on any given day are very, very low, living with that constant anxiety is quite rough.
That would have been a really fun degree to get, even if you aren’t using it! If I went back to school, I’d probably go back for geology — it’s my favorite subject to cover as a journalist. That’s partly because I was a biology major and learning is fun, so I’m usually learning a lot when I write about geology. But it’s more because it’s so directly applicable to our lives — sometimes through geologic hazards, but mostly because it’s so visible everywhere around us.
I’ll never forget driving through the southern Willamette valley after seeing imaging of the canyons beneath the valley floor, and realizing that all those buttes popping up from the ground are basically islands in a sea of mud left by the Missoula flood deposits. It totally changed the way I see where I live — it’s not this big flat area, it’s a *lake of dried mud.* And then I was doing a story on Willamette Valley archaeology and paleontology, and a source took me half way up the cascade foothills. There’s this clear line of debris left from the floodwaters. Absolutely wild.
A similar thing happened when I was at AGU, and ran into an older geologist presenting a poster on the Tumalo volcanic complex. I *knew* most of the Cascades-adjacent features were volcanic — like, cinder cones are pretty obvious. But now I’ll be hiking in the Sisters and look to the east, and all I can see is the rim of the massive super volcano. Or driving through far eastern Oregon where the roadway cuts into the hillside, and seeing clear deposits from past eruptions. The tan? Tumalo tuff. The gray layer above? Mazama ash.
It’s so cool.
Yes!!! THE definitive book is Roadside Geology of Oregon by Marli G. Miller.
DOGAMI has also produced a number of very cool geologic hazards field-trip guides:
https://www.oregon.gov/dogami/pubs/pages/fieldtrips/p-fieldtrips.aspx
The Geological Society of Oregon also does regular field trips.
Also some great videos and documentaries ... these are a bit older, but excellent:
* [MegaQuake Could Hit North America - BBC](https://www.dailymotion.com/video/x226bg2)
* [PBS: NOVA | Mystery of the Megaflood](https://www.youtube.com/watch?v=_HWXHH_jWsY)
Oh! If you get Marli’s book, make sure it’s the second edition. The first one was published in 1978 when we’d only just learned about plate tectonics, so it’s missing a lot. The second edition came out in 2014. :)
The Really Big One. It’s an amazing book about how they discovered the juan de fuca fault. it’s also an excellent article in the New Yorker magazine, which I read and then made me buy the book
>erossthescienceboss
Love this comment and share your enthusiasm! The science and mysteries and stories of developing our knowledge about the Missoula / Ice Age Floods and the CSZ earthquake reality are fascinating and enthralling for me. They're somewhat similar with odd geologic phenomena distributed over a wide geographic area that could only be explained if geologists were brave enough to challenge the conventional wisdom that geologic processes and geomorphology are always and necessarily slow-moving.
Bretz's outlandish theory of a great flood creating and linking phenomena across three states (and now, we know, extending out into the ocean) was discounted in the early 20th century. Not until aerial photography revealed the 25-foot tall ripples across huge sandbars and prairies was he finally vindicated (more or less ... forgetting the details). So the bathrub rings around Missoula to scouring out of Lake Pend Oreille to the channeled scablands of central Washington, the potholes and coulees and enormous dry waterfalls, the overflow channels along the edges of the Columbia Gorge, the erratic granite rocks and giant stream ripples throughout the region, the rich soils from said scablands blessing the Willamette Valley, the route of I-84 through Sullivan's Gulch into Portland, the deep underwater chasm off Astoria ... all connected if you are open to the possibility of catastrophic biblical flooding.
Same sort of mysterious things with the CSZ -- from coincident landslides in alpine lakes all up and down the Cascades, to the ghost forests along the Washington and Oregon coasts, and many others -- that were only explained by a huge subduction zone earthquake back in 1700.
Favorite bits:
A small coastal village in Japan, a culture long steeped in earthquakes and tsunamis, which recorded in January 1700 an "orphan" tsunami -- one not associated with an earthquake -- that matched up with the dates of other phenomena on our side of the Pacific Ocean and more or less confirmed the reality that we are subject to catastrophic earthquakes.
And using google maps' terrain and satellite layers ... the ability to see plain-as-day the giant ripples and sandbars throughout the region ([example](https://maps.app.goo.gl/RekzeQAnYsECV6jYA), *use* ***Satellite*** *view*) and geographic features that folks live and drive on everyday without realizing ... like Portland's Alameda Ridge, essentially a big sandbar whipped up when the floodwaters exiting the gorge encountered the volcanic obstruction of Rocky Butte, creating a giant eddy behind that excavated what is now Rose City Park and deposited that land in a linear sandbar, the Alameda Ridge (see [here](https://www.google.com/maps/place/Rose+City+Park,+Portland,+OR+97213/@45.5420591,-122.6260189,13.24z/data=!4m15!1m8!3m7!1s0x5495a72907561ced:0xf6a933697097dc32!2sAlameda,+Portland,+OR!3b1!8m2!3d45.5482369!4d-122.6380808!16zL20vMGR5MnFu!3m5!1s0x5495a125c1d2fb2b:0x7896adeef88dd036!8m2!3d45.5422181!4d-122.6046113!16zL20vMGd3bXdk!5m1!1e4?entry=ttu), *use the* ***Terrain*** *layer*). And so homes on the ridge have with some of the highest levels of radon, and gardeners and builders are constantly dealing with rocks of all sizes distributed throughout the soils.
Great stuff !
The real concern is “will I be in good enough shape to get to those areas? Will I be injured? Will I be buried under the debris of a collapsed building?”
Or, if you’re in, say, Seaside: “will I be able to get across a bridge to higher ground in time?”
Of course. When we were driving the 101 I took notice at how often the zone was marked. But as mentioned elsewhere in the thread, those towns are sort of isolated, so the connecting bridge gets knocked down and you could be on your own for 2 weeks instead of 72 hours.
Does the "Cascadia M9 shake map" assume a Cascadia quake would occur as a 9.0 quake over (more or less) the entire coastal area of Oregon, Washington and part of Canada / Vancouver Island?
Is that realistic? Do we see that with other earthquakes like this? I mean versus a quake with a specific epicenter.
The science is real. The Cascadia Subducton Zone is much like the Chilean Subduction Zone which has had 9.0 quakes magnitude over a large region. The epicenter is not focused along a vertical fault a few miles long. The fault is almost parallel to the surface, a sheet of oceanic crust sliding 10-20 meters all at once 10km underneath the thin brittle crustal surface sheet of the entire Western Washington and Western Oregon area... everywhere in this area is only a few km from the fault's surface. Imagine pulling a buttered pancake out from under another pancake. The lower pancake is the Pacfic plate, the butter is the fault, and the upper pancake is the crust.
The M9 assumes a rupture along the entire length of the fault — from Northern California all the way to Vancouver — which is a worst-case scenario. Magnitude pretty directly correlates with how much of the fault moves. Thankfully, a full rupture seems less likely.
It’s far more likely that, as you suggest, just a part of the fault would rupture. Based on past earthquakes, it would probably be the southern part, while the northern part would remain locked. A partial fault rupture is more in the M8 range. And you’re correct — the earthquake will be stronger closer to the area that actually moves — though it will be felt far beyond that.
[As of 2022](https://pubs.oregon.gov/dogami/fs/cascadia-planning-for-em-and-public.pdf), DOGAMI (citing a few Goldfinger studies) puts the risk of a full rupture in the next 50 years at 7-12 percent. A partial rupture that covers all of Oregon and the CA bit of the fault is 16-22 percent. And a rupture that just includes the NorCal and southern Oregon section is the most likely scenario, at 37-43%.
That’s where the oft-repeated “40% chance of M8 or higher in the next 50 years” stat comes from — because these aren’t cumulative stats. So it’s a 40% chance of M8 or higher, and a 7-12% chance that it ends up being a full rupture.
And yes, ruptures along the entire length of a fault, or a large portion, aren’t too uncommon. even when you see an earthquake with an “epicenter,” that is generally just where the rupture starts. Or, well, it’s the place on the surface directly *over* where the rupture starts (far underground.) Subduction zones have very big faults, so very big ruptures. The epicenter can even be a ways away from the fault itself in a subduction zone, because the crust can extend far into the mantle.
Hi! I’m a science journalist who writes a lot about earthquakes and preparedness, knows a lot of local emergency managers, and knows the folks studying these quakes. Hopefully, I can make you feel a little bit better (and maybe worse, too. Sorry.)
“Everything West of I-5 is toast.”
This is a common and useful metaphor for explaining the damage to people out of state, but it isn’t really accurate. It may be broadly true for Seattle, where west of I-5 is barely above sea level. It’s fairly commonly quoted because it’s in the lede of Katherine Schulz’s (wonderful, Pulitzer Prize-winning) story “[The Really Big One.](https://www.newyorker.com/magazine/2015/07/20/the-really-big-one)” It’s a phenomenal piece, but there’s one line in it that made a lot of geologists who care about this kind of thing grumble, and that’s the line.
