We are Pacific Northwest Earthquake scientists and preparedness experts. Ask us Anything!

Hi! I have two questions.

1: where is the best spot to be during an earthquake? I’ve always heard a door jam but what if you’re out walking or driving?

2: I hear a lot of impending doom stories about the San Andreas Fault. Is there anything that can be done to prevent that from happening or to at least make it less destructive?

Thank you!

1. If you are inside, the general recommendation is to drop, cover and hold on. In general, you want to find a sturdy table that you can get out from easily after an earthquake. As soon as the earthquake has stopped, you will want to get out of the building as quickly and safely as you can. If you’re outside or if you are driving when the earthquake occurs, the recommendation is to stay away from anything that could fall on you (e.g. buildings, trees, other structures).

   1. We don’t yet have the ability to prevent the next big one, so the key is making it less destructive as you mention. Our modern building codes do a good job at life safety although they aren’t intended to prevent damage. More and more communities are looking at ways to make our built environment more resilient so that after an event the structures are still useful and residents can remain and businesses can stay open. One way to make the effects of the earthquake less destructive is to retrofit vulnerable buildings. Check out www.safestronghome.com to learn what you can do to better protect your home and make it more resilient.
      – Emory

Thank you so much. It nice to hear this from an expert.

The door is an interesting one: So just in case people ask you about it, you can explain why it's not ideal with a couple of reasons (and thank you in advance for the help dispelling the "doorway is safe" myth! :-) )

1. A doorway is not the most structurally-sound part of modern construction, although this may have been the case before.
2. If you were in a room full of people and the ground started shaking, and everyone ran for the doorway... it would be a lot like I-5 during rush hour, but even less safe.
3. Many doorways have doors in them... during shaking, these will start swinging around, and could cause additional injuries.
4. Most injuries during earthquakes occur while people are moving, either from trying to run while the ground is shaking, or from falling objects.

...It's best to Drop where you are, Cover your head and neck, and take Cover under something sturdy if available, and Hold On, until the shaking stops.

​

This infographic covers many scenarios: https://www.mil.wa.gov/uploads/pdf/emergency-management/drop-cover-hold-final.pdf

Practice during the Great ShakeOut, one week from today, at 10:18 on 10/18!

More information on how to protect yourself, and how to register (it's fun and free!) at www.shakeout.org

-Brian

Where should I keep my emergency supplies?

I have one backpack for each family member that has first aid stuff, freeze dried food, water packs and purification tablets, etc. plus some lightweight blankets and additional food. They are all in an easily accessible storage closet, but it’s on the lower floor of our house. I will feel really stupid if we have tons of emergency supplies but can’t get to them 😕

Thank you for doing this AMA!

Great question, and good to hear you have supplies for everyone in your household! The right place to store your emergency supplies really depends on the type of home you live in. If you have a garage with concrete floors, it may be a good idea to store it there, since concrete may be more stable. If you don't have a garage available, a closet or storage room works (cool/dark place is especially good for water storage). Regardless, ensure they're located by a door/access point. Personally, I have kits/supplies located in different places around my house, in case one (or multiple) doorways are not accessible after an event.  Also, remember to have a kit in your car, at work/school, and anywhere else all of you spend a lot of time.  -Ilyssa

Many people commute via covered or subterranean methods (I5 express lanes, bus/lite-rail tunnels, soon to be open SR99 tunnel). What can you say about the resilience or safety of these structures during the Cascadia Event given the most likely rupture points and why is/isn't it total near-instantaneous collapse?

In general, ground shaking reduces with depth. So subterranean structures are probably less susceptible to shaking damage than structures sitting on Earth's surface. So that's good. I'd rather be in a tunnel than a skyscraper. But of course engineers use modern building codes and can design structures to withstand whatever shaking we seismologists tell them they should experience, whether buried or at the surface.

Perhaps a more difficult vulnerability is only related to shaking as such; .it is the deformation of the ground...the strain...that can build up when seismic wave amplitudes change as they pass from one soil type to another. So I think the most vulnerable parts of, say the Hwy 99 tunnel is NOT the deep tunnel, but perhaps on the ramps at either end. This is well-known, though, and planned for by the builders as I understand it.

Another damaging physical process is soil liquefaction. It, too, is related to strains more than just shaking strength. But it takes a few cycles to build up the pore pressure to the level where it can't support structures. So liquefaction damage is often delayed by seconds to minutes after shaking starts.

~Paul

Say I'm walking outside downtown when an earthquake hits. All the advice says stay away from buildings, but that's obviously kind of hard when you're downtown and surrounded by them. Would it be better to stay closer to a building/try to find an entrance, move closer to/into the street, or just stay where I am?

Would you give different advice depending on whether I'm in a glass/steel skyscraper section of the city or a old brick section of the city (i.e. downtown core vs Pioneer Square)?

That’s a good question. I’d say the same advice applies whether you are inside a building or outside: drop, cover, and hold on. If you’re outside a building, find the closest protection from falling debris. I wouldn’t consider this expert advice, but if it were me, I’d get under the closest SUV or park bench or something sturdy that I could hid under. I’d say the same hazards exist for both glass/steel and brick buildings. In both cases you can expect dangerous falling debris.
-Emory

Assuming

1. "The Big One" takes out our surface transportation grid via bridges wiped out on I-5, I-90, I-2.

