We're West Coast earthquake experts. Ask us Anything!

What is your best educated guess regarding the Cascadia event, in terms of when it will happen (the next 50 years?), and do events like the recent earthquake in NW Washington State suggest that Cascadia might be stirring?

Good question! Cascadia's last earthquake was on January 26th, 1700 - the story of how we figured that date out, combining Native knowledge and stories from all the way across the pacific, of The Orphan Tsunami is really fascinating and I highly recommend it. Based on offshore records, there's an understanding that earthquakes happen on this subduction zone every 200-600 years, so, that's a pretty wide time range.

GPS measurements on the fault do show that the fault is "locked," and we could have an earthquake on it any day now. However, it's impossible to predict exactly when that day is, unfortunately.

So, officially, there is a 15-25% chance a magnitude 8 or greater earthquake will occur on the Cascadia Subduction Zone within the next 50 years. SO a Max 1 in 4 chance.

Could happen during this AMA event, might happen next week, maybe 10 years from now, maybe 40... but there's a still a good chance it won't happen in the next 50 years, or even in our lifetimes.

But there is a chance, and definitely a chance of other earthquakes - which is why we recommend understanding that hazard, and being prepared for it! If you know there's a chance of rain, it is wise to bring rain gear. And besides "the Big One," we also have plenty of chance of other earthquakes that can damage and cause disruption here, like the Nisqually earthquake back in 2001 (or similar earthquakes in 1949 and 1965), or on our many crustal faults, like the Seattle Fault, or Chelan Fault -those are all over the state.

The Recent Earthquake was located deep in the subducting plate - similar to the Magnitude 6.8 Nisqually Earthquake back in 2001. That is a common place for earthquakes to occur here, and while is located in the subducting slab, there is no known relationship between these types of Earthquakes and earthquakes occuring on the Subduction Zone interface itself.

Hope this helps - Maybe PNSN can provide more details once they join! -Brian

So it could happen at any time, but there is a 75% chance it will not happen in the next 50 years. I like those odds.

The most interesting thing I've seen on pnw earthquakes is this presentation from Nick Zentner.

https://www.youtube.com/watch?v=UJ7Qc3bsxjI

He's a really captivating speaker, and his life's work has basically been the geology of cascadia. I've learned more than I ever thought I would want to know about rocks from that guy on Youtube.

Edit: Jump to where he discusses probabilities. https://youtu.be/UJ7Qc3bsxjI?t=2668

Nick is great! Though we don't understand why anyone wouldn't find geology captivating in the first place!
-Brian

How much more damage would the Cascadia quake do vs the Nisqually? I understand substantially more, but are we talking many hillsides, bridges down, pipe bursting, old buildings collapsing, trees uprooted etc? Also, could another quake set off the Cascadia subduction zone?

Nisqually was a 6.8 magnitude. Cascadia is estimated to be about 9 I believe. Formula for energy released in an earthquake [J] is:

Energy released=10^4.4+1.5*m. Plugging in magnitudes gives 3.98(10)¹⁴ J and 7.94(10)¹⁷ J, respectively. So a Cascadia event would be just under 2000 times as strong as the Nisqually quake.

Seismic building codes are updated regularly but you can expect to see major infrastructure damage, both from direct and indirect results of the quake. I am not a civil or structural engineer

Considering the damage the Nisqually quake did to old buildings and bridges, close to 2000 times as strong is a bit mind boggling. Though does the strength refer to the depth at which it occurs? How does 2000 times more strong translate to surface shaking?

Exponential scales can be pretty wild, for sure. This is nowhere near my area and would be better answered by u/WaQuakePrepare but since the strength is just a measure of energy, I do not believe it is directly related to the depth at which it occurs, although there may be some correlation.

Hey, thanks for the answers on overall energy release, those are close enough to show that Cascadia would be significantly larger!
Another way to compare the two is how that energy release would be expressed in terms of Shaking intensity (what level of shaking is felt, what people experience, and what type of damage could happen) over an area. Here is the scale, and details along it to help with the images below: https://www.usgs.gov/programs/earthquake-hazards/modified-mercalli-intensity-scale

Here is a ShakeMap showing shaking intensity from the Nisqually Earthquake: https://washingtonstategeology.files.wordpress.com/2021/02/intensity.jpg
So, Nisqually was definitely not a small earthquake by any stretch of the imagination - Strong to very strong shaking over a wide area. Since this earthquake was deep, the shaking was less intense than it would have been if it occurred near the surface.

For comparison, here's a modeled ShakeMap of the Mean potential Shaking from a Cascadia Subduction Zone, using the same intensity scale: https://earthquake.usgs.gov/scenarios/eventpage/cszm9ensemble_se/shakemap/intensity - So ...short answer, it's significantly larger, over a significantly larger area.

Also, Nisqually only lasted 30-40 seconds, whereas Cascadia will shake for 5-6 minutes. So, there's that.

Hope this helps compare - Brian

That third link is broken

It takes a while to warm up, but should work! (I had the same problem, but it did work - checked before sharing)

-Brian

Thank you! I often escort my aged parent on her visits to the coast, and every time we go, my mind does a visual overlay of mayhem. I just don't see how it would be possible to evacuate from the coast by car. Everything west of I-5 would be affected, I've read, and to me that means buckling roads, downed trees and power lines, ruined buildings and bridges.

Or am I overthinking it?

Nope, I wouldn't say that is overthinking it. We recommend that people near the coast evacuate on foot to higher ground due to those exact reasons (downed power lines, broken roads, etc.). The biggest natural warning sign from a Cascadia earthquake is the 2-6 minutes of shaking. It's always better to know the signs and be prepared just in case!

One app that could be extremely helpful to download for your next coastal trip is the NANOOS Tsunami Evacuation App. This can show you evacuation routes for cities along the coast so you can have that knowledge with you on your next trip! Download the NANOOS Tsunami Evacuation App for your smartphone or other mobile device here http://www.nanoos.org/mobile/tsunami_evac_app.php

-Ethan

Which part of the Seattle metro area would likely see the least amount of shaking during a Cascadia earthquake?

The Eastern side of the Seattle metro area is further from the Cascadia Subduction Zone, but with an earthquake of this magnitude I wouldn't expect that different parts of Seattle would see significant differences in shaking. The ground accelerates in all different directions from the release of energy from the earthquake itself, so it is difficult to predict exactly where (if anywhere) would experience less shaking.

This map shows that across Seattle there will be very strong shaking and provides a better visual https://earthquake.usgs.gov/scenarios/eventpage/cszm9ensemble_se/shakemap/intensity

-Ethan

I find the lack of response to questions about the Cascadia Subduction fault...disturbing.

We were just waiting for the right expert to come along to answer it :-)

Do you have a long-running blood feud with East Coast earthquake experts?

I wouldn't say "Blood feud" but ...things have been a little more shaky between us since wastewater re-injection started inducing earthquakes...
-Brian

As a Washingtonian, I think I'm legally obligated to have a long-running blood feud with California, actually. (j/k)

- Elyssa

Who would win in a fight, you or Lucy Jones?

Tough call, there are a lot of us here, but Dr. Jones is pretty amazing! Fortunately, she's on the West Coast too!

-Brian

Why haven't life safety centers, similar to those in Japan where citizens and school children can practice hands-on emergency preparedness skills, gained popularity in the United States, and could the Pacific Northwest region support a business of this nature?

Great question! I have to admit I had to do some quick research on these Life Safety Centers. What a cool idea!

I can't speak as to why they have not caught on here in the United States, but what I can tell you is that there are a LOT of opportunities for school children and citizens to learn and practice emergency preparedness skills here in Washington.

Some examples include:

* Community Emergency Response Teams (here is a list of active Washington Teams which receive training and certifications https://www.cert-la.com/cert-washington/).

*The Great ShakeOut Earthquake and Tsunami Drill (timely) where students and residents practice protective actions for earthquakes and tsunamis, including practicing, Drop, Cover, Hold On, and tsunami evacuation routes. Sign up at shakeout.org/washington.