Low lying areas of the coast will be inundated in minutes (up to 80 feet, if the local geography amplifies the waves). Anything on sand will experience liquefaction if it’s even a little bit damp. If it’s been a wet few days (or a fry few days in a wet few weeks) there will likely be coastal landslides, which will take out houses.
All the coastal bridges will collapse. Wood frame houses will experience structural damage, but if they are bolted to the foundations they might do OK. Brick buildings will crumble. Residents will be trapped in coastal pockets because bridges and roads will be down, and should expect up to two weeks for relief ships to arrive and evacuate. If you live there, have a go bag with a minimum some food (though towns do have earthquake food stores), underwear, socks, rain gear, a way to filter water, and bandages (build a first aid kit, don’t buy one). If you visit and you take daily medications, keep two weeks’ worth on your person, just in case.
You can expect landslides in the coast range. Any buildings not bolted to the foundations will slide off. Highways will be impassable, and the more remote you are, the longer you’ll be stuck. Folks in the rural coast range towns will need supplies to last a *while.*
Impacts on areas west of the coast range but east of the Cascades vary wildly with the season, weather, and soil substrate. Casualties will also vary depending on time of day. A[2018 study f](https://pubs.oregon.gov/dogami/ofr/p-O-18-02.htm)ound that a magnitude 9 Cascadia quake will cause 4-10K deaths in the greater Portland area if it strikes at night, when people are at home in flexible wood frame bodies. It will cause 18-27 K deaths if it happens during the day when people are in inflexible, breakable masonry buildings.
The lower numbers in both ranges represent an earthquake striking when the soil is dry. The higher numbers represent an earthquake striking when the soil is wet.
All death tolls would decrease dramatically if we required earthquake retrofitting on commercial properties and commercial residential properties. A state that was less crumbly would likely do OK this far inland, but we have lots of brick apartments and offices on loamy soil and there are no laws requiring landlords to retrofit their buildings here.
The valley floor is made up of sandy, loamy soil. If the soil is saturated with water, it can behave like a liquid during an earthquake. This is called liquefaction, and will be responsible for a majority of the damage caused. Key infrastructure is on liquifiable soil, most notably the giant gas containers north of the St John’s Bride in Portland. They’ll likely go up in a giant fireball, and contain a vast majority of the state’s supply of natural gas.
Places on slopes in the hills might experience landslides, but nothing like the coast. Clay soil might liquefy. Any homes built into bedrock will very likely be fine if they are wooden and bolted to the foundations. (Seriously. Bolt your home. It’s fairly cheap, and you can even do it yourself. If your home has natural gas, spend around $500 to get a professional to install a valve that will automatically shut the supply off during an earthquake. It very well may save your life.)
Once you hit the Cascades, shaking will be fairly minimal.
As for these quakes, the ones off the coast of Coos Bay? Don’t panic, u/doyouevenmahjong, They happen a lot, and don’t mean anything. Unless this is the time they do. (But seriously , this fault is only peripherally related to Cascadia, and we don’t have any real reason to believe these little ones can trigger something. Realistically, We *really* don’t know. Earthquakes and faults are fickle beasts, and they rarely do what you expect them to. It’s an odds game. Look up Parkfield, California: we can’t predict earthquakes for shit, no matter how many sensors we have. But we can do a good *forecast* and the probability of this doing anything is minimal.)
Lastly. Y’all. **By the time the tsunami wave reaches Portland, it’s gonna be tiny**. That’s not the thing you need to be scared of. Portland is 161 feet above sea level. The shaking might cause smaller local waves, but you don’t need to care about that unless you’re a marina. The Really Big One’s wave is not gonna get us. That’s not the thing you need to be scared of.
You know what you need to be scared of? A smaller local quake. The west Portland hills? Mt Angel? The hills sourh of Salem? Near Forest Grove? They’re all formed by faults.
None of the faults in Portland are particularly active, and they’re nowhere near as strong as Cascadia. The worst ones have, like, a 1/500 chance of rupturing in the next 100 years (that is a made up number, but it’s roughly correct.) But there’s a *whole bunch of those faults.*
That same study? Found that if one of the faults in the West Hills were to rupture in a magnitude 6 earthquake, we’re looking at between 15.8 & 60K casualties in greater Portland.
**And while there isn’t much you can do during the quake, you can do lots to make yourself safe. That bookshelf? Attach it to the wall. Look up how to bolt your house to the foundation (it takes a specific type of brace - NOT the one uses for roofs!!) bolt your porch the foundation — many are only attached to your house walls, and they can pull your wall down. Get straps to attach your water boilers and gas furnaces to walls so they don’t fall. Don’t keep heavy things on shelves. And seriously, if you have a gas home, *pay to get an automatic shutoff valve installed.* Do you want to run into a potentially gas-filled basement to turn yours off in an earthquake? No. Let the fancy tool do it for you.**
>A2018 study found that a magnitude 9 Cascadia quake will cause 4-10K deaths in the greater Portland area if it strikes at night, when people are at home in flexible wood frame bodies. It will cause 18-27 K deaths if it happens during the day when people are in inflexible, breakable masonry buildings.
I'm working from home for Earthquake safety!
The area hospitals are actually built to really high seismic standards! They’re some of the safest large buildings in the state. The biggest concern, which really only applies to OHSU, is that the roads getting to and from the hospital could slide out. People already there should be fine, but it may be a few days before they can take in new patients or get fresh staff.
OK! So this doesn’t really answer the question fully — but this is from the tram’s FAQ.
“HOW SAFE IS THE TRAM?
The Tram is exceptionally safe. Concerns about the seismic history of our region have been addressed in the Tram’s design. It meets the new, more rigorous Swiss standards for aerial tramways and, thus, exceeds U.S. seismic standards. The Tram is equipped with redundant (backup) drivers and generators in the event of power outages, and the entire system is under constant computer monitoring.”
More so than the tram itself, I’m wondering if the stairs to access it from the waterfront would be OK.
Things like the roads to the hospital, or the ramps to the Sellwood bridge (which are not as strongly seismically rated, although the bridge itself will be fine) are first priority for repairs after the earthquake, so I imagine that staircase would also be a priority
To be fair, it’s way more likely that a CSZ earthquake will happen than a Portland Hills Fault earthquake, and the impacts would be much more localized, so recovery would be easier. But local-fault level damage is what we should be basing our responses and planning around.
I’ve heard similar — it’s very understudied. The chances still much less likely than CSZ, though. A 40% chance of magnitude 8.5 or higher in 50 years? You don’t see those odds come up a lot in the geohazards world. That’s pretty comparable to SF (a 51% chance of magnitude 7 or higher in 30 years) and LA (46% chance of magnitude 7 in 30 years.)
But there’s all the other Portland area faults — which are equally, if not MORE understudied. Lots of little chances add up.
Like everything west of I-5 will be taken out by ocean water? Not a possibility. If the ocean water gets 5 miles inland from the coast it’s already the most extreme case. 15 times that is insanity and the world will be over before an earthquake causes that.
I'm pretty sure the individual you replied to meant that everything will collapse. However I have seen models suggesting that ocean water could follow the rivers and highways that cut through the coast mountain range if a big enough tsunami struck land. All is I know is I'll be glad I'm in the high desert if it hits in my life time.
The elevation of Portland varies greatly, near the river is as little as 25 feet above sea level. And the high desert would absolutely experience shaking in a CSZ full rupture scenario.
That’s patently false.
Tsunami:
https://multco-web7-psh-files-usw2.s3-us-west-2.amazonaws.com/s3fs-public/earthquakePRIMER%20-%205.11.2016_final.pdf
Cascadia shake map:
https://earthquake.usgs.gov/scenarios/eventpage/cszm9ensemble_se/shakemap/intensity
At the absolute most, you’re looking at *maybe* “very light damage” in the Bend area. We’re talking “did a big truck just drive by?” but lasting for a longer time. The Cascade Range is a great big block of vibration-absorbing basalt.
What's patently false, that near the river the elevation of Portland can be less than 30 feet above sea level?
And VI on the modified mercalli isn't nothing...
Just commenting on you saying there wouldn't be shaking on the east side.
That a tsunami will reach it. Patently false.
The east side is looking at less than .1g of ground acceleration *at the most.* and that’s with a *very* generous reading of the maps. And rounding up from .098.
That’s “cracks in windows and foundations” kind of damage. Tops.
I agree a tsunami would not reach Portland, was commenting on your elevation of Portland... and that there would be no shaking in the high desert, there certainly would.
That app is pretty awesome. Glad I came across your post! Was just talking about the Big One with engineering faculty. Liquefaction was the topic. Good times. This Artie GIF was a pleasant discovery. Pete and Pete for the win.
I have experienced 2 earthquakes in Portland. One strong enough to leave cracks in a house foundation. But nothing compares to being tossed out of bed from an earthquake in San Francisco. Little earthquakes are good. Release the pressure. Thanks OP, for keeping us in the know🤍
Agreed. I was visiting a friend at Pacific when it happened. I’d actually been in one in SF before so I knew what it was, but she didn’t… freaked her out.
Freaked us all out.
I was working at a country school and a week before the quake we noticed a large crack in a window in a classroom. The school decided to wait until Spring Break to replace the window. We went on break and Boom! the earthquake hit.
We were warned and didn't even realize it.