2. The vast majority of people in Puget Sound have minimal (less than 3 days) supplies of all consumables (water, food, meds, fuel)

3. The time-to fix infrastructure will at minimum be measured in Months, not weeks

How will Emergency Management resupply the Puget Sound population with food, meds, water, fuel while we wait for infrastructure to be restored? Air, Sea??? How?

Federal, state and local governments, and non-profits will be bringing in supplies via ships from California and other areas outside of the impact zone as quickly as possible. This will include the Navy. We have identified airports that will most likely still be operational on the east side of Washington. Supplies will be flown there, then moved via land as soon as transportation routes are inspected and cleared. We may also airdrop supplies to pre-identified locations around WA. It all depends on how much damage there is to the transportation network as well as where the damage is. We are also working on hardening key transportation routes.

-Maximilian

Perfect.

We now have supplies In-Region, assumably in bulk, on container ships.

What is the distribution plan for Puyallup, for Bellevue residents? How will those consumables on the water be delivered to the communities outside of direct water contact? Communities assumed now to be also berift of electricity and fuel resupply to drive to pick up points or aid assembly areas?

Let us assume (for example) that fuel supplies will be limited to what's in the car tank, and resupply for emergency vehicles and emergency services only also for an extended duration (Months).

I have a dozen neighbors around me, many who are elderly or with small children, who need critical supplies either in close walking distance (Assuming the Big One happens in good weather), or delivered to them where they live.

What is the last-mile distribution plan?

Organize your neighbors using the free, out-of-the-box Map My Neighborhood plan.

Here's the link for Map Your Neighborhood for anyone curious what that is (thanks for the tip) https://www.mil.wa.gov/MYN

Can't you just drive around the lake if bridges are out, or drive around the sound if the ferries are out? Could be a problem for people on islands although small boat flotillas can really help, like the Cajun Navy.

If the surface roads are truly impassable then I guess we have an impossible situation.

Well in theory in would be great if we could just drive around, however we anticipate that there will be many impediments to roads and bridges. For example we expect that there will be earthquake induced landslides and road blockages from displaced debris and liquefaction. Additionally, some bridges may be damaged or collapsed making passage over waterways difficult or impossible. If possible we recommend that people evacuate on foot whenever possible because you can't rely on driving.

Hey all! Whenever I search Yellowstone on any media, all that comes up is how much seismic activity is in the area and how it’s going to destroy most of North America. Is this all internet rage?

Hi Johnbob-John!

Yellowstone is a popular media topic, and it is a highly seismically-active area, with magmatic activity underneath it! It is also highly monitored, so it is being watched closely. While we don't have any experience monitoring a supervolcano eruption with modern techniques (thank goodness), monitoring techniques are good at detecting precursors of volcanic unrest, such as increasing amounts of volcanic gas emission, seismicity that specifically indicates moving magma, etc.
The Yellowstone Volcano Observatory is one of the 5 volcano observatories run by the United States Geological Survey (USGS), and they're actively monitoring this volcano. If you ever want to get their official updates, check out: https://volcanoes.usgs.gov/volcanoes/yellowstone/status.html

-Brian

Is there any update on when the big one is supposed to hit Seattle? How bad will it really be?

Estimates of the probabilities of earthquakes that will impact Seattle have not changed too much in recent years. However...the definition of "the big one" isn't really well-defined. Most folks think of an M9 offshore on the Cascadia subduction Fault Zone. That will shake Seattle for a long time, but perhaps not as strongly as a smaller (M7?) earthquake on the Seattle Fault. Chance of an M9 megathrust? About 15% over the next 30 years. Chance of an earthquake on the Seattle Fault? Much less...less than about 5%.

To see what an M9 might look like, you can check out http://crew.org/products-programs/cascadia-subduction-zone-earthquakes-magnitude-90-earthquake-scenario

​

WA DNR provides scenarios for other possible regional earthquakes at:

http://www.dnr.wa.gov/geologyportal

​

~Paul

FYI - the linked M9 scenario page is down.

https://dnr.wa.gov/publications/ger_seismic_scenario_cascadia.pdf

Try this one - Brian

Is it the same for Portland?

Similar, but a bit lower. Well, the odds of a megathrust earthquake of M9 are the same. There are some researchers who claim that there are more frequent M8-8.5 earthquakes on the southern Cascadia Fault zone that would impact Portland, of course, more than Seattle. However, those claims aren't believed by all (although the possibility is included in the national seismic hazard maps). The Portland Hills Fault ... which is the crustal fault sort of equivalent to the Seattle Fault ... is not as active nor as large a threat.

~Paul

In a 9.0M Cascadia event, how high would people near the cost need to be in order to survive the tsunami? Would Seattle's various hills, for example, be safe?

Hi super_aardvark!

Great question. A tsunami's height will actually vary dependent upon location due to the underwater landscape (called bathymetry). It is best to look at your local tsunami evacuation and inundation map to know where to evacuate. Oregon and Washington coastal hotels have these maps in every room, and the local city's webpages will have them as well. The Pacific Northwest Seismic Network has links to the inundation maps here.