*Several schools in King County - spearheaded by FEMA Region 10 Youth Preparedness Council - now offer Stop The Bleed training for students and staff.

*Here at Washington Emergency Division we offer all sorts of webinars, presentations, videos, and outreach events where people can receive instruction and resources to learn more about their hazards, how to make emergency plans, and build go-kits en route to being more resilient. Learn more at mil.wa.gov/preparedness

*And there is so much more. Talk to your local city, county, tribe, fire department, etc... to see what they offer.

-Hollie

Is it true that San Francisco is a ticking time bomb? I have heard that eventually there will be an earthquake big enough to destroy the city. Is the west coast doomed?

The San Francisco Bay Area certainly has well-known signifciant earthquake hazard, and the USGS ascribes a more-likely-than-not chance of a magnitude 7 or greater earthquake there in the next 30 years. However, that doesn't mean it is doomed, or that the city (or surroundings) would be "destroyed," as eartthquake preparedness continues to advance and improve. Such an event would produce a lot of damage, but earthquake safety has come a long way since 1906. - Harold

Growing up in Los Angeles, I associate any seismic activity with Dr. Lucy Jones telling us what we need to know. However, is she as well known in the PNW?

Dr. Lucy Jones is great and we know her here too! We also have other great experts and resources like the Pacific Northwest Seismic Network. - Corina

How close are we to finding a cure for earthquakes?

Unlike fevers unfortunately cowbells have shown to be unsuccessful in curing earthquakes. In all seriousness, earthquakes are a natural part of our world and will continue to happen. While systems like earthquake early warning/shakealert can give us seconds of warning before an earthquake starts we can't predict or prevent earthquakes- Corina

What is your favourite movie?

And why is it San Andreas featuring The Rock?

Honestly, Shin Godzilla is fantastic compared to the U.S. Godzilla films and maintains strong emergency management principles in its story.

​

-Ethan

Bad geology pick: 2012 with the scene of a tsunami overtaking a cruise ship in the Japan Trench.
Good (or at least decent) geology pick: Dante's Peak.

The latter is actually one of the reasons I attribute myself becoming a geologist!

-Daniel (WGS)

Well, my favorite fake movie trailer is Infrastructure from Last Week Tonight. Look it up. Has an all-star cast.

~ Emory

San Andreas is FANTASTIC. I am always down to watch that movie.

- Elyssa

We love San Andreas! Had a blast "live-tweeting" it last year from a number of accounts, but mainly our WaShakeOut account, using the hashtag "SanAndreas":
https://twitter.com/waShakeOut/status/1580386119451308032
Try to provide some reality checks while enjoying the fun! (It did get some good stuff right!)
-Brian

I live in Portland and worry about the inevitable "big one". But I recently heard since the epicenter will be off the coast that Portland won't necessarily get hit with a 8 or 9 point earthquake, that it will be substantially less by the time it gets to us. Is that true?

While the epicenter of a Cascadia Subduction Zone earthquake (the "big one") will be offshore, the shaking will encompass a huge swath of the west coast due to the nature of the fault. We use "shakemaps" to show what the modeled shaking could be like for this kind of event:

https://earthquake.usgs.gov/scenarios/eventpage/cszm9ensemble_se/shakemap/intensity

You can see that Portland will still experience strong to very strong shaking.

About how long of shaking?

A Cascadia Subduction Zone earthquake could have shaking that lasts anywhere from 2-6 minutes depending on how strong it is

-Ethan

Is there a base magnitude minimum for when the Cascadia fault unloads?

Not necessarily, but modeling and historical evidence show we can expect something at a minimum of about an 8.0

First of all, thank you very much for doing this, and your response!

Okay, so, from that map link above - it seems that the strongest effects will be off shore, is this correct? And, if correct, is it the expected tsunami that will likely follow that is expected to do the most damage to Seattle - is this also correct? If so, how large is the tsunami estimate? What I recall watching from the tsunami in japan was it was like a fast moving and massive unrelenting tidal surge. I don't know how high the tsunami wave rose in other locations (phuket) - but recollection is that I think it was higher? If above interpretations are correct what is the assumption for Seattle, about how far "inland" from Seattle is quake damage/tsunami damage projected?

Largest shaking doesn't necessarily equate to largest tsunami impact. The tsunami is generated at the fault itself, because one plate shifts upwards and in doing so lifts the entire column of ocean water. The wave therefore hits Washington's outer coast first, in just minutes, and has the largest impact there. That's due to the small amount of time between the quake and the arrival of the first waves, and also because our outer coast has a lot more land at or near sea level so the waves travel farther inland. Once the waves reach the inner coast they have lost a bit of their intensity (though not that much!), but what really helps on the inner coast is that the inner coast has a lot more high ground. Think of all our cliffs and steep beaches. Much better than a long, flat peninsula like in Ocean Shores.

You can check out different tsunami inundation maps here, and see how the inundation for Cascadia differs based on location! https://mil.wa.gov/tsunami-resources

- Elyssa

Worth mentioning that the level of shake will depend on other variables such as the exact location of the slip, the distance of the slip and the type of land/earth that the seismic waves will encounter along the way. Historically, there are far more smaller quakes along the Juan De Fuca plate than there are full rips. (Full rip: the entire plate slips in one event which, extends from southern Alaska to Northern California.) If I'm not mistaken, the vast majority of partial slips occured off the coast of Oregon. I'm not super familiar with the geology of Portland but, similar areas like Olympia, Tacoma and Seattle are built upon basins with looser soils that tend to magnify the shaking at surface levels. That all said, if I was in Oregon, I'd make dang sure I had an emergency plan in place. No matter if its a full rip or a partial slip located off yhe coast of Oregon, Portland is going to FEEL it.

Yes, we refer to the Basin Effect as being on a bowl of jello! Seattle is actually predicted to shake more during the "big one" than some of the areas around it for this exact reason. (One more reason not to live in the big city... ;) )

- Elyssa

Where do ya'll live and did ya'll purchase earthquake insurance policies for your homes?

I live in Olympia, Washington and I personally do not have earthquake insurance, but am considering it. However, many people I know do. Deciding on whether or not it makes sense to you depends on a lot of factors like, age of your home, type of construction, has it been retrofitted, what the geologic hazards are where you live etc. https://crew.org/tag/earthquake-insurance/

-Corina

Olympia, Wa. We have Farmers Insurance, Stephen La Berge.

I’m afraid a lot of people mistakenly believe their standard homeowners insurance will cover earthquakes. It does not. You need to specifically add it. I have a vague memory about flooding (from the outside) needing to be added separately as well…(?)

That is correct. I've also looked at my renter's policy and it does not cover earthquake events. You can look into separate earthquake insurance policies. Another thing to consider could be parametric insurance which can provide a smaller payout, but gives money quite quickly after the event that can be used for any expenses during a damaging earthquake (e.g., childcare). You can look for more info about earthquake insurance here: https://www.fema.gov/emergency-managers/risk-management/earthquake/insurance

-Hannah

When’s the big one? I’ve been waiting 30 YEARS!!

When I was a kid I saw my Town literally split in 2 from the last Big Earthquake it always shook me to my core..

I know, sometimes the waiting can be so anxiety-inducing... I wish I could give you a hard date, or even a range, but that's not something science can tell us. We don't know when the big one will occur, but we DO know it's going to hit someday because it's happened many times in the past - and there is about a 15-25% chance of it happening in the next 50 years. That knowledge helps us prepare, though, which is why you've been hearing about it for so long - we want everyone to be as ready as possible so when the big one does hit, it hopefully has less of an impact than the last one you experienced. "Never again" can be a trite phrase, but it's one that I think drives our work in emergency management. We never want to let a disaster happen twice; we should learn from a disaster so that we can prevent it, or at least mitigate its greatest impacts, in the future.

- Elyssa

How’s it shaking everyone?

Fortunately right now it is not.

We're here to get you prepared for when it is :-)

-Hollie

What's the news on the New Madrid fault? Any estimates?