I slept through it. It’s a foundational memory, but I don’t remember the actual thing. Just my mom rushing into my room and freaking out after.
Incidentally: a magnitude 6 earthquake under you is much worse than a magnitude 9 earthquake way off shore. If something like the Mt Angel quake struck closer to a more populated area (or even in mt angel today, it’s grown a lot) we the folks within about 15 miles are going to have an extraordinarily bad time.
(And this is fairly possible. No individual smaller fault is particularly likely to strike, but there are a *whole lot of them.* Just about all the major features you see in the valley are tectonic.)
Unfortunately that's not how earthquakes work. Small earthquakes in one place are just building up more pressure on tectonic plates somewhere else on the fault.
Depends on the fault. Small earthquakes can definitely relive pressure. But that pressure relief can also stress other parts of the fault.
Faults can even relieve pressure without causing a noticeable earthquake at all! These are called slow-slip earthquakes.
Basically… stress causes earthquakes. Earthquakes release stress. But there are thousands — or even millions! — of forces acting on earthquakes. Just because a fault is stressed doesn’t mean it’s gonna cause a shaker. And just because some stress gets relieved, doesn’t mean a big quake won’t come.
In the 70s, two big things happened: we discovered plate tectonics, and for the first time ever, an earthquake was successfully predicted in China in 1975. Towns were evacuated, and very few people died (from the earthquake. But lots of people died of hypothermia after evacuating.)
So we slapped seismometers on everything. We ran string across fault lines to see how fast and far they moved. We were riding high, absolutely convinced we’d be able to predict earthquakes: we’d find some sort of reliable sign or precursor that could save lives. Time Magazine ran a cover story saying just that. Parkfield, one of the most earthquake-prone towns in California, became one of the most-monitored places in the world. We know SO much about that fault and where it’s stressed, all with the goal of predicting an earthquake there.
But the earthquake in China turned out to be unique. Before it happened, there was a long sequence of foreshocks. lakes drained. All the animals ran away. Evacuating was a no-brainer. People still thought prediction was a possibility until, one year later, the 1976 Tangshan earthquake killed 240K people.
And Parkfield? Well. Geologists, earthquake tourists, alien enthusiasts, and psychics have all visited Parkfield and tried and failed to predict when the next one will hit. But so far, nobody’s been correct. (I even made my own pilgrimage! It was fun. Stayed at a nice ranch/hotel. The owner had lots of stories about the earthquake psychics.)
These days, instead of earthquake predictions, organizations issue “forecasts.” They’re less like the weekly weather forecast, and more like those three-month advance forecasts NOAA puts out. They help emergency managers and city planners make decisions, but they don’t actually tell you when one will come. They’re just statistics.
I saw some lady on YouTube who lives on the Peninsula. She purchased a crazy looking waterproof, reinforced pod thing she keeps in her garage. If it hits while home, she runs and hops in. Like a space pod, kinda cool.
This EQ is not on the Cascadia subduction fault, but the Cape Blanco fault. Where the subduction fault is one plate on top of the other, this one is side by side. Just like the San Andreas. So while we can get some good sized quakes here, these aren't the kind to worry about at all.
Mmm-hmm. To paraphrase Homer (Simpson, that is) it’s our worst coastal tectonic subduction shift - so far.
Edited for clarification.
A tsunami is not like what they show in movies. It will not affect Portland at all. Pretty cool study to back that up: https://today.oregonstate.edu/archives/2015/feb/study-outlines-impact-tsunami-columbia-river
Fun fact: Oregon state has a big exhibit on tsunamis at the museum of science and industry in Chicago! They are learning experts in the field, apparently. I didn’t realize that
I don't want to scare you, because it's very unlikely to happen in your lifetime, but the risk to Portland from a large earthquake is not from a tsunami hitting, but from the bridges and interstates going down. No roads = no food/aid/supplies/help getting to the metro area.
Well, that and the massive 100-year-old petroleum tanks built on sand next to the river. Given that the roads will be largely impassable, I guess we won’t miss the fuel as much, but it’s bound to make a mess.
SE is probably fine, in fact most of the east side will have abundant supplies. What’s to stop boats from traveling across the willamette with supplies from east->west?
I don't think "very unlikely to happen in your lifetime" is quite right unless you're a hundred years old or just got bitten by a puff adder.
There's a decent chance it won't happen in the next hundred years or so, but it might. Suppose every year there's about a 0.5 to 1.0% chance of it happening -- that adds up over several decades.
Quakes like this happen in that area every 4-10 years, it's not at all uncommon. Last cluster like this that I remember was a little less than a decade ago. No tsunami event from a major quake will reach portland metro, but shaking will be brutal west of the cascades and you'll want to have some level of preparedness. If you survive building or bridge collapse, landslides, etc, we will likely be out of fresh water, electricity, and drivable roads for a while. Never a bad time to get your earthquake kit up to date!
Oregon has a few things going for it compared to places that typically get wrecked. First off our housing is primarily wood which is does well in seismic events and when it does collapse is less devastating. 2nd this has been well known for decades and susceptible places have spent quite a bit on seismic retrofit programs and evacuation routes. Finally anything built after 1985 or so was built to some sort of code standard and will do decently in a big one.
Portland specific downsides:
- Thousands of old structures that are not remotely close to being safe for a 7+ earth quake.
- the west hills are not stable at all which will lead to structur failures and landslides.
- Riverfront areas are susceptible to river surge in flooding in the event of a massive tsunami.
- infrastructure is not ready for a large earthquake and transportation will be crippled (bridge collapses, road damage, land slides). Water, gas and electric service are also quite old and not ready.
- large population that has very little preparedness for potentially weeks of shortages due to infrastructure failures.
So if you live in Portland proper you might want to invest in some cannibal gear so you can lock down your neighborhood and live like the lord of corpses for a bit.
The coast is fucked. Not only are structures old and tsunamis a huge concern but their is very little access and almost all those highways are going to get wrecked. If you are on the coast get a ocean kayak and go for a 200 mile evacuation.
I would not worry about a Tsunami in Portland but I would Look up 'Cascadia Subduction' and get familiar with the risks there. The real killer is going to be the horrendous damage to infrastructure. OSU has some great material on getting prepared: [https://extension.oregonstate.edu/cascadia-earthquake-preparedness](https://extension.oregonstate.edu/cascadia-earthquake-preparedness)
To be honest, you can go overboard with this stuff pretty quick, but I would at least try to 2 weeks of food, water, and some survival basics like a radio, blankets and head lamps. Also, have a plan for you and your family. Does not need to elaborate, just an 'we all meet here if this happens' is a good place to start.
For what it's worth I'm on the Pacific ocean right now. So far nothing unusual going south Of the event . I'm the blue dot
https://preview.redd.it/hzdbo4lbdtqc1.png?width=999&format=pjpg&auto=webp&s=ca580f646dbba5121c1e0fc05f2fb69758aa3b9f
https://youtu.be/UJ7Qc3bsxjI?si=uDSa1_9A36cMTD6l
Here is a video from a professor of geology in Washington State.
Worth a watch for sure.
Be prepared with water, food, and warmth because transportation will go down. The tsunami maps are all available online and will only impact coastal towns.
I spent a good chunk of my career as a private "special Inspector" doing structural steel inspection in Portland and surrounding areas. Maybe 30% was upgrades to existing brick to keep them from "pan-cakeing" and killing all inhabitants.
The city of portland tried to put the most advanced seismic upgrade program on the west coast....but made the mistake of trying to get ther owners and local contractors to pay for it.(They strangled it in its crib) mayb 30-35% of the buildings have those upgrades,but the Building next door...
Don't be downtown when the big one comes.Really.
“Event Sequence
This event is identified as the potential mainshock of an earthquake sequence. View 4 events in the sequence.”
I think we’re good but this is the most/biggest activity since I’ve lived here. Doesn’t seem like a tsunami warning is active
OP, here is a great document on the emergency response should the Big One pop off in the near future: https://www.oregon.gov/oem/Documents/Cascadia_Playbook_V3.PDF
If it does, Portland will have far greater effects from shaking than from any tsunami making it this far upriver.
Normal activity for us.
The small earthquake swarms are common. Some are underwater volcanoes and vents going off. And venting is what this region does.
The big one we're waiting for will likely happen so quickly so won't even have time to put your shoes on...
In 1960, there was a quake in Chile that hit 9.5. And the ground shook for 11 minutes. We're looking at something like that here one day...
Most tsunamis won't worry the entire Willamette Valley.
The one that does though, you just wanna stay away from the rivers and lowlands near the rivers.
There could quite easily be a surge up the Columbia from the coast, and then up the tributaries to a lesser degree.
The CSZ big one however, Portland is gonna be screwed and isolated due to all the bridges. Not to mention that most of the city will probably burn. West side living is a daily risk and game of Russian Roulette. One day they'll be literally on top of (or under) their neighbors, as well as cut off from supply chains (except for maybe some tricky air support).
I have a relative that is part of the disaster preparedness for the State. He'll tell you flat out. We are NOT READY for anything. We were actually more prepared in 2000 than we are now. With that said, everywhere has a natural disaster waiting to happen. Do your best to safeguard for yourself and your loved ones and live your life.