​

Regarding your question about the City of Seattle and tsunami, we are working on modeling to see what would happen for the Seattle area waterways for a Cascadia Subduction Zone event. The Puget sound is susceptible to tsunami waves and strong currents following a CSZ earthquake as well as a seattle fault earthquake. There could be sloshing water in the lakes, called a seiche, but that will be localized to lakefront properties. A Seattle Fault earthquake however, could cause both a tsunami and a seiche. [Seattle Office of Emergency Management has information on the location and anticipated wave heights here.](http://seattlecitygis.maps.arcgis.com/apps/MapSeries/index.html?appid=0489a95dad4e42148dbef571076f9b5b)

​

There is information on available tsunami hazard maps on the DNR web portal: https://geologyportal.dnr.wa.gov/#natural_hazards

​

-Amanda

​

I live in Seattle and The Big One crosses my mind just about any time I enter a building or get stuck in freeway traffic on my way home.

What is the likelihood of the ship canal bridge collapsing? (I end up stuck on it every day, so.. Please help me sleep at night if you can.)

If I'm in my car in traffic, what is the best course of action to stay safe from falling trees, freeway lights, or crumbling overhead bridges?

How likely are buildings to completely crumble? Would I be safe in my 4th floor of apartment of a newer building, or is it coming to the ground?

I lived through the Loma Prieta earthquake in the San Francisco Bay Area. In that earthquake, the Bay Bridge did have some damage, but did not collapse. A section of freeway did collapse in west Oakland.
So there will be damage to buildings and infrastructure, however cities have learned from these events, and are evaluating and retrofitting structures accordingly. For your apartment building, if it’s a newer building, then it’s built to newer building codes, and should be able to better withstand seismic events than older buildings. Although, there are many factors that go into what sort of damage may occur in a building, for example: proximity to the epicenter, intensity of the earthquake, the structure’s condition, and the soil composition. These and other factors will determine how well the building performs.
-Emory

It's great that the Big One crosses your mind! Its always on our mind too. The City of Seattle has entire office dedicated to preparing for and reducing the risk to disasters. Check out their site here to learn more about what damages are anticipated and what you can do to prepare. Click the "Hazards Viewer" link to see where your home, work, and commute are in relationship to higher hazard areas (liquifaction, etc.)

​

-Amanda

If you are in a car, slow down, put on your emergency flashers to warn other drivers, pull over to a safe spot (away from overpasses, trees, telephone polls and anything that could fall on your car), put on your emergency break, cover your head and neck and wait for the shaking to stop. Then assess your situation to see if it is safe to start driving again and or leave your vehicle, grab our car kit/go-bag and get to a safe place.

-Maximilian

Will we have any kind of warning for the “big one” we are due? Or will it just happen within seconds? Thanks!

We have the capability to provide from seconds to a couple of minutes of "early warning" once an earthquake starts, depending on where it starts and where you are. The system is called ShakeAlert, is operated by the US Geological Survey and is being tested now. It will take awhile to make the alerts public. There are technical challenges in widely distributing alerts to millions of folks within seconds, and there is much education that needs to be done so that people will do the right thing when they receive the warning. Check out: http://www.shakealert.org/

​

Intriguingly, recent large subduction zone earthquakes in Japan and in Chile seem to have been preceded by small earthquakes and/or silent fault-zone creep. This gives us hope that similar observations may be available in Cascadia, but recognizing premonitory activity as such instead of usual fault-zone processes is a huge challenge that we're working on. Stay tuned ....

​

~Paul

If I stick a wind chime in my closet, will the P Wave from the 'Big One' off the coast of Washington move the wind chime and alert me with seconds or minutes to spare for the incoming shaking?

A wind chime in your closet would certainly alert you to an earthquake! However, if it registers the P wave, you are likely close to the source of the earthquake and will only have a few seconds before additional shaking, not a reliable earthquake warning system. Fun fact, Port Townsend, WA had a shop with a sand-tracing pendulum that registered the Nisqually earthquake in 2001.

​

-Amanda Siok

When will we have something similar to Japan's earthquake warning system in operation here?

https://www.jma.go.jp/jma/en/Activities/eew1.html

WA, OR and CA emergency management, the United States Geological Survey, various university partners (including University of Washington/Pacific Northwest Seismic Network), businesses, Tribes, local government and many other partners are working hard together to implement ShakeAlert Earthquake Early Warning. We hope to have a tested, working system that can alert people in WA as soon as possible. We don't know exactly when that will be, as this is a very complex system with a lot of parts that are still in development/refinement. There are pilot users that are currently testing the system and we are working with cellular companies and the Federal Emergency Management Agency to improve the speed with which the public can receive a ShakeAlert. Stay tuned and find out more information at: shakealert.org.

-Maximilian

When an earthquake strikes, is it a better idea to stay inside of a building you know is not structurally prepared for an earthquake or attempt to make it outside?

Typically, you won’t have enough time to get out a building, so it’s better to have a plan for a safe spot. You want to find a sturdy table that you can get out from easily after an earthquake. Make sure to drop, cover and hold on. One of the reasons it’s not recommended to run out of a building is because debris will likely be falling from the building and may strike you.– Emory

Do you put pineapple on your pizza?

Yes, but I always make sure to take the spiny part off the outside first.

-Brian

I do! I like it paired with red onions and jalepeno. This pizza is often called a "Hawaiian Pizza" and Hawaii has earthquake, tsunami, volcano, and hurricane hazards!

-Amanda

Hello! If a big earthquake wipes out internet and cell service, what do you recommend we do/go in case of an immediate emergency?