I'm not aware of any new news on the New Madrid fault area (between Tennessee and Missouri). It does have high potential for a big earthquake but the last big one was in the early 1800s. Just because no one has lived through something like that in a few generations, doesn't mean the risk isn't there. It is important to prepare and not become complacent. It could happen tomorrow or 100 years from now. According to the USGS, they've projected that for an earthquake of magnitude 7.5 to 8.0, the probability for occurrence is approximately 7-10% over the next 50 years. For a quake of 6.0 to 7.0, the probability is 28-46% over the next 50 years.

~ Emory (Simpson Strong-Tie)

I’m an engineer in Puget Sound.

Do you think that Puget Sound is reasonably prepared for life safety during a code-level seismic event?

How vulnerable are our utilities at this point?

Do you think the design MCEr utilized in our building codes is high enough?

Hello,

I'll let one of our engineers add to this, but my two cents is that with studies like the recent NIST report it would be great to focus in the future on functional recovery and go above and beyond life-safety for buildings, particularly critical facilities. https://www.nist.gov/programs-projects/functional-recovery-buildings-and-lifelines#:~:text=The%20Functional%20Recovery%20project%20is,environment%20to%20withstand%20earthquake%20impacts.

As far as utility vulnerabilities there is a report that looked at vulnerability of transportation and lifelines and ...well the outlook isn't great. https://mil.wa.gov/asset/5d8ba2a03a1b7

-Corina

I think most of our metro areas in high seismic risk zones have a lot of work to do to prepare for the next big earthquake. I'm near the San Francisco Bay Area and we have a lot of work to do too. I'm not as familiar with Puget Sound. As you know, the building codes are designed around life safety but a building designed to code may have significant damage and might be unuseable after code-level event. As Corina mentioned, efforts around a higher level resilient performance are gaining popularity. It is generally a fairly small increase in construction costs to make the building able to perform at a higher level, have less damage, and the ability to recover faster.

~ Emory (Simpson Strong-Tie)

Did you enjoy the movie Escape from LA?

Public information officer surveyed our experts and seems like our folks have not seen that movie.

OK thanks for responding anyway. Personally I love it but I can't say I recommend it.

Thanks for the review - maybe we'll watch it for a future movie event, and point out everything it got wrong - that can be fun!

Brian

I think times have changed the recommendation for what to do during an earthquake, but I still hear a lot of people saying conflicting things. If we are inside a house during an earthquake, what do we do? If we are inside a car, what do we do? If we are outside, what do we do?

What do you recommend for earthquake preparedness to have in your home? What do you recommend we have in our car?

Great question and really timely! Next week is actually the biggest international earthquake drill (the Great Shakeout).

If you feel shaking, the best thing to do is Drop! Cover! and Hold On! If you are able to get under a nearby solid table or desk, get under that. This will help prevent injury from things falling off the walls or toppling over. It's safest to not try to run to another room because the shaking could prevent you from safely walking and knock you over. You should also be aware of any mobility issues. If you use a walker or wheelchair, Lock! Cover! and Hold On!

If you're in bed, stay there and cover your head with a pillow. If you're in a car, pull over, set the parking break and stay in the car.

Here's a great video with some more detailed information about a wide range of scenarios: https://www.youtube.com/watch?v=NHm6ZYfq8Pk

-Hannah

Here is a link to some more detailed info with an Earthquake Safety Checklist:

https://www.fema.gov/sites/default/files/2020-07/fema_earthquake_earthquake-safety-checklist_110217.pdf

Some key things to have prepared are: food, water (1 gallon per day per person), any medical needs for people in your household, first aid kit, important papers and cash, and warm clothes. The document linked above has an even more extensive list that can help you put together your emergency kit for home and in your car.

-Hannah

Is there a certain fault or similar which makes you wince when you think about it?

I know that things like Cumbre Vieja causing a tsunami or Cascadia/Yellowstone being 'due any day now' occasionally go viral, but there's always a certain degree of click bait.

Are there any which legitimately make you uneasy?

https://www.usgs.gov/observatories/hvo/news/volcano-watch-canary-islands-mega-tsunami-hypothesis-and-why-it-doesnt-carry

https://www.newyorker.com/magazine/2015/07/20/the-really-big-one

It's important to note that the chances of any given fault in our producing a major quake in the next 50 years are all way less than 50-50, so none of them are "overdue" or "any day now." The one exception is that we are likely to see another like the 2001 Nisqually magnitude 6.8 quake somewhere in the region, just as similar ones happened in 1965 and 1949. The one that is low probability -- but does concern me the most if it should happen -- is a quake on the Seattle Fault. The combination of its proximity to dense population, its shallow depth, and the chance of it producing a Puget Sound tsunami or lake sloshing all make for potentially very serious hazards. Fortunately, we do think such quakes are quite rare, with 1000s of years between them. -Harold

Definitely. As someone who works on and thinks about earthquakes, tsunamis, and volcanoes daily I wince a lot. The Cascadia Subduction Zone earthquake and tsunami keep me up at night, as do local crustal faults like the Seattle fault, which is also likely to cause a local tsunami that could reach downtown Seattle in mere minutes. The most likely earthquake we will experience in Washington/the PNW is from a deep earthquake like the 2001 Nisqually earthquake. Additionally, thinking about a lahar from Mount Rainier is a scary thought. Hopefully we can all work on preparing now so that we can have less damage in the next event.

Cascadia tsunami simulations: https://www.youtube.com/watch?v=e5PJQW_6k6M

Seattle fault recent news:https://www.seattletimes.com/seattle-news/a-double-earthquake-threat-study-finds-two-seattle-area-faults-ripped-about-the-same-time/

Mount Rainier lahar:https://www.usgs.gov/media/images/mt-rainier-lahar-hazard-map

-Corina

I help operate a low-power FM radio station serving a small area in a major west coast city. Our broadcast area encompasses about 200k people, although very few of them are aware of our existence, in all probability.

In the event of a big quake, we could provide hyper-local news and status updates on infrastructure, public safety, and community services, to anybody with an FM radio.

Except, I'm not sure how we would KNOW anything!

Is there an existing emergency/crisis communication hub that would serve as an information clearinghouse/curator, where we could participate as both consumers and providers of information during the crisis?

That really depends on your location. If you haven't already, we suggest reaching out to your local emergency management office - city or county, depending on the size. If they can't help, your state emergency management office is another good resource. Likely these offices have a network of volunteers or a program you can become involved with or might be willing to start something with you. You could also look into CERT (Community Emergency Response Teams) and see if any nearby are interested in incorporating emergency communications.

- Elyssa

Whatever happened with that "Super Volcano" under Yellowstone National Park?

Great Question! Yellowstone is considered a Super Volcano, because it has had several extremely Large eruptions in the past (2.1 million years ago, 1.4 million years ago, and 640,000 years ago). These were some of the largest volcanic eruptions on earth, but it's not the only volcano to have had eruptions that large. However, those aren't the only eruptions Yellowstone has - Much more frequently, and most recently around 70,000 years ago, it had eruptions of lava flows, more similar to those common in Hawaii. So it's also super versatile in eruption style!

Because of it's explosive history, scientists at the Yellowstone Volcano Observatory (Similar to the Cascades Volcano Observatory that watches the Pacific Northwest Volcanoes) watch it closely for changes, and scientists have been watching the magma chamber beneath Yellowstone for years. A lot of studies have found that much of the magma chamber has crystallized, which could mean that this particular volcanic source's history of millions of years of massive explosive eruptions across the Snake River Plain could be coming to an end. ...But we're glad they're watching it closely. An eruption at a volcano that large (but more importantly, that well-monitored) certainly won't happen without warning.

A key thing to understand about these super-volcano eruptions - they are one of the least likely possible events that could happen to us on Earth.