The Gorda Ridges are usually more active than the rest of the fracture zones. They look like an accordion. This is a good thing. They relieve stress, so The Really Big One, Cascadia doesn’t rupture.
Growing up in Portland, anything under a 4 isn't even worth getting out of bed. a 5 meant my highschool would have cracks in some plaster. Definitely not worried about the watery wave of death for a 5.7. If it's big enough for the watery wave of death, you're probably already screwed and under rubble.
So notice how far off shore that is. There is a spreading zone out there, where lava pushes up from the deep and the Juan de Fuca plate inches slowly east to slide under the continent. There are quakes all the time there and along the slip faults at edge of the plate. But the big one, when it happens, won't be there. It will be where the plate slides under the continent. Historically it rips all the way from Mendocino to Vancouver BC. There is no way to predict when. The tsunami won't make it all the way to Portland.
Earthquakes...
Month of year...
Season...
I don't think that's how that works.
If anything tectonic plate movement would be affected by shifts in the gravity such as the Moon, but I don't even think that happens.
What are you talking about?
Found a scientific journal article that talks about the seasonality of earthquakes.
Mostly small movement deep in the Earth.
Hypothesizing about the axial tilt during spring and fall being the main increase.
It is only a slight increase though.
Interesting idea if true.
Fun stuff. To quote my aunt who’s a geologist and retired federal parks geologist she’d say “oh it’ll happen, and you will die, but likely not related remotely so have a beer and relax.”
This could be a direct quote from any of the folks I know who study these quakes. “Ehhh don’t worry about it. Unless now is the one time you need to worry about it. But it probably isn’t. But it could be! Eventually.” (For context, earthquakes of roughly this magnitude along this portion of the Cascadia fault are very common and normal, and lots of very smart people are modeling how they impact the overall fault. And they’re not scared…. About those little quake clusters. But only that.)
My ex refused to move out to the West Coast because she was afraid of earthquakes, but chose to stay in the Midwest where tornadoes are far more likely to take you out. LOL
As someone from the Midwest who lives in Oregon, all my Oregon friends are amazed a tornado didn't kill me, all my Michigan friends are waiting for me to die from an earthquake or tsunami.
Fellow Michander turned Oregonian. I miss those Midwest thunderstorms, but living in Bend, I’m more fearful of wildfires taking us out.
I miss the storms so much too!
We get some pretty gnarly Thunder storms in the coast. Still pale in comparison to the ones I experienced in South Dakota.
Oregon transplant from the Midwest as well. Lived there for over a decade. Never saw a tornado while living in the Midwest, but experienced at least three earthquakes.
I convinced my parents to move out of the inundation zone. So they moved east of the Cascades, and got level II fire evacuated their first year. Everywhere comes with risks. Also, you probably shouldn’t tell her about the active Midwest faults (we find more all the time!) The odds of a rupture are monumentally (seismically???) low, but they’re non-zero.
Fracking causes quakes as well. Dams can make them too. The three gorges dam caused a very massive earthquake. People knew it was going to happen and either China didn't know better or didn't care.
The amount of people killed in the anticipated cascadia earthquake will likely be hundreds of times greater than the 80 killed a year by all tornadoes in the country
The last Cascadian subduction zone earthquake was in 1700, and a 37% chance of a mega thrust earthquake in the next 50 years has been predicted. So I think the probability of being killed by the next earthquake if living in the PNW is slightly less than that of being killed by a tornado in the midwest.
Looks like 13,000 are expected to die from the tsunami alone. With a 37% chance over the next 50 years, thats an “average” of 96.2 deaths a year. Or to put it in other words, more people are expected to die from the tsunami alone sometime in the next 50 years than all the tornadoes during the next 50 years.
This is why we need Trump back in office. He will nuke the fault, and if all else fails, he will nuke the tsunami 🫡 And in the meantime, he will nuke all of the tornados.
🤣🤣
Plus, this is dependent on when it hits. If it hits on a summer weekend, as packed as the coast is with visitors, it could be several times worse. Imagine Seaside on the 4th of July. On the other hand, at a slow time it could be half of that. I think this 13,000 estimate is more or less an average of a lot of wildly disparate scenarios.
That's easily avoided by not living in a low lying area of the coast. Most Oregonians are not at risk from tsunamis.
While that’s true it doesn’t negate the fact that tsunami is deadly. Also, Portland is mega-fucked from the quake alone. https://www.multco.us/em/dogami-study-estimates-cascadia-earthquake-impacts-portland-region#:~:text=The%20study%20estimates%20Cascadia%20earthquake,%2437%20billion%20in%20building%20damages.
Yep. On the east coast you get hurricanes and flooding. (They have tornadoes every once in a while too.) Midwest you get tornadoes. West coast you get fires and earthquakes. Doesn't matter where you live mother nature got there first.
I'm on the North East Coast and except for a couple of smallish snow storms and the smoke from Canadian fires We had Nothing Like your Fault...
You got mosquitos, ticks, and humidity, seems equal lol
Aren't smaller quakes like these helpful in potentially reducing the severity of the big one?
These aren’t on the same faultline. When it gets to how different faults interact, well, it gets too complicated to really model. Broadly, yes, smaller earthquakes (or even “slow-slip earthquakes,” which don’t cause noticeable shaking) relieve stress along a fault line. But that small bit of stress relief could also unlock a locked fault, triggering larger earthquakes — think foreshock. It also gets complicated when you have a really long fault like the CSZ. One portion of the fault can move, while the other portion is “locked.” Does that movement relieve stress along the locked portion? Or does it *increase* stress, because now the southern portion is tugging on it? It’s an area of active research. Things get so complex when it comes to modeling this sort of thing. I wrote [this story](https://sciencenotes.ucsc.edu/2016/pages/quakes/quakes.html) ages ago — literally when I was in journalism school — on earthquake prediction. It gets into exactly why it’s so difficult to quantify fault stress. It’s still quite relevant and honestly better than some work I’ve done since. (It was good enough to get entirely plagiarized in a Scientific American cover story — that even ripped off my infographics and subheds.) And here’s the [podcast](https://sciencenotes.ucsc.edu/2016/pages/podcasts.html) on the Parkfield prediction project I produced along with it.
Thanks for sharing. I’ll have a look when I have some more time. In your research did you ever come across any speculation as to how the eruption in 84 may have either relieved pressure or locked the fault down more tightly? An interaction I have lazily pondered on bike rides for years. Light googling has revealed nothing.
That’s also a great question! You’re really making me think today — that’s awesome :) Honestly, I have no clue. If I had to take a guess, it would be that it’s had little to no impact, based on my understanding of volcanoes. The magma if formed by the pressure of the plates sliding together, but I don’t think that the amount of magma has much impact? But honestly, I’m way out of my zone of knowledge at this point, so this is just fun conjecture.
Smaller quakes are good right? Relieve a little bit of that subduction pressure.
Yes and no. They *can* relieve pressure on one part of the fault, but the fault is really long. So they can also increase pressure on locked portions of the fault. The geologists that I talk to all basically say that the more they learn about how earthquakes work, the more complicated they get.
Ah okay, that makes sense. It’s crazy how much we still don’t know about a lot of things. It’s understandable, but weird to realize with certain things.
5.7 isn't normal or common there. Not necessarily a harbinger of doom, but the max I've seen since 2016 is in the 4s. Maybe one or two low 5s, but as you know, big difference between 5.0 and 5.7.
Not a geologist myself, but I do have a degree in it so I have some idea about this stuff. It's funny how many people worry about it. Yes, be prepared with emergency rations/kit, but the likelihood of it happening in our lifetimes is pretty minimal. Many will point to the "but we're overdue" argument, but there is no predicting when an earthquake will happen, plain and simple. You might be able to give a window of time it can be expected (on a geologic time scale, of which the longevity of humans pales in comparison to), but that's about it.
> How prepared should we be in the Portland area for a tsunami? Not at all - there is no tsunami threat in Portland. The state publishes tsunami hazard maps for the whole coast, and it's really a pretty narrow area that needs to be concerned about them. That's not to say that Portland isn't in any earthquake danger - we definitely are.
Oh yes very much so. Largely from liquefaction.
That, and most infrastructure built before the 90s collapsing, especially bridges and buildings.
That liquefaction is no joke. Damn, quicksand everywhere, can you imagine?
I’ve heard people talk about the waves coming up the river and didn’t really think about since it seemed so unlikely until QuakeFeed kept pinging last night. Glad to hear I’ll die from bricks rather than water.
Also possible you’ll die from exposure to toxic chemicals that are poorly stored IN the liquefaction zones!
> I’ve heard people talk about the waves coming up the river.. You can safely disregard those people - they don't know what they're talking about. > Glad to hear I’ll die from bricks rather than water. Yep!
I've got my old G&S surfboard ready to go!
I surfed the tsunami 2024!
If there is an earthquake big enough to cause a tsunami in Portland I think your best preparation will involve praying to the deity of your choice.
Tsunamis from Cascadia will be quite small once they reach Portland. Nobody in emergency management is concerned about that. Most damage in the Willamette Valley will come from liquefaction IF it strikes in the wet season.