Hello, if an earthquake wipes out internet and/or cell service we recommend that you listen to emergency responders and follow their instruction. This may come from all hazard broadcasts, NOAA weather radios, reverse 911 or some other method. We also recommend you have an out of area contact that you can get in touch with via landline (yes those still exist some places) and let them know you are OK. If you have an out of area contact be your point of contact there is a higher chance that you and your loved ones will be able to get in contact with them rather than someone near the earthquake area. It's always good to have a plan in place where you will meet your friends/family and follow that plan. Also, it's always good to have an emergency go bag with you at all times and to be ready to grab it and go in case of emergency.

World wide, what populated areas are the most at risk of a catastrophic earthquake and how realistic would it be to expect that within our lifetimes?

Earthquakes occur largely (~95%) on or very near the boundaries of tectonic plates. The most active areas ring the Pacific Ocean... the "Ring of Fire" (apologies to Johnny Cash!). But the Alpide-Himalaya belt from southern Europe through the Himalaya foothills puts many millions of people at risk. While we can't predict earthquakes, I think it's fair to say that there will be damaging and catastrophic earthquakes in these zones during our lifetimes. - Paul

For some specifics, just look at some of the largest earthquakes in the past 100 years: Chile 1960, Alaska 1964, Sumatra 2004, Haiti 2010, Chile again in 2010, Japan 2011, New Zealand 2010-2011 and 2016... Indonesia two weeks ago. Many of those are along subduction zones, or at plate boundaries, but there are still a large number of other devastating earthquakes that occur within plates.

Check with local geology surveys for more detail about seismic hazards in areas. It's tough because they can't be predicted, but there are many faults that are known to be ready to go throughout the world... which could mean less than an hour for now... or it could be not within our lifetimes.

-Brian

Public places currently do not have to say if they are unsafe for an earthquake. Shouldn’t any public space that is likely to collapse in a major earthquake be required to have a warning posted as you walk in? Maybe a grade from 1 to 5 as to how safe the establishment is?

I’m thinking day care centers, apartments, restaurants, houses for sale and rent, etc. A required warning sign would cost virtually nothing and build pressure to get those places retrofit or replaced. Think of it like a max occupancy or food inspection sign that gets posted at a restaurant. Right now the issue of earthquake safety is invisible to most everyone, and short of an earthquake this is the only way I can think of to get the issue dealt with. Has a policy like that been considered in Washington or elsewhere?

Hello efisk666!

Great idea! The City of Portland is actually looking to implement this next year. Portland City Council just approved a policy that would require owners of brick and similar buildings to prominently post signs with the disclosure: "This is an unreinforced masonry building. Unreinforced masonry buildings may be unsafe in the event of a major earthquake". You can read the full article on this here: https://www.oregonlive.com/business/index.ssf/2018/10/earthquake_warning_signs_requi.html

​

This idea is great for creating awareness of earthquake hazards and understanding personal vulnerability. The next step is educating building owners and the public on how to mitigate or reduce their risk by building retrofits and other preparedness practices.

​

-Amanda

In California, some cities required unreinforced masonry buildings (red-brick) to post a sign that they were unsafe in the event of an earthquake until they had been retrofitted. In some cases, buildings had to remain vacant until retrofit and now most have been retrofitted.

Regarding a rating system, the United States Resiliency Council (USRC) is currently working on a system for buildings:

The USRC Building Rating System describes the expected impacts of an earthquake or other natural disaster on buildings. The rating considers the performance of a building’s structure, its mechanical, electrical and plumbing systems, and architectural components such as cladding, windows, partitions, and ceilings.

http://usrc.org/building-rating-system

~Emory

What are the odds a big one hits the Pacific northwest within 50 years? How bad will the destruction be in terms of wealth and human life?

We have those estimates on the PNSN website. For some scientific background, it is fun to review John Vidale's blogpost from 7 years ago! https://pnsn.org/blog/2011/12/28/the-odds-this-year-of-a-megaquake-on-the-pacific-northwest-coast

Or Lauren's from a couple of years ago:

https://pnsn.org/blog/2016/05/30/what-is-the-cascadia-subduction-zone-and-when-is-the-next-big-one-going-to-hit

In general for Cascadia Subduction Zone M9 events, about 14-15% in 30 years

Perhaps 20-25% for a slightly smaller (but still big! M8-8.5) one on the southern half of the CSZ

and about 15% for crustal earthquakes (shallow shakers) on one of the many crustal faults in the region.

But by FAR the most likely is a Deep intraplate fault in the downgoing Juan de Fuca plate---maybe 35-40 miles deep beneath the Puget Lowlands. About 85% chance in a 30 year period.

For damaging potential you might want to check out some of the following earthquake "Scenarios" used for preparedness exercises and planning:

CREW’s Cascadia Subduction Zone Magnitude 9.0 Publication

https://dnr.wa.gov/publications/ger_seismic_scenario_cascadia.pdf (Corrected -Paul)

DNR Seismic Scenario Catalog:

http://www.dnr.wa.gov/geologyportal

Cascadia Rising 2016 After Action Report:

https://mil.wa.gov/uploads/pdf/training/cr16-state-aar-final.pdf

~Paul

​

​

Marshawn Lynch is known for his Beastquake run in Seattle. How often do sporting events register on seismic equipment?