However, if you want to know exactly what's going on at the volcano, you can always ge the latest updates directly from the observatory scientists, who share a "Caldera Chronicles" blog, here: https://www.usgs.gov/volcanoes/yellowstone/caldera-chronicles

Mike Poland, their Scientist-in-Charge of the Observatory is excellent, and if you want much more in-depth details about Yellowstone, he's answered them in several of our May, volcano-focused AMAs in the past - feel free to check out some of his answers here, too! https://www.reddit.com/r/IAmA/comments/usfmwe/were_volcano_scientists_and_experts_ask_us/

Hope this helps! -Brian

Because of it's explosive history, scientists at the Yellowstone Volcano Observatory...watch it closely for changes

When talking about geological time scales in the hundreds of thousands (or millions) of years, what changes are observable in such a relatively short time scale? And how is it determined that any such change is actually meaningful and not just "noise" in the data?

Good question, and one that I prefer to leave up to the experts at YVO - But most basically, the longer time spent monitoring any active volcano, the better idea they have what changes will look like, so continued monitoring over many years will be really important.

The team there watches volcanoes all over the world, and have become pretty good at separating signal from noise at volcanoes - even at the really big/somewhat different ones. Earthquakes that indicate magma movement still look a lot different, and can be distinguished from earthquakes on nearby faults just from the signals they create - Yellowstone with it's active hydrothermal system, and being located in a seismically active area has it's fair share of both, but they can certainly be told apart.

This is a good and interesting question, so I'm gonna reach out to YVO and see if they can provide additional details on the monitoring, but they may be busy - will update if we get more for you!

-Brian

Do people living along the Salish sea/Puget sound really have anything to fear from a Pacific Tsunami? I'm thinking Victoria, Seattle, Vancouver. Anything coming from the wider ocean would get sapped of a lot of energy coming into the sea, and the islands would do a lot of that too, right?

What is the likelihood of a tsunami forming IN the Salish sea? Is it large enough to allow for a devastating tsunami to form?

Thanks!

The Puget Sound (and other inner coast locations) doesn't have much to worry about when it comes to distant tsunamis that originate in locations across the Pacific Ocean, like Alaska or Japan. However, modeling does show us that a tsunami generated by the Cascadia Subduction Zone will definitely propagate throughout the Puget Sound and Salish Sea and cause both inundation and very dangerous currents. It's something we want everyone on the inner coast to be prepared for, even if the largest impacts will be to the outer coast.

In addition, we know tsunamis have been generated in the inner coast by earthquakes along our crustal faults in the past and will again in the future. While these are much less common (think LOW low probability), they can still have major impacts locally when they do happen.

You can check out some really cool simulations of these waves here: https://www.youtube.com/watch?v=e5PJQW_6k6M&list=PLKpn_ilWjh51SEKRBO9mFJx688fjzYkJm&pp=iAQB

​

- Elyssa

God damn that's complex. Those islands really take a hammering. Thanks for that!

What's interesting is that landslides, both submarine and subaerial, can also displace water in our inner coastal water ways causing tsunamis. On April 13, 1949, a major earthquake hit Western Washington, killing eight people and seriously injuring many more. The official USGS report says the earthquake was a 6.7 with the epicenter at the Joint Base Lewis-McCord area Near Tacoma, a huge section of a 200-foot cliff toppled into Puget Sound three days after the earthquake that produced a tsunami that swept across Tacoma Narrows and reflected back to Tacoma, flooding a group of houses along the shoreline. South of Tacoma, railroad bridges were thrown out of alignment. A 23-ton cable saddle was thrown from the top of a Tacoma Narrows bridge tower, causing considerable damage.

We are still learning more about landslides and their tsunamigenic potential but it's a good reminder that if you see water behaving in an unusual way or pulling away from the shore, whether you feel shaking or not, a tsunami might be on the way so you should head to high ground.

-Danté

They sure do! The inner waterways really amplify the waves and currents. We'll likely see some wicked whirlpools, too. Thankfully, the inner coast will have some warning before the first waves arrive, so anyone on or near the water will want to get onshore and to high ground ASAP after the ground shaking stops. Nowhere in the Puget Sound/Salish Sea will be deep enough to offer true safety for vessels.

- Elyssa

Yes the Salish Sea, Puget Sound, and Strait of Georgia are all at risk to a Cascadia derived tsunami as well as tsunamis generated from local crustal faults and local landslides. You can find tsunami hazard publications for the inland waterways at https://www.dnr.wa.gov/programs-and-services/geology/geologic-hazards/tsunamis#tsunami-hazard-maps and view simulations of tsunami waves from Cascadia and the Seattle fault at https://www.dnr.wa.gov/programs-and-services/geology/geologic-hazards/tsunamis#tsunami-simulation-videos

Tsunamis from distant events like Alaska or Japan may not be as impactful for inundation in the inland waters, but still can cause a navigational hazard to maritime interests and risk to beachgoers.

-Daniel (WGS)

What happens with people who live and/or work in high rise buildings during 8+ earthquakes? I've heard in Seattle alot of the newer buildings have those swaying concrete masts to help, but its only so much a building can do right?

The age of the building, the type of construction, proximity to the earthquake and type of ground it is built on all play into how the building will perform in a big earthquake. Some are more vulnerable than others. Modern steel or concrete high rise buildings built to newer building codes will perform better than some other construction types. Some of the most vulnerable are older nonductile concrete frame buildings and unreinforced masonry buildings. Many cities have implemented plans or are working on them to address these buildings and retrofit to make them safer.

Recently Simpson Strong-Tie was involved in a shake table test of a 10 story building built with a newer construction material type (Mass Timber). The goal of that testing was to evaluate a resilient lateral system. The researchers shook it over 100 times and with some very large earthquake ground motions at the end of the test series and the building performed very well with just some minor nonstructural damage. Read more about it here.

Being on a high story there will be more movement and acceleration during a strong earthquake. The best thing to do is to drop, cover, hold on. Find a sturdy desk to get under and protect your head and neck area from glass and other debris that might be an issue. After the shaking stops, make your way down the stairwell to evacuate.

~ Emory (Simpson Strong-Tie)

What about the newer (last 10 years) skyscrapers we have in downtown Seattle that are 30+ stories? Are we safe on those 30+ floors?

If it was built in the last 10 years, I'd feel pretty safe in it. However all the caveats around the specifics of each building and where it was built still apply. We've got the Millennium Tower in San Francisco that is leaning a bit and it is relatively new.... The arguments around what happened and how much concern there is will be ongoing for some time. That building opened in 2009, so more than 10 years old, but I'd still call it a modern skyscraper. Best is to have an action plan and be prepared wherever you live and work. I always think about all the stuff on shelves over my head and that is probably more dangerous to me than the building. Take a look around and see what might fall on you in an earthquake and get it anchored down.

~ Emory (Simpson Strong-Tie)

I'm a Chilean guy, and I'm wondering if you've studied our earthquakes. Have any of you ever been to Chile for earthquake-related matters? It's a recurring belief among older people that Chileans will experience at least one major earthquake in their lifetime, but in my 31 years of life, I've already lived through about four major earthquakes. Fortunately, my country is very well-prepared for such events (both architecturally and culturally).

I've never been to Chile unfortunately, but it is on my list to do. Simpson Strong-Tie has a presence there and I've worked on several projects determining design loads for our products. If you're interested, here's our Chile catalog. My coworker has been there for some collaborations with local researchers on your earthquake hazards. You're right that Chile is pretty progressive when it comes to earthquake design and preparedness, which is great!

~ Emory (Simpson Strong-Tie)

I love this! When I moved to the west coast I came across some ShakeOut info and actually enjoy doing all the preparedness stuff. Now I nag my in-laws to stock their supplies and read up on safety tips lol. If it weren't for outreach like this I would still be living like earthquakes are something to ignore until it happens.

My question: would you say that the pace of retrofitting in the Bay Area (or any metro you have insight on) is going well? I see retrofitting contractors all over town working on tons of properties. But there's a lot of buildings in this city. You could tell me we're only at 5% earthquake safe and it's a disaster waiting to happen, or you could tell me a vast majority of buildings have been upgraded to modern standards - I'd believe either one because I have no idea what the goal is. Any of you have an idea of where we're at, and maybe compare that to some other earthquake-prone regions of the world?