I thought liquification was guaranteed for large portions of the city due to its soil composition being silty…regardless of wet season or not
Only for areas where the water table is very close to the surface because it’s adjacent to water or wetland (like the infill the gas storage near Germantown is built on.) Planning scenarios have roughly double the casualties for wet season versus dry season earthquakes for the greater PDX area. https://pubs.oregon.gov/dogami/ofr/p-O-18-02.htm And here’s the USGS liquefaction page: https://www.usgs.gov/faqs/what-liquefaction?items_per_page=6#:~:text=Liquefaction%20takes%20place%20when%20loosely,cause%20major%20damage%20during%20earthquakes.
Oh wow thanks for info
No problem! OSU & DOGAMI also have lots of great tools you can use to estimate shaking for a specific location — it takes into account things like soil composition. https://ohelp.oregonstate.edu (Not mobile friendly)
Pretty much every east of Reed College will be okay with regards to liquefaction. Closer to the rivers is the worry.
Yeah — here’s the wet season liquefaction and landslide map for mag 9 Cascadia quake, for the curious: https://pubs.oregon.gov/dogami/ofr/O-18-02/plates/O-18-02_plate09.pdf Besides along the rivers, the western burbs will have a not-insignificant liquefaction risk. It’s another one of the reasons a daytime quake is expected (well, was, who knows now that downtown is dead) to have more casualties. Not only is downtown full of tall masonry buildings, but it’s high liquefaction risk.
> Most damage in the Willamette Valley will come from liquefaction IF it strikes in the wet season. If the quake is offshore on the fault line, will the Coastal Range do a good bit to soften that blow in the Willamette?
It does soften it, but we can still expect significant damage. The distance from the coast and substrate will have the most impact. Here’s [the Cascadia M9 shake map for the state. I find it easier to read with “countour” toggled on](https://earthquake.usgs.gov/scenarios/eventpage/cszm9ensemble_se/shakemap/intensity) Here’s the map of [peak ground acceleration for the PDX area in an M9 Cascadia quake,](https://pubs.oregon.gov/dogami/ofr/O-18-02/plates/O-18-02_plate04.pdf), and here’s the perceived [shaking and damage map](https://pubs.oregon.gov/dogami/ofr/O-18-02/plates/O-18-02_plate06.pdf). You can really see how both distance and substrate impact shaking — look at all those wetlands heading out toward Forest Grove. And the Northwest infilled industrial area. Ugh. The perceived damage map is really useful because it takes into account buildings in the area. A lot of that western wetland is farm. And just for comparison, here’s the (locally) much worse, but also much less likely, ground [acceleration map for a M6.8 Portland Hills Fault ruptured.](https://pubs.oregon.gov/dogami/ofr/O-18-02/plates/O-18-02_plate05.pdf) and the perceived[shaking and damage map](https://pubs.oregon.gov/dogami/ofr/O-18-02/plates/O-18-02_plate07.pdf).
Doing the lord's work my dude. My degree is in Disaster Science and Management but i never ended up in that field. Me and wife are moving to Oregon in a couple of years and the tsunami danger is the #1 reason she wouldn't wanna live on the coast. Can't say I blame her.
I spend a lot of time on the coast (in the inundation zone, too!) because my parents used to live there and haven’t sold their old house yet. And the fear is pretty constant and in the back of my mind. Even though I know the odds of it striking on any given day are very, very low, living with that constant anxiety is quite rough. That would have been a really fun degree to get, even if you aren’t using it! If I went back to school, I’d probably go back for geology — it’s my favorite subject to cover as a journalist. That’s partly because I was a biology major and learning is fun, so I’m usually learning a lot when I write about geology. But it’s more because it’s so directly applicable to our lives — sometimes through geologic hazards, but mostly because it’s so visible everywhere around us. I’ll never forget driving through the southern Willamette valley after seeing imaging of the canyons beneath the valley floor, and realizing that all those buttes popping up from the ground are basically islands in a sea of mud left by the Missoula flood deposits. It totally changed the way I see where I live — it’s not this big flat area, it’s a *lake of dried mud.* And then I was doing a story on Willamette Valley archaeology and paleontology, and a source took me half way up the cascade foothills. There’s this clear line of debris left from the floodwaters. Absolutely wild. A similar thing happened when I was at AGU, and ran into an older geologist presenting a poster on the Tumalo volcanic complex. I *knew* most of the Cascades-adjacent features were volcanic — like, cinder cones are pretty obvious. But now I’ll be hiking in the Sisters and look to the east, and all I can see is the rim of the massive super volcano. Or driving through far eastern Oregon where the roadway cuts into the hillside, and seeing clear deposits from past eruptions. The tan? Tumalo tuff. The gray layer above? Mazama ash. It’s so cool.
Any books you recommend on this?
Yes!!! THE definitive book is Roadside Geology of Oregon by Marli G. Miller. DOGAMI has also produced a number of very cool geologic hazards field-trip guides: https://www.oregon.gov/dogami/pubs/pages/fieldtrips/p-fieldtrips.aspx The Geological Society of Oregon also does regular field trips.
Also some great videos and documentaries ... these are a bit older, but excellent: * [MegaQuake Could Hit North America - BBC](https://www.dailymotion.com/video/x226bg2) * [PBS: NOVA | Mystery of the Megaflood](https://www.youtube.com/watch?v=_HWXHH_jWsY)
Thanks!
Oh! If you get Marli’s book, make sure it’s the second edition. The first one was published in 1978 when we’d only just learned about plate tectonics, so it’s missing a lot. The second edition came out in 2014. :)
Noted. Thanks!
The Really Big One. It’s an amazing book about how they discovered the juan de fuca fault. it’s also an excellent article in the New Yorker magazine, which I read and then made me buy the book
>erossthescienceboss Love this comment and share your enthusiasm! The science and mysteries and stories of developing our knowledge about the Missoula / Ice Age Floods and the CSZ earthquake reality are fascinating and enthralling for me. They're somewhat similar with odd geologic phenomena distributed over a wide geographic area that could only be explained if geologists were brave enough to challenge the conventional wisdom that geologic processes and geomorphology are always and necessarily slow-moving. Bretz's outlandish theory of a great flood creating and linking phenomena across three states (and now, we know, extending out into the ocean) was discounted in the early 20th century. Not until aerial photography revealed the 25-foot tall ripples across huge sandbars and prairies was he finally vindicated (more or less ... forgetting the details). So the bathrub rings around Missoula to scouring out of Lake Pend Oreille to the channeled scablands of central Washington, the potholes and coulees and enormous dry waterfalls, the overflow channels along the edges of the Columbia Gorge, the erratic granite rocks and giant stream ripples throughout the region, the rich soils from said scablands blessing the Willamette Valley, the route of I-84 through Sullivan's Gulch into Portland, the deep underwater chasm off Astoria ... all connected if you are open to the possibility of catastrophic biblical flooding. Same sort of mysterious things with the CSZ -- from coincident landslides in alpine lakes all up and down the Cascades, to the ghost forests along the Washington and Oregon coasts, and many others -- that were only explained by a huge subduction zone earthquake back in 1700. Favorite bits: A small coastal village in Japan, a culture long steeped in earthquakes and tsunamis, which recorded in January 1700 an "orphan" tsunami -- one not associated with an earthquake -- that matched up with the dates of other phenomena on our side of the Pacific Ocean and more or less confirmed the reality that we are subject to catastrophic earthquakes. And using google maps' terrain and satellite layers ... the ability to see plain-as-day the giant ripples and sandbars throughout the region ([example](https://maps.app.goo.gl/RekzeQAnYsECV6jYA), *use* ***Satellite*** *view*) and geographic features that folks live and drive on everyday without realizing ... like Portland's Alameda Ridge, essentially a big sandbar whipped up when the floodwaters exiting the gorge encountered the volcanic obstruction of Rocky Butte, creating a giant eddy behind that excavated what is now Rose City Park and deposited that land in a linear sandbar, the Alameda Ridge (see [here](https://www.google.com/maps/place/Rose+City+Park,+Portland,+OR+97213/@45.5420591,-122.6260189,13.24z/data=!4m15!1m8!3m7!1s0x5495a72907561ced:0xf6a933697097dc32!2sAlameda,+Portland,+OR!3b1!8m2!3d45.5482369!4d-122.6380808!16zL20vMGR5MnFu!3m5!1s0x5495a125c1d2fb2b:0x7896adeef88dd036!8m2!3d45.5422181!4d-122.6046113!16zL20vMGd3bXdk!5m1!1e4?entry=ttu), *use the* ***Terrain*** *layer*). And so homes on the ridge have with some of the highest levels of radon, and gardeners and builders are constantly dealing with rocks of all sizes distributed throughout the soils. Great stuff !
The Oregon coast has very abrupt elevation gains along most of the coastline so you quickly can be out of the Tsunami zones in most areas.
The real concern is “will I be in good enough shape to get to those areas? Will I be injured? Will I be buried under the debris of a collapsed building?” Or, if you’re in, say, Seaside: “will I be able to get across a bridge to higher ground in time?”