PNSN does this on a regular basis. You can find out more here: https://pnsn.org/seahawks

How does this group feel about tsunami refuge structures on the coast such as the new Ocosta Elementary School?

Hello SadPenguin!

This group LOVES the tsunami refuge structures that are starting to pop-up along the coast. While the preferred option after an earthquake on the coast is to move to high ground outside of tsunami inundation zones, some areas like Ocosta don't have high ground readily accessible. Tsunami Vertical Evacuation Structures are engineered to withstand seismic and tsunami forces and can provide shelter to those nearby, perfect for areas like Ocosta with limited or no access to high ground. FEMA actually has published guidelines on how these structures need to be engineered.

​

Did you know that tsunamis are actually a series of waves and the second or third wave is typically the largest? We recommend that when using vertical evacuation structures, such as the roof of the Ocosta Elementary School, that people stay there through the tide cycle and/or until local officials give the all clear to come down.

​

Thanks for asking this question! Hopefully you can be a HAPPYPenguin now,

-Amanda

Dear Emory Montague,

Will you please adopt me and give me your name? As well as teach us about other faults that could devastate us.

I'm flattered, Olivesandbs, but I just adopted a puppy a few weeks ago and so I have my hands full at the moment. I've heard there is a process where you can legally change your name to whatever you want.

I do have many faults that we can talk about. One of them is my devastating sense of humor.

Thanks for the question!

- Emory

I work downtown, specifically in the Columbia Tower. How many of the big buildings downtown will be able to withstand a big earthquake and what could the damage look like? I know that we had the 6.8 quake back in 2001 and buildings stayed standing.

Hi SpacePanda,

I'd recommend taking a look at the modeled "Seismic Scenarios" on Washington Geological Survey's Geology Portal for some details on potential damage that can be expected from different faults: https://geologyportal.dnr.wa.gov/

While there weren't collapses in the Nisqually Earthquake, there was significant damage to the facades and parapets of unreinforced masonry buildings: in more intense shaking than Nisqually - highly likely in several earthquake scenarios - it is likely there will be more damage to these structures. Seattle has catalogued that more than 1,000 of these buildings within the city: Without retrofit, all of these buildings will be dangerous during an earthquake. Check out some more details on all the work Seattle has done on understanding their Unreinforced Masonry buildings and their hazards here: http://www.seattle.gov/dpd/codesrules/changestocode/unreinforcedmasonrybuildings/documents/default.htm

"Collapses" are much more difficult to determine, since shaking will be variable across areas.

-Brian

Hi Team,

What are the odds of a CSZ event triggering local volcanic activity?

Very low. It hasn't happened before based on geologic records, in Washington (1700 CSZ didn't cause any eruptions) and other Subduction Zone earthquakes around the world have not been connected to eruptions of the volcanoes near them.

Not impossible, but not something that's been seen before.

-Brian

Hey guys!

I guess I'll cut to the chase, relative to local geology, does living on a "rock" matter?

​

For context, I live in the Seattle area and during the Nisqually earthquake, we saw that some areas didn't feel much in the way of anything, the reasoning given at the time was they were essentially on "exposed rock" in a sea of glacier debris. This seemed to be backed up by the shake maps, showing that the valleys and deltas took the brunt but places that were scraped clean by glaciers did fine. Is there any scientific weight to this observation?

Hello, living on a rock does matter! If your house is built right on top of bedrock (exposed rock) the amount of shaking is expected to be less than if your house is built on top of hundreds of feet of fill or glacial material. This all depends on the distance to the fault and the earthquake epicenter, but in general hard rock is better for building on than soft rock or sediment when taking earthquake shaking into account. DNR provides maps of seismic site class (Site class is a simplified method for characterizing the ground-motion amplifying effects of soft soils during an earthquake) and liquefaction susceptibility which give you an idea of the type of material you may be living on. https://www.dnr.wa.gov/programs-and-services/geology/geologic-hazards/geologic-hazard-maps#nehrp-site-class-and-liquefaction-susceptibility

Another interesting thing we are learning about is the way that sedimentary basins amplify shaking in an earthquake. For example the Seattle basin may act like a bowl of jello and shake more as the earthquake waves bounce around and resonate through the basin.

-Corina

I was in Japan when the 2011 earthquake happened. It shook the ground for several minutes. Is it likely that the same type of prolonged shaking will occur in the NW region? Also, are you seeing in increase in any faults that were thought to be dormant? If so, how often does this happen?

Absolutely yes, an M9 Cascadia subduction zone earthquake will cause shaking for several minutes in Seattle. There are two main reasons for this. The first is that an M9 fault rupture will be hundreds of miles long, from northern California to Vancouver Island. The fault slip doesn't take place all at once, but moves along the fault like a zipper, at at a couple of miles per second at most. So a great earthquake is radiating seismic energy (in the form of damaging shaking) for minutes.

The second reason is peculiar to Seattle and other areas that are underlain by deep sedimentary basins. Once the seismic energy gets into these basins it gets trapped and reverberates around like sound in a cave. That stretches out the shaking duration, too.

As to your second question the answer is no. We have seen no systematic changes in seismicity rates associated with any particular fault. It is a bit tricky, however, because earthquake rates fluctuate naturally, and it is a challenge to identify when a change in rate is "abnormal". Therefore we seismologists at PNSN are constantly watching for any changes that might be "significant"!