Hi Goldentone, So glad you're as excited about this stuff as we are! You're ahead of the pack in being prepared and thank you for spreading the word.

Metro areas such as San Francisco, Los Angeles, Seattle, etc. have been evaluating their building stock and the vulnerabilities for a long time. I think Hurricane Katrina really started the resiliency movement to help cities recover quickly after a natural disaster so residents can shelter in place and get back to work rather than leave the area and it takes much longer to recover. I participated in a building evaluation for potential soft or weak story buildings in San Francisco many years ago. We walked the streets and evaluated buildings with more than 5 dwelling units and documented the amount of openings in the lowest story. The City created action plans to address these buildings (often they have tuck under parking or garages/storefront openings in the bottom story and may need strengthening).

I'd say the pace of retrofitting in the Bay Area is going well but there is a long way to go. Most unreinforced masonry buildings have been retrofitted. They're in the middle of retrofitting the soft/weak story buildings. I understand there is a program for certain hospitals to be retrofitted or replaced by 2030. The good news is that city officials are aware of the challenges and are actively working to make their cities safer and more resilient. I think some of the California cities are leading the charge in this area.

~ Emory (Simpson Strong-Tie)

Why are west coast that much quake-prone?

This is because we are located along the Ring of Fire, a very seismically active "ring" around the Pacific Ocean formed by the collision of tectonic plates. Where you get oceanic plates and continental plates pushing against each other, subduction zones form - and these can cause some of the largest earthquakes on earth. They also form volcanoes (hence "ring of fire") and in general squeeze the earth's crust in all sorts of ways. We share this seismic situation with many of our neighbors across the Pacific such as Japan, southeast Asia, and South America.

https://en.wikipedia.org/wiki/Ring_of_Fire

- Elyssa

I live in the Seattle area and my house is 70yrs old, made it through all those quakes and seems to be doing fine...but. Should I add some simpson(or similar) EQ bracing just to be safe? Or if it made it 70yrs can I assume it's a pretty sturdy structure.

Thx!

Your home hasn't been through the "worst case" earthquakes that we often talk about, so it's "Better safe than sorry". If you are worried and have resources it's a good idea to get an engineer to evaluate your home and see if bracing or other solutions may increase your home's resilience. -Corina

Hi Tento66, Great question! Our general rule of thumb is that if your home was built prior to the mid-1980s, there may be some vulnerabilities you should have checked out. As Corina said the best thing is to have an engineer evaluate your home and give you suggestions. Older homes that have a raised floor (there's a basement or crawl space) would benefit from strengthening the connection of the house to the foundation. My house was built in 1970 in California near the Hayward fault. It has survived all the earthquakes it has seen just fine, but that's just because it hasn't seen a large enough earthquake yet. Here's a Seismic Retrofit Guide and a blog post that will give you more information on the topic. Also a short video of the benefits of retrofitting by an owner that retrofitted their business (in an old home) in Napa, CA just before the 2014 6.0 quake there. Many other homes there shifted off their foundation or had other damage.

~ Emory (Simpson Strong-Tie)

Is it true that LOS ANGELES is a ticking time bomb? Is it just a matter of time before "The Big One" hits?

The Los Angeles region also has well-known signifciant earthquake hazard, and the USGS ascribes a more-likely-than-not chance of a magnitude 7 or greater earthquake there in the next 30 years. It is certainly a matter if "when, not if" a major earthquake occurs. However, as I wrote for SF, that doesn't mean it is doomed, or that the city (or surroundings) would be "destroyed," as eartthquake preparedness continues to advance and improve. - Harold

The answer is yes and no! Yes, it's just a matter of time before "the big one" hits. We know we've had major earthquakes and tsunamis on the Cascadia Subduction Zone and other major faults in the past and will again in the future. However, that doesn't make any of our cities ticking time bombs, necessarily... The more we all work toward mitigating the impacts of these hazards, and preparing for them so we can survive and thrive in their aftermath, the less destruction they will wreak when th e time comes. Maybe one day the big one will hit and won't even feel like a big one because we'll have done such a good job of preparing for it! (That's a big dream, but we can hope)

- Elyssa

Is the West Coast of Scotland likely to see any earthquakes in the foreseeable future?

Scotland is not on an active plate boundary, so it does not have high earthquake risk. However, once in a while we do see some small earthquakes happen in the UK.

-Hannah

How is that early detection system coming along?

The ShakeAlert Earthquake Early Warning system has been working in Washington, Oregon, and California on the US West Coast for a little over 2 years now - it doesn't detect earthquakes before they happen, but can provide seconds of warning before earthquake shaking arrives in your location.

Everyone in Washington, Oregon, and California is capable of getting seconds of warning on their mobile phones before Earthquake shaking arrives, thanks to this system, and it's completely free! If you're in Washington, you can learn about the 3 ways to get alerts on your phone at mil.wa.gov/alerts

You can learn more about the whole ShakeAlert system at www.ShakeOut.org. It's Really cool!

The free MyShake App, which is one of the ways to receive alerts, Will be sending out a test alert for the Great ShakeOut earthquake drill at 10:19 on 10/19, so it's great to have a chance to practice getting an alert then doing your Drop, Cover, Hold On!

-Brian

You might be interested in New Zealand's GeoNet.

In a recent small earthquake here I got a phone alert notifying me of a magnitude 4.4 earthquake. I had time to think "what earthquake?" then the house shook. Pretty amazing that the detection and alerting system got an earthquake alert to me 5 seconds or so before the motion reached me. Not useful, but pretty amazing.

We work really closely with New Zealand on earthquake/volcano/tsunami hazards. Since unfortunately for them, they've had so much more experience with quakes in recent years, we learn a lot from them. Geonet does an excellent job communicating about earthquakes, thanks to all their practice with them (especially back in 2010-2011... yikes).

New Zealand has recently implemented a Google/Android earthquake early warning system, similar to our ShakeAlert, but one that relies on phone accelerometers, rather than seismometers on the ground like ours (Our Google/Android alerts are also hooked up to seismometers in the U.S.). So the alert you got was likely not from Geonet, but from Google - Geonet doesn't send information before earthquakes (yet). Phone accelerometer earthquake early warning is an evolving technology that will likely get better with time and research, but still new.

As far as 4 seconds of warning being useful? It's as useful as you choose to make it. Better to know there's shaking coming and take action to protect yourself, than to spend a few seconds after it begins trying to figure out what's going on (though NZ is definitely more experienced and attuned to the feeling than us in WA!), and try to get somewhere safe while the ground is shaking. At least that's the philosophy we're building this system on here.

Hope this helps! - Brian

Going great. Earthquake early warning is live in California, Oregon, and Washington. download an app in the state you live to get seconds of warning:https://www.shakealert.org/

- Corina

So the small earthquake Washington just had. Does that now relieve pressure off nearby faults? Also, had the earthquake been BIGGER would it have generated a tsunami actually in Puget Sound?

Since the EQ in Port Hadlock was a deep plate quake (57km depth) it would not produce a tsunami itself even if it was much larger as no surface deformation would be generated to disturb the seafloor. However, secondary impacts from earthquake driven landslides, as seen in Tacoma Narrows 1949, or seiches from shaking as seen on Lake Union in 2002 could pose a hazard. In all cases, if you feel any shaking and are near the beach be alert and prepared to evacuate!

-Daniel (WGS)

Unfortunately the magnitude 4.3 near Port Townsend does not relieve pressure on any nearby faults. It was quite small and that earthquake had a very deep location, 35 miles down below the surface. It doesn't change the stress on other faults in any detectable way. On the other question, fortunately, even if it had been bigger, such a deep earthquake would be very, very unlikely to cause a tsunami in the Sound. -Harold

What's the weirdest thing in your earthquake preparedness kit?

This may sound silly but I have a small section of a blanket my grandma made for me when I was 8. It is worn out and old, but it is soft and so comforting. Don't we all want something to comfort us when we are in a scary situation?