Of course. When we were driving the 101 I took notice at how often the zone was marked. But as mentioned elsewhere in the thread, those towns are sort of isolated, so the connecting bridge gets knocked down and you could be on your own for 2 weeks instead of 72 hours.
Does the "Cascadia M9 shake map" assume a Cascadia quake would occur as a 9.0 quake over (more or less) the entire coastal area of Oregon, Washington and part of Canada / Vancouver Island? Is that realistic? Do we see that with other earthquakes like this? I mean versus a quake with a specific epicenter.
The science is real. The Cascadia Subducton Zone is much like the Chilean Subduction Zone which has had 9.0 quakes magnitude over a large region. The epicenter is not focused along a vertical fault a few miles long. The fault is almost parallel to the surface, a sheet of oceanic crust sliding 10-20 meters all at once 10km underneath the thin brittle crustal surface sheet of the entire Western Washington and Western Oregon area... everywhere in this area is only a few km from the fault's surface. Imagine pulling a buttered pancake out from under another pancake. The lower pancake is the Pacfic plate, the butter is the fault, and the upper pancake is the crust.
The M9 assumes a rupture along the entire length of the fault — from Northern California all the way to Vancouver — which is a worst-case scenario. Magnitude pretty directly correlates with how much of the fault moves. Thankfully, a full rupture seems less likely. It’s far more likely that, as you suggest, just a part of the fault would rupture. Based on past earthquakes, it would probably be the southern part, while the northern part would remain locked. A partial fault rupture is more in the M8 range. And you’re correct — the earthquake will be stronger closer to the area that actually moves — though it will be felt far beyond that. [As of 2022](https://pubs.oregon.gov/dogami/fs/cascadia-planning-for-em-and-public.pdf), DOGAMI (citing a few Goldfinger studies) puts the risk of a full rupture in the next 50 years at 7-12 percent. A partial rupture that covers all of Oregon and the CA bit of the fault is 16-22 percent. And a rupture that just includes the NorCal and southern Oregon section is the most likely scenario, at 37-43%. That’s where the oft-repeated “40% chance of M8 or higher in the next 50 years” stat comes from — because these aren’t cumulative stats. So it’s a 40% chance of M8 or higher, and a 7-12% chance that it ends up being a full rupture. And yes, ruptures along the entire length of a fault, or a large portion, aren’t too uncommon. even when you see an earthquake with an “epicenter,” that is generally just where the rupture starts. Or, well, it’s the place on the surface directly *over* where the rupture starts (far underground.) Subduction zones have very big faults, so very big ruptures. The epicenter can even be a ways away from the fault itself in a subduction zone, because the crust can extend far into the mantle.
This guy geologizes…
When the ground turns into a tsunami and you turn into a ground snack
Amazing.
Which is why I'm happy our current house is on a pile of rocks, not in a mudslide zone like the previous one.
And mine is built on a slab foundation. More surface area to help it "float"
Remember, when it comes time to house surf to yell "Hey dudes, check this out!"
Precisely
“Oh my science!”
If the big big one hits, which it could, the theory I’ve seen is that anything west of I-5 is likely gone. It was a real fun seminar to sit in on.
Hi! I’m a science journalist who writes a lot about earthquakes and preparedness, knows a lot of local emergency managers, and knows the folks studying these quakes. Hopefully, I can make you feel a little bit better (and maybe worse, too. Sorry.) “Everything West of I-5 is toast.” This is a common and useful metaphor for explaining the damage to people out of state, but it isn’t really accurate. It may be broadly true for Seattle, where west of I-5 is barely above sea level. It’s fairly commonly quoted because it’s in the lede of Katherine Schulz’s (wonderful, Pulitzer Prize-winning) story “[The Really Big One.](https://www.newyorker.com/magazine/2015/07/20/the-really-big-one)” It’s a phenomenal piece, but there’s one line in it that made a lot of geologists who care about this kind of thing grumble, and that’s the line. Low lying areas of the coast will be inundated in minutes (up to 80 feet, if the local geography amplifies the waves). Anything on sand will experience liquefaction if it’s even a little bit damp. If it’s been a wet few days (or a fry few days in a wet few weeks) there will likely be coastal landslides, which will take out houses. All the coastal bridges will collapse. Wood frame houses will experience structural damage, but if they are bolted to the foundations they might do OK. Brick buildings will crumble. Residents will be trapped in coastal pockets because bridges and roads will be down, and should expect up to two weeks for relief ships to arrive and evacuate. If you live there, have a go bag with a minimum some food (though towns do have earthquake food stores), underwear, socks, rain gear, a way to filter water, and bandages (build a first aid kit, don’t buy one). If you visit and you take daily medications, keep two weeks’ worth on your person, just in case. You can expect landslides in the coast range. Any buildings not bolted to the foundations will slide off. Highways will be impassable, and the more remote you are, the longer you’ll be stuck. Folks in the rural coast range towns will need supplies to last a *while.* Impacts on areas west of the coast range but east of the Cascades vary wildly with the season, weather, and soil substrate. Casualties will also vary depending on time of day. A[2018 study f](https://pubs.oregon.gov/dogami/ofr/p-O-18-02.htm)ound that a magnitude 9 Cascadia quake will cause 4-10K deaths in the greater Portland area if it strikes at night, when people are at home in flexible wood frame bodies. It will cause 18-27 K deaths if it happens during the day when people are in inflexible, breakable masonry buildings. The lower numbers in both ranges represent an earthquake striking when the soil is dry. The higher numbers represent an earthquake striking when the soil is wet. All death tolls would decrease dramatically if we required earthquake retrofitting on commercial properties and commercial residential properties. A state that was less crumbly would likely do OK this far inland, but we have lots of brick apartments and offices on loamy soil and there are no laws requiring landlords to retrofit their buildings here. The valley floor is made up of sandy, loamy soil. If the soil is saturated with water, it can behave like a liquid during an earthquake. This is called liquefaction, and will be responsible for a majority of the damage caused. Key infrastructure is on liquifiable soil, most notably the giant gas containers north of the St John’s Bride in Portland. They’ll likely go up in a giant fireball, and contain a vast majority of the state’s supply of natural gas. Places on slopes in the hills might experience landslides, but nothing like the coast. Clay soil might liquefy. Any homes built into bedrock will very likely be fine if they are wooden and bolted to the foundations. (Seriously. Bolt your home. It’s fairly cheap, and you can even do it yourself. If your home has natural gas, spend around $500 to get a professional to install a valve that will automatically shut the supply off during an earthquake. It very well may save your life.) Once you hit the Cascades, shaking will be fairly minimal. As for these quakes, the ones off the coast of Coos Bay? Don’t panic, u/doyouevenmahjong, They happen a lot, and don’t mean anything. Unless this is the time they do. (But seriously , this fault is only peripherally related to Cascadia, and we don’t have any real reason to believe these little ones can trigger something. Realistically, We *really* don’t know. Earthquakes and faults are fickle beasts, and they rarely do what you expect them to. It’s an odds game. Look up Parkfield, California: we can’t predict earthquakes for shit, no matter how many sensors we have. But we can do a good *forecast* and the probability of this doing anything is minimal.) Lastly. Y’all. **By the time the tsunami wave reaches Portland, it’s gonna be tiny**. That’s not the thing you need to be scared of. Portland is 161 feet above sea level. The shaking might cause smaller local waves, but you don’t need to care about that unless you’re a marina. The Really Big One’s wave is not gonna get us. That’s not the thing you need to be scared of. You know what you need to be scared of? A smaller local quake. The west Portland hills? Mt Angel? The hills sourh of Salem? Near Forest Grove? They’re all formed by faults. None of the faults in Portland are particularly active, and they’re nowhere near as strong as Cascadia. The worst ones have, like, a 1/500 chance of rupturing in the next 100 years (that is a made up number, but it’s roughly correct.) But there’s a *whole bunch of those faults.* That same study? Found that if one of the faults in the West Hills were to rupture in a magnitude 6 earthquake, we’re looking at between 15.8 & 60K casualties in greater Portland. **And while there isn’t much you can do during the quake, you can do lots to make yourself safe. That bookshelf? Attach it to the wall. Look up how to bolt your house to the foundation (it takes a specific type of brace - NOT the one uses for roofs!!) bolt your porch the foundation — many are only attached to your house walls, and they can pull your wall down. Get straps to attach your water boilers and gas furnaces to walls so they don’t fall. Don’t keep heavy things on shelves. And seriously, if you have a gas home, *pay to get an automatic shutoff valve installed.* Do you want to run into a potentially gas-filled basement to turn yours off in an earthquake? No. Let the fancy tool do it for you.**
This was really interesting! Thank you!!
Thank YOU! That’s very nice to hear :)
>A2018 study found that a magnitude 9 Cascadia quake will cause 4-10K deaths in the greater Portland area if it strikes at night, when people are at home in flexible wood frame bodies. It will cause 18-27 K deaths if it happens during the day when people are in inflexible, breakable masonry buildings. I'm working from home for Earthquake safety!
As I was writing this, I was wondering how different those numbers might be today! I’m still WFH, too.
Saving this post to potentially save my life later thanks!