~Paul

Hello all! I just saw a bunch of news reports about how that tsunami in Indonesia happened without warning, or that something was wrong with the system: it was confusing, but it was definitely bad. How will we know if a tsunami is coming on the Pacific Northwest coast?

Hi Chimborazor, great question. Here in the PNW an earthquake is our first warning that a tsunami might be coming. If you feel an earthquake get to high ground as soon as it is safe to do so (after you've done your drop, cover, and hold on). We have a great warning system set up along much of Washington coast where sirens will wail to let people know that a tsunami is on the way (https://mil.wa.gov/uploads/pdf/Publications/tsunami-ahab-flyer-final.pdf). This is valuable for earthquakes that happen nearby, and for earthquakes that happen far away (such as in Alaska) that may generate tsunami waves that can make it all the way to Washington.

-Corina

I thought the tsunami would have trouble getting past the Olympics and therefore places like Seattle would only see a small wave of 5-10ft. Is that true?

A tsunami wave's origin will depend on where the earthquake occurs.

How does building code account for seismic possibilities in the area? I live in a midrise in an area that has plenty of landslide potential, and I'm assuming that deep piles are used to anchor it in place. Regardless, there has to be limits to the mitigation potential. Would it still be likely to slide if a 9.0 were to hit? How about the 5+1 wood/concrete construction?

The building code accounts for the severity of the hazard based on your location by requiring designs to resist higher forces as the hazard potential increases. The geology of the area also comes into play. A soils report for the site will tell the designer what the requirements are for the foundation depending on the site conditions.

As you state, generally in fill or loose soil areas pile foundations are necessary to support the structure on rock or more firm lower soil levels. In some case, the cost to build in an area will outweigh the value.

~Emory

What's the best economical way to reach family and friends post-disaster when mobile phone networks are either overloaded or down?

I have a Garmin device so I can text and email as long as I have it charged, and have a clear view of the sky. I use it mainly for wilderness adventures, but I carry it in my backpack to work in case something happens.

It would be helpful to hear suggestions for message relay centers, how should family/friends establish a meet-up spot, what's the best strategy for this if you don't have a satellite communication device, etc.

Hi CounterBalanced,

We suggest having an out-of-area contact point - meaning someone who will be out of the area that could be damaged by the earthquake, who you can contact. Suggested method of contact is texting, as it takes up much less bandwidth than a phone call.
Let this person know ahead of time that they will be your contact, and they can be a way to relay messages through: multiple people can reach out to that person, and just send a quick "I'm safe" check in.

Suggestions on this here: https://mil.wa.gov/uploads/pdf/Publications/create%20an%20out%20of%20area%20contact.pdf

​

(More to come on alternate forms of communications)

-Brian

Thanks for answering questions on here! I remember being terrified as a new Seattle resident around 3-4 years ago hearing about the degree of earthquake risk the PNW is in. I'm not sure what's been going on in the meantime, so I'm curious: in the last 3-4 years, would you say you're optimistic about the level of progress the region has made in terms of preparedness?

It feels like the biggest improvement has been in level of awareness, from the community level, up to the government. However, progress is slow.

Some notable improvements:

- The City of Seattle is doing an excellent job cataloging it's unreinforced masonry buildings, and helping to make people aware of how dangerous these structures are

- The Resilient Washington State Report brought a number of experts throughout the State together to brief the governor on prioritizing the best, most efficient steps would be to help improve seismic resiliency following an earthquake. Several activities have begun as a result of this work.

- The Ocosta School Tsunami Vertical Evacuation structure was built (1st one of it's kind in North America!), and there are several other communities in tsunami inundation zones coming together to build these structures to keep their comunities safe.

- The ShakeAlert Earthquake Early Warning system is being developed, and is almost ready to be deployed across the West Coast. In a couple more years, there will be seconds-to-minutes of warning before an earthquake strikes, giving them time to get somewhere safe, and allow technology to take some automatic reactions to decrease loss of life and damage to the economy associated with damaging shaking... but this system still needs a lot of outreach before people are fully trained to understand how to protect themselves, and it is fully able to serve it's purpose

- 2 weeks ready: more people are beginning to understand what is required, and preparing themselves and their communities to withstand and recover from a major earthquake.

- Annual participation in the great Washington ShakeOut has increased for the past 3-4 years... we take this metric to mean that an increasing number of people in the State are taking action to learn how to protect themselves from earthquakes, and to learn about the hazard. If you haven't registered yet, since you're clearly interested in taking action: www.shakeout.org/washington is the place to join us! (It's free)

​

All of these are great steps, so yes! we're optimistic about the progress that has happened so far, and the momentum that has been gained... because there is still a lot to be done.

​

-Brian

From what I have read about the Cascadia Subduction Zone, most of the West Coast would be beyond salvation if the big one occurs. Is this true, an exaggeration or just a scary thought?

Hi O-Hmmm,
"Beyond salvation" is highly sensationalistic. For one, The Cascadia Subduction Zone only stretches from Vancouver Island down into northern California, so it will have most of its impacts in areas directly adjacent to the fault.