-Hollie

Weirdest or coolest? wine, chocolate, games, things to do and make your life a little easier when you're in a rough situation are helpful for sure. I am very curious to hear what others answer. -Corina

What a great question! Hmm... I think some of my go-bags have little crystal cats in them (like cats carved out of rose quartz and obsidian and stuff) as comfort items because I'm both pagan and cat parent.

- Elyssa

For me, I'd say prepackaged instant coffee mix. Even if it is not hot, I need to have it especially if I am going to be on my own for a while and want to stay sharp.

-Danté

Why do you keep making earthquakes:( ?

Us tsunami folks gotta do something to keep our jobs! (j/k)
- Elyssa

Don't kill the messenger! We just observe and report them, we don't make 'em! --Harold

Why do you think the usgs chose menlo park as a home? Always wondered.

Far be it from us to try to know the mind of the USGS back in 1954... I'd guess it was the proximity to Stanford University though. -Harold

If there was a large earthquake on the west coast, where would be the worst place for it to hit?

I'm not going to name names, but you can check out our cool tsunami pedestrian evacuation walk maps at the link below. These show you how long it would take at certain locations to walk to high ground, as well as the wave arrival time for the area.

I'll let you come to your own conclusions. :)

https://mil.wa.gov/tsunami-resources

- Elyssa

Realistically, if the "big one" hits how in danger are you if you live a short distance from the coast in a wood frame house built in the 70s?

In the event of an earthquake I always thought it would be best to leave the house and be outside but my area also has a lot of very tall trees and powerlines which seem equally as dangerous to be around in an earthquake. In this case what safety measures during and after an earthquake would you recommendation to the people living in these sorts of places?

Trees aren't usually an issue - unless you know of one on your property that is about to fall anyway, they tend to weather quakes pretty well. Powerlines, though, definitely could come down, which is another good reason to stay inside during the shaking and get under a sturdy piece of furniture. Once the shaking has stopped, you'll want to evacuate inland to high ground if you know your house is inside the tsunami inundation zone. (You can check by looking up your address in here! https://geologyportal.dnr.wa.gov/2d-view#tsunami_evac?0,0,0,0)

To keep yourself safe before a quake, the best thing to do is make sure your big furniture is strapped down so it doesn't become debris you have to climb over (or that blocks your door!) when you are evacuating. You'll also want to have a go-bag packed already so you can grab it quickly on your way out. This will cut down on your evacuation time and ensure you have everything you need when you're heading to safety. You don't need much, just enough to help you survive until you get to a shelter. You can learn more here: https://mil.wa.gov/kits

The other thing you can do to really help yourself is to keep a spare pair of shoes under your bed, or somewhere else that's easy to grab in an emergency. Lots of people injure their feet during earthquakes due to broken glass, shattered furniture, stumbling in the dark, etc. Throwing on some old tennis shoes before you stumble outside may make a huge difference and only takes a second if you've already stowed them somewhere safe.

- Elyssa

We recommend to drop, cover, and hold on during the earthquake and then if you live in the tsunami inundation zone to evacuate to high ground immediately. -Corina

What are your thoughts on earthquake beds? The ones that drop you into a chamber with supplies. Are they actually useful or are they the nightmare claustrophobic coffins I picture them to be?

Well... now that I've looked those up, I think the title of this video summarizes my feelings on them pretty well: https://www.youtube.com/watch?v=2W-EcuKxykM

What we'd recommend is just actually taking some time now to secure the objects around your bed that could potentially fall on you, so they won't. Check out some tips on how to secure your space, here:

-Brian

Is Shake, Rattle, & Roll your favorite song? Or maybe that one by The Cars?

That's a good one! ...I decided to write my own earthquake song (well, parody)

"ShakeOut All Star" -Brian

And the Bellevue School District here in Washington did their own Earthquake Parody of "Shake Rattle and Roll" right here! https://www.youtube.com/watch?v=ixeOerAGQhw - Brian

Personally I like Natural Disaster by Pentatonix... ;) But you can't go wrong with Danger Zone!

- Elyssa

I am a "Bad Moon Rising" fan.

-Corina

Earthquake by Graham Central Station is mine.

While not necessarily my favorite song, I have learned that mentioning Taylor Swift gets a lot of attention (especially for NFL games) so I will say that "Shake It Off" by Taylor Swift comes to mind! I'm sure that Taylor would like you to register for the Great Washington Shakeout on 10/19 at 10:19 AM, where you can join millions of people across Washington practicing earthquake safety.

While we encourage you to participate with everyone, you can register your ShakeOut participation for any day of the year, and drill at a time of your choice. You can also include people in multiple locations through video conferencing.

It takes minutes to register! At least that's what people say ;)

-Danté

"Little Earthquakes" by Tori Amos for me. I like it a bit moody and angsty, just like I like my earthquakes :-)

- Hollie

I moved from the east coast to Los Angeles at the beginning of the year. Any way to handicap the likelihood of "the big one" occurring in the next 5/10/20/50/100 years?

Unfortunately, no. They're gonna happen.

What we can do is mitigate the risk to ourselves and the people around us by retrofitting buildings, and strengthening the way they are built. And of course understanding how to protect yourself when an earthquake occurs - here's a link on how to do that https://www.youtube.com/watch?v=NHm6ZYfq8Pk

Also, Practice makes prepared! Sign up and participate in the Great ShakeOut this October 19th! www.shakeout.org

Unfortunately, no. We are at the mercy of faults and anyone who says otherwise is trying to sell you something - usually something VERY expensive! But what you CAN do is reduce the likelihood of that big one significantly impacting you by mitigating the hazard and being prepared for it to occur. Retrofitting your living space, securing furniture, and building go-bags and other preparedness supplies will go a long way toward ensuring you survive and thrive in the aftermath if the big one does happen in our lifetimes.

- Elyssa

Is there a way to find the earthquake rating of buildings?

There's not a rating system that has been universally adopted that I'm aware of, but there are efforts to provide a way to evaluate buildings and classify their ability to withstand natural hazard events along with how resilient they are (ability to recover quickly). The U.S. Resiliency Council has a program for building rating that may be helpful https://www.usrc.org/usrc-rating-system/
~ Emory (Simpson Strong-Tie)

Will there ever be a time where California breaks off and Nevada becomes a seaside state?

California can't really "break off" of Nevada as they're both part of the North American continental crust (which is apparently like a layer cake! https://news.berkeley.edu/2010/08/25/north_american_craton_layer_cake). For California to break off, it would have to be floating on top of the Pacific Ocean, which it is not. It is firmly attached to the rest of the continent.

Now, that doesn't mean that California won't one day be underwater! Parts of North America have been underwater before (check out https://en.wikipedia.org/wiki/Western_Interior_Seaway) and will probably be again one day - but in the far future.

Not a good time to buy "beachfront property" in Nevada, is what I'm saying. ;)

- Elyssa

I’d like to know more about how my home is likely to perform during a quake. I’d be willing to pay a premium for this information. Are you aware of any geo consulting services that assess a home for structural integrity during a quake? The average home inspector does not seem to know how to assess this.

Here is a list of seismic retrofit contractors in the Pacific Northwest who have taken a course on seismic retrofitting. https://www.seattle.gov/Documents/Departments/Emergency/Preparedness/2016-08-05\_HR\_Contractors.pdf

As far as I'm aware, that's the best resource we have meeting your request - hope it helps! - Brian

What is the largest Earthquake that could potentially occur in Southern Utah near St. George? Could something as big as a 7 or 8 happen? Just asking because I do not have earthquake insurance added on. I asked my insurance company, and I think I remember them saying even if I added it on, it would only cover 80%, and I would have to cover 20%. I could never in my life afford to come up with the cash to pay %20 of my home value so I will probably never add it on, and just take my chances.

First of all, hello Southern Utah!!! The last earthquake I experienced there was in September of 1992 and I was in 8th grade at Snow Canyon Middle School (see how I just dated myself).