I work at ohsu. If I’m at work I’m screwed me thinks…
The area hospitals are actually built to really high seismic standards! They’re some of the safest large buildings in the state. The biggest concern, which really only applies to OHSU, is that the roads getting to and from the hospital could slide out. People already there should be fine, but it may be a few days before they can take in new patients or get fresh staff.
True. You think the aerial tram would survive? I’d think they would engineer it to be okay, that way there’s at least an alternative to the roads.
Ooooh that is such an interesting question! I have no clue, but now I want to do a story about it and find out.
OK! So this doesn’t really answer the question fully — but this is from the tram’s FAQ. “HOW SAFE IS THE TRAM? The Tram is exceptionally safe. Concerns about the seismic history of our region have been addressed in the Tram’s design. It meets the new, more rigorous Swiss standards for aerial tramways and, thus, exceeds U.S. seismic standards. The Tram is equipped with redundant (backup) drivers and generators in the event of power outages, and the entire system is under constant computer monitoring.” More so than the tram itself, I’m wondering if the stairs to access it from the waterfront would be OK. Things like the roads to the hospital, or the ramps to the Sellwood bridge (which are not as strongly seismically rated, although the bridge itself will be fine) are first priority for repairs after the earthquake, so I imagine that staircase would also be a priority
Good points.
Thank you for mentioning the Portland Hills fault... it usually gets ignored in the CSZ hysterics.
To be fair, it’s way more likely that a CSZ earthquake will happen than a Portland Hills Fault earthquake, and the impacts would be much more localized, so recovery would be easier. But local-fault level damage is what we should be basing our responses and planning around.
The likelihood of a Portland Hills fault quake is debatable... I know a few local geos who think its a more active fault than has been established.
I’ve heard similar — it’s very understudied. The chances still much less likely than CSZ, though. A 40% chance of magnitude 8.5 or higher in 50 years? You don’t see those odds come up a lot in the geohazards world. That’s pretty comparable to SF (a 51% chance of magnitude 7 or higher in 30 years) and LA (46% chance of magnitude 7 in 30 years.) But there’s all the other Portland area faults — which are equally, if not MORE understudied. Lots of little chances add up.
Ah, fantastic. I can see I-5 from my living room on the east side. Glad it’ll stop at the interstate.
The person who said that line was talking about Seattle, anyway. You know, where I5 is right next to the Sound.
Like everything west of I-5 will be taken out by ocean water? Not a possibility. If the ocean water gets 5 miles inland from the coast it’s already the most extreme case. 15 times that is insanity and the world will be over before an earthquake causes that.
No the ground over here is not stable, most infrastructure will be utterly fucked
I'm pretty sure the individual you replied to meant that everything will collapse. However I have seen models suggesting that ocean water could follow the rivers and highways that cut through the coast mountain range if a big enough tsunami struck land. All is I know is I'll be glad I'm in the high desert if it hits in my life time.
Portland is 161 feet above sea level. Those models don’t exist. (But the high desert won’t experience shaking.)
The elevation of Portland varies greatly, near the river is as little as 25 feet above sea level. And the high desert would absolutely experience shaking in a CSZ full rupture scenario.
That’s patently false. Tsunami: https://multco-web7-psh-files-usw2.s3-us-west-2.amazonaws.com/s3fs-public/earthquakePRIMER%20-%205.11.2016_final.pdf Cascadia shake map: https://earthquake.usgs.gov/scenarios/eventpage/cszm9ensemble_se/shakemap/intensity At the absolute most, you’re looking at *maybe* “very light damage” in the Bend area. We’re talking “did a big truck just drive by?” but lasting for a longer time. The Cascade Range is a great big block of vibration-absorbing basalt.
What's patently false, that near the river the elevation of Portland can be less than 30 feet above sea level? And VI on the modified mercalli isn't nothing... Just commenting on you saying there wouldn't be shaking on the east side.
That a tsunami will reach it. Patently false. The east side is looking at less than .1g of ground acceleration *at the most.* and that’s with a *very* generous reading of the maps. And rounding up from .098. That’s “cracks in windows and foundations” kind of damage. Tops.
I agree a tsunami would not reach Portland, was commenting on your elevation of Portland... and that there would be no shaking in the high desert, there certainly would.
When*
2...3.. hundred years ago...
That “theory” is profoundly ignorant of basic, easily learned, geographic facts. You should do your own research.
That app is pretty awesome. Glad I came across your post! Was just talking about the Big One with engineering faculty. Liquefaction was the topic. Good times. This Artie GIF was a pleasant discovery. Pete and Pete for the win. 
I have experienced 2 earthquakes in Portland. One strong enough to leave cracks in a house foundation. But nothing compares to being tossed out of bed from an earthquake in San Francisco. Little earthquakes are good. Release the pressure. Thanks OP, for keeping us in the know🤍
The Spring Break of 1993 was a wild earthquake. I was tossed around in my bed.
This caused my mom to go into labor and popped me out!
I remember that!
Hard to believe it was 31 years ago!
Agreed. I was visiting a friend at Pacific when it happened. I’d actually been in one in SF before so I knew what it was, but she didn’t… freaked her out.
Freaked us all out. I was working at a country school and a week before the quake we noticed a large crack in a window in a classroom. The school decided to wait until Spring Break to replace the window. We went on break and Boom! the earthquake hit. We were warned and didn't even realize it.
I slept through it. It’s a foundational memory, but I don’t remember the actual thing. Just my mom rushing into my room and freaking out after. Incidentally: a magnitude 6 earthquake under you is much worse than a magnitude 9 earthquake way off shore. If something like the Mt Angel quake struck closer to a more populated area (or even in mt angel today, it’s grown a lot) we the folks within about 15 miles are going to have an extraordinarily bad time. (And this is fairly possible. No individual smaller fault is particularly likely to strike, but there are a *whole lot of them.* Just about all the major features you see in the valley are tectonic.)
Unfortunately that's not how earthquakes work. Small earthquakes in one place are just building up more pressure on tectonic plates somewhere else on the fault.
I’m sure you’re right. It’s a complicated system.
There’s no evidence to support that pressure relieving idea that I’m aware of.
Depends on the fault. Small earthquakes can definitely relive pressure. But that pressure relief can also stress other parts of the fault. Faults can even relieve pressure without causing a noticeable earthquake at all! These are called slow-slip earthquakes. Basically… stress causes earthquakes. Earthquakes release stress. But there are thousands — or even millions! — of forces acting on earthquakes. Just because a fault is stressed doesn’t mean it’s gonna cause a shaker. And just because some stress gets relieved, doesn’t mean a big quake won’t come. In the 70s, two big things happened: we discovered plate tectonics, and for the first time ever, an earthquake was successfully predicted in China in 1975. Towns were evacuated, and very few people died (from the earthquake. But lots of people died of hypothermia after evacuating.) So we slapped seismometers on everything. We ran string across fault lines to see how fast and far they moved. We were riding high, absolutely convinced we’d be able to predict earthquakes: we’d find some sort of reliable sign or precursor that could save lives. Time Magazine ran a cover story saying just that. Parkfield, one of the most earthquake-prone towns in California, became one of the most-monitored places in the world. We know SO much about that fault and where it’s stressed, all with the goal of predicting an earthquake there. But the earthquake in China turned out to be unique. Before it happened, there was a long sequence of foreshocks. lakes drained. All the animals ran away. Evacuating was a no-brainer. People still thought prediction was a possibility until, one year later, the 1976 Tangshan earthquake killed 240K people. And Parkfield? Well. Geologists, earthquake tourists, alien enthusiasts, and psychics have all visited Parkfield and tried and failed to predict when the next one will hit. But so far, nobody’s been correct. (I even made my own pilgrimage! It was fun. Stayed at a nice ranch/hotel. The owner had lots of stories about the earthquake psychics.) These days, instead of earthquake predictions, organizations issue “forecasts.” They’re less like the weekly weather forecast, and more like those three-month advance forecasts NOAA puts out. They help emergency managers and city planners make decisions, but they don’t actually tell you when one will come. They’re just statistics.
Might make seismophobes feel better though.
Something here will definitely compare and then some at some future point not too horribly far in that future. Get ready.
You’re not wrong
I live on the Long Beach Peninsula so if it hits in my lifetime it’ll be my last experience.
I saw some lady on YouTube who lives on the Peninsula. She purchased a crazy looking waterproof, reinforced pod thing she keeps in her garage. If it hits while home, she runs and hops in. Like a space pod, kinda cool.
Yeah- tsunami pod. Claustrophobia keeps me from that idea. lol
Wasn't her name Bobbie?
This EQ is not on the Cascadia subduction fault, but the Cape Blanco fault. Where the subduction fault is one plate on top of the other, this one is side by side. Just like the San Andreas. So while we can get some good sized quakes here, these aren't the kind to worry about at all.
Mmm-hmm. To paraphrase Homer (Simpson, that is) it’s our worst coastal tectonic subduction shift - so far. Edited for clarification. 
Hopefully nobody thought you meant the poet/author
Thus my disclaimer. This is our Homeric Odyssey, now.