That being said, the damage in Washington and Oregon, especially near the coast, will be significant; based on predictions and models, in addition to building damage, and impacts from the predicted tsunami along the coast following a subduction zone earthquake, there will be great damage to much of the critical infrastructure, such as power, gas lines, roads, water, sewer, etc. For a summary of expected damages, I suggest checking out some of the developed scenario reports: https://dnr.wa.gov/publications/ger_seismic_scenario_cascadia.pdf

The other important thing to consider about "beyond salvation" is that, as we've seen in other disasters around the world recently: notably Hurricane Maria last year in Puerto Rico, and the earthquake and tsunami in Indonesia... while rescuers and relief efforts WILL be coming for you, it will take time. Days to weeks, for them to arrive, and longer for infrastructure like power to be restored to more isolated areas... be prepared to be on your own, and self-sufficient for a little while.
For more information on how to start getting prepared, I recommend checking out https://www.mil.wa.gov/preparedness

​

Don't forget, being prepared for an earthquake will also prepare you for other disasters that are more common, like windstorms, floods, winter storms: it's worth it! -Brian

Thanks for the info. It's wonderful to live in Michigan where the weather may be fickle but it, and the geography, will not kill you.

It's always good to be prepared! A good Ice Storm, Winter Storm, or tornadoes out there are just as likely to knock out power for a while... and it's much colder out there!
Everywhere has it's hazards, but that's why you should have a local, county, or State Emergency management office that can help keep you informed about them. I'd recommend getting in touch with them: knowledge is power! Cheers,

Brian

More questions then? So be it. As far as provisions go, does water filtration beat water in containers?

Considering the latest research, how big of a quake would be necessary to cause a small to moderate tsunami in Lake Washington?

A few years back we had a quake here in Kirkland. A 1-2 something about a 100 yards from my house. Seems like an odd place for one. Obviously small quakes are normal, but what causes little things like that in locations like that?

How does snow effect p and s waves and their effects?

Lastly for now, any eta on a public shake alert beta?

Hi again Kilo147, For the first part, both water storage and filtration are important, but serve different purposes. Water storage is what we mean when we suggest being 2 weeks ready: you'll need that 1 gallon of water, per person, per day, stored up so it will be available for drinking and hygeine purposes.

Water filtration, and purification (such as iodine or chlorine tablets, or ways to boil water), are great to have in your home, but should also be part of a "go kit," something you can take with you if you need to evacuate. These items will help ensure that when you find water, you can safely drink it.

Small earthquakes happen all over the place: All of Washington is experiencing a quite a lot of stress from being in a subduction zone... a large block in Western Washington is also rotating due to this stress. Earthquakes are the release of this stress as it builds up: the vast majority of these releases are very small, so very low magnitudes. Your earthquake could have been one of these small energy releases. Did you feel shaking with this earthquake? most magnitude 1-2 earthquakes are pretty much imperceptible, but being that close to it it's certainly possible to feel some shaking. Sometimes small (or rarely, large) seismic energy earthquakes may also be generated by human activity... construction work, mine blasts, or even just really heavy trucks driving by may cause shaking of low magnitudes.

Snow does not really impact P and S waves... unless it is compressed over a long period of time, like the large glaciers on Mt. Rainier, these sheets of ice can fracture in ways very similar to earth's crust, and there are "icequakes," which are very common, detected by seismometers, on and near the vcolcano, and have to be differentiated from earthquakes.

ShakeAlert is having a limited public rollout in the next couple of months in the City of Los Angeles. However, in Washington, there is a need for higher seismic station density. Likely within the next couple of years though (Paul can probably provide more details on station buildout, and what the system still needs). So start getting ready for it now!

-Brian

Challenge accepted!

Q: Does water filtration beat water in containers?

A: Water is water! If you have a guaranteed water source and a filtration tool (like a steri-pen, filter, iodine tablets etc.) then you're prepared! However, if you don't have a reliable source of water and are dependent upon plumbing, it is advisable that you have an emergency supply in containers. Here's a video that talks about water in your go kit made by WA EMD: https://www.youtube.com/watch?v=gkFU_BtRZpI

​

Q: How big of a quake would be necessary to cause a small to moderate tsunami in Lake Washington?

A: There's lots of "It depends" in this question! First, the technical term would be a seiche- a sloshing of water back-and-forth in the lake. Though, an earthquake caused landslide into Lake Washington could technically create a tsunami. Other factors to consider are the depth and location of the earthquake. A shallow earthquake centered nearby can be much more damaging than a deep earthquake located further away. So, the correct answer to this question is "it depends".

​

Q: Obviously small quakes are normal, but what causes little things like that in locations like that.

A: Plate Tectonics! The Pacific Northwest was created by plates smashing into and under eachother. Checkout this map of all the faults and folds (we know of) in Washington State. #geologyrocks

​

Q: How does snow effect P and S waves and their effects?

A: Snow likely won't effect either very much since snow is on the surface. What does impact P and S waves are soil types. Soft soil, like fill and glacial till amplify seismic waves and can liquify. Bedrock and firmer soils "muffle" the waves so they aren't as damaging. Here's a link to a map of liquifaction soils. Click the ground response button in the Map Contents Window.

​

Q: ETA on public Shake Alert Beta?

A: You can learn all about it here: https://www.shakealert.org/

​

Whew!

-Amanda

[deleted]

Most injuries during an earthquake occur when people are moving, and they are hit by flying or falling objects. predicted shaking in some earthquake scenarios will be at an intensity where it is difficult to stand, let alone walk or run to a different area.