I am going to let the scientists weigh in on the Hurricane Fault's capability, but living with any earthquake risk comes with its own set of challenges and decisions, including whether or not to purchase earthquake insurance. We all understand how expensive it can be.

Because we want everyone to be prepared, we recommend starting out smaller: Learn your hazards and risks in Southern Utah - you are much likelier to experience heavy thunderstorms and flashfloods but earthquakes can and will happen - make a plan for yourself and your family (don't forget your pets), and build kits.

In Utah, you practice your ShakeOut drill in April so talk to Washington County and find out what they do to prepare the community. I have been involved with some of their drills and there are some great people working on preparedness there.

Hope things back in my home state are doing well!

-Hollie

Regarding your question about magnitudes. A magnitude 7 is possible, magnitude 8 is very unlikely. Most faults in SW Utah are so-called normal faults, where the block on one side of the fault slides down relative to the other side. A fault would have to be continuous over a length of more than 200 miles for a M8 and most faults in the area aren't. (although I have learned to never say never) .The Wasatch Fault further to the east might be capable of that, although it is believed to be most likely to rupture in segments, not all at once. Utah geological survey has great info. -Renate

If you had an appealing opportunity that required you to move to Wellington in New Zealand, would you consider it?

The Taupō supervolcano is 350km away. Small earthquakes are common. In 1855 an earthquake in Wellington was so large it uplifted some areas of land 6 meters (see https://www.nzgeo.com/stories/the-day-the-earth-shifted/). Some theorize a decent chance of a magnitude 9 (yes, 9) earthquake sometime in the next 50 years or so per https://www.stuff.co.nz/national/300985077/buried-reservoir-found-off-nz-coast-where-theres-a-1-in-4-chance-of-megaquake .

But hey, it's a pretty place to live and there's no major fire risk here.

Given how many of us are Lord of the Rings nerds, I think many of us would probably answer yes!

- Elyssa

Absolutely., New Zealand is wonderful! We've been working closely with them learning together about our geologic hazards, and what we can both do to help keep people in both countries safer (hopefully in a way that everyone else around the world can benefit from, too) for about 23 years now! Washington and New Zealand are very similar when it comes to hazards, although unfortunately for them, they have a lot more experience dealing with them ...I'd really like that poor island to stop shaking soon, please.

You can learn more about the partnership and some of the earthquake/tsunami/volcano/preparedness research that's come out of it here: "A Fellowship of the Ring... of Fire"

-Brian (Edit was to include name)

Why aren’t there more tsunami vertical evacuation structures on the West Coast? They are all over Japan. How did they find success years ago and we are just figuring it out?

GREAT question. Farther down I talked a bit about how Japan has baked mitigation and preparedness into their culture, in great part because they have earthquakes and tsunamis much more frequently than we do. They also have extensive historical records of these events to draw on, proving through historical loss of life that mitigation efforts like vertical evacuation structures (VES) are vital to life safety. Simply put, Japan a) understands their risk, and b) prioritizes life safety.

Here on the west coast, our understanding of our tsunami risk is still relatively new, at least when compared to Japan. And our understanding of just how many people could die in a local tsunami is even newer. Just decades compared to Japan's centuries. Our last major deadly tsunami was in 1700, long before record keeping began outside of native oral traditions. So we just don't know how many people Cascadia has injured and killed in the past. Because of that, it's hard to get our leadership to care about something that hasn't happened in recent history and "may" happen again in our lifetimes... or may not. Many people want to pass the buck onto the next person and handle things that are problems now.

And I get it, on some level. VES are EXPENSIVE. We're talking millions of dollars. That's too much for a single community to afford on their own. That means they need help from federal grants, local bonds, private entities... whatever they can find. And that takes time. Not everyone feels the same sense of urgency - and of course there are a lot of other disasters to compete with, especially wildfires. It's messy.

Our office is working on this here in Washington, though! We recently completed a study to find out how many VES we need in Washington and where they need to go. You can learn more about it here: https://mil.wa.gov/tsunami#vertical And we have several communities currently working on VES projects. We're hopeful this work will continue to build momentum and that we'll see increased support (and funding) for VES in the years to come.

- Elyssa

What's your best earthquake joke?

What do people who are prepared for earthquakes and James Bond's Martinis have in common?

They're shaken - not stirred.

-Brian

Looking back on the more-recent large quakes that producsed tsunamis (Thailand and Japan), I noticed that their major bays and ports were strategically fortified with large wave-breaking structures and retaining walls. Even then, the tsunami's still managed to topple over and cause mass casualties. I have not seen any similar structures along the Washington coast that would help to dampen the initial tsunami wave impacts. Should the lack of our fortified shores warrant increased concern for residents along (and even well into) our coastline?

Also, I recall hearing a singular historical instance where one of our volcanos erupted on the same day as one of our fault slips. Has there been any new research into how the larger-format quakes with their extended shaking durations may affect (or not affect) today's volcanic regions?

Good questions! I'll let one of our tsunami folks answer the tsunami part in more detail, but short answer is: all 3,000+ miles of Washington's Coast are at risk from tsunamis, and people need to be prepared for it.

For the Volcano/earthquake connection, there is not much evidence of earthquakes "triggering" volcanic eruptions around the world, even in extremely volcanically-dense places - the two major earthquakes you mentioned before: 2004 in Sumatra, and 2011 in Japan - both occurred very close to a ton of active volcanoes, but there was not any volcanic activity associated with the quakes themselves. As for Cascadia - people have lived here for thousands of years, and we have accounts of their stories - in many, the volcanoes have names, personalities, etc. - While we haven't dug too deeply into all the stories, a story of Thunderbird and Whale and Tahoma (i.e., a story where a massive earthquake was followed by an eruption of Mt. Rainier), would potentially stand out!

It's suggested that for a volcano to be triggered to erupt as a result of an earthquake, it would already need to be primed to go, i.e., have a volcanic edifice (main part of the mountain) already full of magma (Like Mt. St. Helens/Loowit in May 1980). All of our volcanoes are currently not in this situation, but are in their background, normal state. And there's still argument going on about whether that 1980 eruption was an earthquake causing a landslide causing an eruption, or whether the magma inside the volcano caused the landslide, and the landslide just released the energy of a magnitude 5.6(ish) earthquake... tough to read the signals when the entire mountain falls apart and begins exploding, each of which makes a massive noise on seismometers.

That being said, it's not impossible - just very unlikely. So What recommend to everyone - make sure that your emergency plans for volcanoes would still work following an earthquake, and vice versa - will you still be able to get alerted and evacuate? Will you still be able to communicate as you need to? Keep those plans separate, as a just in case for a situation that is really unlikely. An earthquake or volcanic eruption could also happen alongside much-more likely hazards, like floods, fires, or severe weather, so keep those plans separate!

-Brian

This is a great question! Flood gates, breakwaters, and other similar maritime features can be extremely helpful for some ports, harbors, and marinas depending on the local topography and bathymetry, but for others they aren't as useful, are too difficult to build, or are too costly. This is true whether you even take the tsunami hazard into account and are just looking at it from a day use standpoint, or for mitigating more common hazards like storms and king tides. With tsunamis it's even more complicated because we may not have a complete understanding of a particular port, harbor, or marina's risk, or the risk might be so great that no breakwater would be high enough to withstand the modeled tsunami. We saw this in Japan - they built many of their seawalls and other mitigation efforts to what they thought was the most likely major tsunami they would experience, and instead they were faced with one that was much less likely but also much more destructive.

Here in Washington we are taking a hands-on approach to this issue by working directly with chosen ports, harbors, and marinas to develop Tsunami Response and Mitigation Strategies, which you can find here https://mil.wa.gov/tsunami#education. These documents focus on the harbor or marina's specific tsunami hazard in great detail, outlining recommended mitigation and response actions they can take to reduce their risk and increase the likelihood that their people and infrastructure come through a tsunami with as minimal impact as possible. We have two in the works right now that will be released later this year.