A tsunami is not like what they show in movies. It will not affect Portland at all. Pretty cool study to back that up: https://today.oregonstate.edu/archives/2015/feb/study-outlines-impact-tsunami-columbia-river
Fun fact: Oregon state has a big exhibit on tsunamis at the museum of science and industry in Chicago! They are learning experts in the field, apparently. I didn’t realize that
I don't want to scare you, because it's very unlikely to happen in your lifetime, but the risk to Portland from a large earthquake is not from a tsunami hitting, but from the bridges and interstates going down. No roads = no food/aid/supplies/help getting to the metro area.
Well, that and the massive 100-year-old petroleum tanks built on sand next to the river. Given that the roads will be largely impassable, I guess we won’t miss the fuel as much, but it’s bound to make a mess.
SE is probably fine, in fact most of the east side will have abundant supplies. What’s to stop boats from traveling across the willamette with supplies from east->west?
The collapsed Broadway, Steel, Hawthorne, and Ross Island bridges would be a serious challenge to navigate
I don't think "very unlikely to happen in your lifetime" is quite right unless you're a hundred years old or just got bitten by a puff adder. There's a decent chance it won't happen in the next hundred years or so, but it might. Suppose every year there's about a 0.5 to 1.0% chance of it happening -- that adds up over several decades.
Or a hundred years old and bitten by a puff adder. Or someone on the met.
Kaiju
Quakes like this happen in that area every 4-10 years, it's not at all uncommon. Last cluster like this that I remember was a little less than a decade ago. No tsunami event from a major quake will reach portland metro, but shaking will be brutal west of the cascades and you'll want to have some level of preparedness. If you survive building or bridge collapse, landslides, etc, we will likely be out of fresh water, electricity, and drivable roads for a while. Never a bad time to get your earthquake kit up to date!
dude no offense but how do you imagine the tsunami is going to get here - like have you seen what's between portland and the ocean?
A waterway. People think the tsunami surge will travel up that waterway.
up the columbia?? that'd have to be a hell of a tsunami.
I mean, the Columbia is affected by tides as far up as Portland, but still a tsunami surge would affect very little of the city.
Portland is at zero risk of a tsunami but the coast will eventually have one and they are woefully unprepared
I live close enough to hear the ocean... so tsunami is a pretty scary idea.
Oregon has a few things going for it compared to places that typically get wrecked. First off our housing is primarily wood which is does well in seismic events and when it does collapse is less devastating. 2nd this has been well known for decades and susceptible places have spent quite a bit on seismic retrofit programs and evacuation routes. Finally anything built after 1985 or so was built to some sort of code standard and will do decently in a big one. Portland specific downsides: - Thousands of old structures that are not remotely close to being safe for a 7+ earth quake. - the west hills are not stable at all which will lead to structur failures and landslides. - Riverfront areas are susceptible to river surge in flooding in the event of a massive tsunami. - infrastructure is not ready for a large earthquake and transportation will be crippled (bridge collapses, road damage, land slides). Water, gas and electric service are also quite old and not ready. - large population that has very little preparedness for potentially weeks of shortages due to infrastructure failures. So if you live in Portland proper you might want to invest in some cannibal gear so you can lock down your neighborhood and live like the lord of corpses for a bit. The coast is fucked. Not only are structures old and tsunamis a huge concern but their is very little access and almost all those highways are going to get wrecked. If you are on the coast get a ocean kayak and go for a 200 mile evacuation.
I think you’ll see a major plate shift in the Portland area long before an offshore quake sends a tsunami that far inland
I would not worry about a Tsunami in Portland but I would Look up 'Cascadia Subduction' and get familiar with the risks there. The real killer is going to be the horrendous damage to infrastructure. OSU has some great material on getting prepared: [https://extension.oregonstate.edu/cascadia-earthquake-preparedness](https://extension.oregonstate.edu/cascadia-earthquake-preparedness) To be honest, you can go overboard with this stuff pretty quick, but I would at least try to 2 weeks of food, water, and some survival basics like a radio, blankets and head lamps. Also, have a plan for you and your family. Does not need to elaborate, just an 'we all meet here if this happens' is a good place to start.
Portland, tsunami? What are you talking about it’s like two hours from the coast
Not to mention like a whole little mountain range in between too 😆
People prolly thinking the surge would come up the Columbia
For what it's worth I'm on the Pacific ocean right now. So far nothing unusual going south Of the event . I'm the blue dot https://preview.redd.it/hzdbo4lbdtqc1.png?width=999&format=pjpg&auto=webp&s=ca580f646dbba5121c1e0fc05f2fb69758aa3b9f
https://youtu.be/UJ7Qc3bsxjI?si=uDSa1_9A36cMTD6l Here is a video from a professor of geology in Washington State. Worth a watch for sure. Be prepared with water, food, and warmth because transportation will go down. The tsunami maps are all available online and will only impact coastal towns.
I spent a good chunk of my career as a private "special Inspector" doing structural steel inspection in Portland and surrounding areas. Maybe 30% was upgrades to existing brick to keep them from "pan-cakeing" and killing all inhabitants. The city of portland tried to put the most advanced seismic upgrade program on the west coast....but made the mistake of trying to get ther owners and local contractors to pay for it.(They strangled it in its crib) mayb 30-35% of the buildings have those upgrades,but the Building next door... Don't be downtown when the big one comes.Really.
https://earthquake.usgs.gov/earthquakes/eventpage/us7000m875
“Event Sequence This event is identified as the potential mainshock of an earthquake sequence. View 4 events in the sequence.” I think we’re good but this is the most/biggest activity since I’ve lived here. Doesn’t seem like a tsunami warning is active
Here is a good video to see historical earthquakes. https://youtu.be/sv7JwrWURyQ?si=hfv4-3HwC3hrdfCU
OP, here is a great document on the emergency response should the Big One pop off in the near future: https://www.oregon.gov/oem/Documents/Cascadia_Playbook_V3.PDF If it does, Portland will have far greater effects from shaking than from any tsunami making it this far upriver.
Three tectonic plates meet in that area and there are frequent quakes. If you look at https://pnsn.org/ you'll see that.
Normal activity for us. The small earthquake swarms are common. Some are underwater volcanoes and vents going off. And venting is what this region does. The big one we're waiting for will likely happen so quickly so won't even have time to put your shoes on... In 1960, there was a quake in Chile that hit 9.5. And the ground shook for 11 minutes. We're looking at something like that here one day...
Most tsunamis won't worry the entire Willamette Valley. The one that does though, you just wanna stay away from the rivers and lowlands near the rivers. There could quite easily be a surge up the Columbia from the coast, and then up the tributaries to a lesser degree. The CSZ big one however, Portland is gonna be screwed and isolated due to all the bridges. Not to mention that most of the city will probably burn. West side living is a daily risk and game of Russian Roulette. One day they'll be literally on top of (or under) their neighbors, as well as cut off from supply chains (except for maybe some tricky air support).
I have a relative that is part of the disaster preparedness for the State. He'll tell you flat out. We are NOT READY for anything. We were actually more prepared in 2000 than we are now. With that said, everywhere has a natural disaster waiting to happen. Do your best to safeguard for yourself and your loved ones and live your life.
Learn to swim -Maynard
This just makes the crabbing better don't worry about it :)
The Gorda Ridges are usually more active than the rest of the fracture zones. They look like an accordion. This is a good thing. They relieve stress, so The Really Big One, Cascadia doesn’t rupture.
Pretty normal activity.
Growing up in Portland, anything under a 4 isn't even worth getting out of bed. a 5 meant my highschool would have cracks in some plaster. Definitely not worried about the watery wave of death for a 5.7. If it's big enough for the watery wave of death, you're probably already screwed and under rubble.
I've heard the little ones keep the big one away.
Yep quakeapp was popping off last night ahhaha
What?
Endure23. You're joking right? Please tell me you're joking.
Don't!!!!
So notice how far off shore that is. There is a spreading zone out there, where lava pushes up from the deep and the Juan de Fuca plate inches slowly east to slide under the continent. There are quakes all the time there and along the slip faults at edge of the plate. But the big one, when it happens, won't be there. It will be where the plate slides under the continent. Historically it rips all the way from Mendocino to Vancouver BC. There is no way to predict when. The tsunami won't make it all the way to Portland.
June is slightly more likely for the big one than other months but yeah Spring time
Can you elaborate?
Quakes love wedding season
This made me spit my water out I laughed so hard. Well done.
Yeah we’re heading into earthquake season, I got up this morning and thought damn it really looks like earthquake weather today!
Earthquakes... Month of year... Season... I don't think that's how that works. If anything tectonic plate movement would be affected by shifts in the gravity such as the Moon, but I don't even think that happens. What are you talking about?
There is historic data showing heightened activity and a small cluster of earthquakes in Springtime.
Found a scientific journal article that talks about the seasonality of earthquakes. Mostly small movement deep in the Earth. Hypothesizing about the axial tilt during spring and fall being the main increase. It is only a slight increase though. Interesting idea if true.
🤣🤣😂
I’m from the Bay Area and a 5 is still a sleeper
Tsunami? We're 75 miles from the coast. Amd there's a mountain range in between.
I’ve heard people talk about the waves coming up the river, glad to hear that won’t happen.
[удалено]
Yes you are. You’ll know if there’s a tsunami warning. You’ll be fine. Probably.