When it comes to the general tsunami hazard, instead of sea walls we focus on evacuation. For the outer coast, that means ensuring communities without high ground nearby have artificial high ground in the form of vertical evacuation structures. This is something Japan has excelled at and they saved over 5,000 lives in the 2011 tsunami. We have learned much from them and are trying to build as many structures along our outer coast as we can before our own big one hits. You can learn more about these efforts, including how many we need and where we need them, here https://mil.wa.gov/tsunami#vertical.

Ultimately, a lack of seawalls in Washington doesn't mean our people should be more concerned. However, we DO want you to be aware that ANY coastline is at risk for tsunamis - even enclosed ones like lakes! Understand the hazard, know your natural warning signs and be signed up for tsunami alerts (https://mil.wa.gov/tsunami#alerts). That's going to keep you safe no matter where you are.

- Elyssa

I know a lot of people are worried about Cascadia, but I also would like to know if there's anything on tap for Alaska... (hopefully nothing in the Good Friday range)

Also, IIRC that 1964 earthquake was 9.2 (adjusted?) but the shocking thing to me was that it lasted over 4 minutes. How terrifying would it be to be in a quake that strong for that long?

Thanks for doing this!

Great question! The WGS is currently working and modeling and producing statewide results for a AK tsunami event impacting Washington. The model we are using is utilizing a rupture similar to what occurred in 1964 though shifted laterally along the plate to produce the greatest impact to WA.These models are still being run and publication for them pending likely the end of 2024 or early 2025 so stay tuned!

As far as 4 minutes of shaking goes, I have never experienced anything like it personally but would imagine it would be terrifying or exhilarating for sure. Very likely to happen in CSZ though as we have seen similar length events in other subduction zone events.

-Daniel (WGS)

Alaska has plenty of earthquakes, and the hazard of another damaging one there is ever-present. The 1964 Good Friday quake was the 2nd largest ever recorded on the planet - fortunately it's unlikely to happen in that same spot again for centuries. However, further west, there is the chance of a (probably) smaller, but still large, quake and possible tsunami. In 2020 and 2021 there were several of mag 7.8 to 8.1 west of Kodiak Island. And inland quakes are also possible in AK. --Harold

How much have ground-shaking estimates and structural requirements changed over time? Are they increasing due to energy buildup or are structural requirements evolving as well?

Hi K, Good question. Structural requirements are continuously evolving. The building codes are generally updated every 3 years as we learn new things from Mother Nature. As we improve our knowledge of the hazards and building response, the design requirements are also improved. Some of the big earthquakes in California (Northridge, Loma Prieta) had taught us some vulnerabilities and led to code improvement. For example, homes built before the mid 1980's would benefit from a retrofit to strengthen the connection to the foundation. Seismic Retrofit Guide will give you an idea of the areas to focus on.

~ Emory (Simpson Strong-Tie)

Are there resources for finding reputable structural engineers to check out residential buildings? I live in a relatively modern house but have concerns on it wasn't built to earthquake standards here in the South Sound area. Seems like just randomly google searching for engineers brings up plenty of results, but they are mostly bridge or commercial building engineers and don't seem to find much on any mentioning earthquake retrofit and/or verification.

Hey Sir Squatchin' (Great Name!)

Here is a list of seismic retrofit contractors in the Pacific Northwest who have taken a course on seismic retrofitting. https://www.seattle.gov/Documents/Departments/Emergency/Preparedness/2016-08-05_HR_Contractors.pdf

As far as I'm aware, that's the best resource we have meeting your request - hope it helps!

-Brian

Thanks Brian. I was just looking for that. Here's some more good info from the city on the process. https://www.seattle.gov/sdci/permits/permits-we-issue-(a-z)/earthquake-home-retrofit-permit#3.submitplans/earthquake-home-retrofit-permit#3.submitplans)

Here's also a Seismic Retrofit Guide that will give you some more detail.

~ Emory (Simpson Strong-Tie)

I remember reading an article several years ago about increasing seismic activity in the Mojave Desert and Great Basin and whether the more fault tension has been building there rather than along the San Andreas. Has there been any more recent research on this possibility?

This is the article: https://www.wired.com/story/walker-lane-move-over-san-andreas-fault/

https://www.wired.com/story/walker-lane-move-over-san-andreas-fault/

I wasn't aware of that article and I just rapidly scanned through it and I won't comment on the long term tectonic movements, but that area is definitely seismically active. Fun fact: since the publication of that article (APR 18, 2019) there have been several pretty large earthquakes along the Walker Lane: M6.4 and M7.1 near Ridgecrest on July 4 and 5, 2019 (plus aftershocks), M5.8 Lone Pine on June 26, 2020, M6.0 Antelope Valley on July 8, with an M5 aftershock, and an M5.2 Canyon Dam earthquake on May 21, 2023. -Renate

Hi! Which West Coast are you on?

The US West Coast - we're primarily located in Washington, Oregon, and California. :)

- Elyssa

I have more of an after the earthquake question. I live in a smaller, older (1960s) building and I have a few neighbors who are elderly or disabled. I have an earthquake kit, but is there anything I can do to prepare if they need help after a quake?

If they're willing, you could also keep a copy of their emergency contact information, that way if something does happen you know who to call to get them help (or inform if they are moved to a hospital, etc). You could also ask them if they have a way of receiving emergency alerts - if not, you could help them do that. If they don't have cell phones, a NOAA weather radio is a good way for them to get information.

https://www.weather.gov/nwr/

- Elyssa

That's so kind. It's always great to connect with your neighbors before an event and try and get prepared as a community. You can ask them if there is anything you should know about (such as medical needs) and ask if you can help them after an event. Also just knowing your neighbors and check-in in after an event is great to do.-Corina

So, in your opinion, is this a bad time to buy a place on the Oregon coast?

I always recommend that before buying a house people do their research and see if it is located in a tsunami hazard zone and if the house is retrofitted or built to withstand the level of earthquake shaking expected there. Check out this link to see tsunami hazard areas for OR and WA: https://nvs.nanoos.org/TsunamiEvac

-Corina

How's the housing market there?

There's a chance of earthquakes here, and on the coast, that means a chance of tsunamis. This is a risk we have to accept anywhere we live (living in Tornado Alley means... well, tornadoes). But despite studying these hazards, and thinking about them EVERY DAY for work, we still all decided to live here. Control what you can, prepare for what you can't. Here are some resources on earthquake/tsunami hazard from Oregon Emergency Management: https://www.oregon.gov/oem/hazardsprep/pages/tsunami.aspx

(Our tsunami folks might have more!)

-Brian

Y'all have house-buying money? (j/k)

- Elyssa

What are your feelings on Dutch?

Hey, good question - there is no scientifically recognized way to predict earthquakes yet.

As an emergency manager, I wish there was, but wow, think about the implications of getting a prediction incorrect... yikes. We need to ensure that these statements are accurate before they're made - much like weather forecasts - there's a pretty specific way to do that, unlike with earthquakes.

What I can for sure, if there were a way to predict earthquakes discovered, just based on working with a ton of seismologists/geophysicists (and being one myself!) - we would not be able to shut up about it, because that would be amazing and exciting!

Just my thoughts -Brian

Do you believe that planetary locations and solar eclipses have an impact on earthquakes?

No I do not. - Corina

Seconded what Corina said - there's not any evidence that these impact the occurrence of earthquakes.

For a bit of quick physics, too - The force of gravity falls off between any two objects by a factor of distance between the two objects-squared - that force starts to become extremely negligible when you start talking about planets, which are hundreds of million miles away, so ...hundreds of millions of miles away-squared impacts are pretty negligible. We're just about at a distance away where people walking on Earth's surface, despite being so light compared to planets, probably exert more force on our faults than any planets do.

-Brian

Do you mean like if Mercury is in retrograde or during the upcoming Annular Eclipse taking place on Saturday?

I don't believe they have any impact on earthquakes either.

That said, whether the moon is in Scorpio or it is Libra season, it is ALWAYS a good time to consider earthquake preparedness! Learn Drop, Cover, and Hold On and then do one more thing to become a little more prepared.

-Hollie (Libra)