If you are in a field, or a building, the best protective action is to drop where you are (whether you're in the field or inside), cover your head and neck, and if possible, crawl to take cover under a sturdy desk or table (to avoid having objects fall on you), and hold onto that cover, and hold in that position until the shaking stops.

Since it could happen at any time: for other scenarios, here's an infographic with some guidance: https://www.mil.wa.gov/uploads/pdf/emergency-management/drop-cover-hold-final.pdf

Also, if you want to practice, and get it into your muscle memory, well, really you can any time you want, but the Great ShakeOut is a great opportunity that is coming up next week: 10:18 am on 10/19. Join us! :-)
www.shakeout.org/washington

The site also has a lot more details about earthquake hazards and preparedness.

​

-Brian

Here's a hard one for you. The building I live in isn't in the best of shape, the ceilings are sagging, the foundation is questionable, and quite frankly it's a death trap imo. At that point, seeeing as I have a full kit ready to go, dressed or no, does the threat of collapse outweigh the threat of falling debris?

Hi Kilo147!

​

Your building certainly doesn't sound earthquake ready, but it is great that you have a full earthquake kit! Most injuries that occur in an earthquake are actually caused by people moving around and getting hit by falling debris. Your best bet in an earthquake is always to drop, cover, and hold-on. Once the shaking stops however, safely evacuating the building until it can be inspected for safety is likely your best option.

There are steps that can be taken to reduce your vulnerability in an earthquake, does the building owner know about seismic retrofits? Do all building residents know about their seismic risk? Have you strapped down and secured heavy items that could cause damage in an earthquake? Here's a "Home Hazard Hunt" guide that is a great place to get started.

​

Thanks for being prepared!

-Amanda

Have you guys ever considered an alternative to land based structures for your emergency management centers? I mean, something that's not a building and won't fall down when the shaking starts.

In a massive storm, earthquake, etc., a lot of buildings will fall down. What won't fall down, or get damaged, is an aircraft carrier. Besides its indestructibility, it's got a flight deck. exceptional resources like the ability to make water and power. It has a hospital, bowling ally, theaters, kitchens, living space, and a crap load more. It's one of, if not the most, survivable platforms in a natural disaster.

Oh yea, it can move too.

In the off season, it can be used as for anything a normal building would. Things like, a hospital, bowling ally, theaters, kitchens, living space, and a crap load more. Also, it would make a great museum.

The Kitty Hawk is in Bremerton waiting to be scrapped. (So hurry) The ship is in pretty good shape. You'd be amazed at how inexpensive a carrier can be to purchase.

Our state Emergency Operations Center at Camp Murray, WA is designed to survive and be operational during and following a major earthquake. It is steel-braced and framed with a base isolation foundation that acts as shock absorbers. It's basically on rollers that roll with an earthquake. We also have our own emergency power and auxiliary communications systems. -- Steven

I’m a geology student, and I often want to help prepare my friends/family for large earthquakes. But whenever I try to talk to them about the science behind earthquakes, and the risks, they always get scared and ask me to stop before I can get anywhere. My belief has always been that if I understand the science and what will actually happen, I’ll be less scared and more prepared but this seems to be the opposite for them. What’s the best way to tell friends, family, co-workers and etc. about the risks behind a megathrust quake?

Thanks for the question, umbreange. Trying to take the "we understand there is a hazard in the are" and translating it into "What this means for your weekend," can be a big enough challenge, but then taking it an additional step and trying to get people to alter their behavior towards preparedness can be an even bigger challenge.

Most importantly, make sure they know that you're trying to explain these things because you care. Earthquakes, tsunamis, volcanic eruptions, they will happen, but you CAN survive! You're providing them with the tools that will help them to get there. Be informed, build kits, make a plan, and get involved.

Also remind them that being prepared for the less frequent devastating events will help them get prepared for more common events, like floods, winter storms, and windstorms, etc.

Finally, another avenue I would suggest is using the Great ShakeOut annual worldwide earthquake drill. It's a fun, yet practical time to start getting that "when you feel shaking, drop, cover, and hold on," reaction into your muscle memory. And 54 million people around the world did it last year, so... peer pressure?

Hope that helps, and thank you for working on getting more people aware of their hazards! ...this is an exciting State!

-Brian

Secondary question. What's the overall stability of Finn Hill? Where I'm at (124th and 100th in Kirkland is basically facing the side I fear of collapse in a large quake, say Seattle or Cascadia. Any info from y'all on landslide risks thereabouts?

Kilo147,

Keep the questions coming! The city of Kirkland actually has identified all its hazards, risks, and vulnerabilities. This information can all be found in their section of the King County Hazard Mitigation Plan. I encourage you to take a look at your neighborhood, your place of work, and your commute routes to see how they could be impacted by different disaster-type events. This plan also includes a list of projects that the City wants to accomplish to reduce their risk. City's are always looking to get the public involved in the development and support of these initiatives. If you'd like me to connect you with the City, County, and this process (they are starting to evaluate new projects now!), please send me an e-mail: [[email protected]](mailto:[email protected])

​

-Amanda

Here are some maps that were made several years ago of King County, in collaboration with the Department of Natural Resources.

http://your.kingcounty.gov/dnrp/library/water-and-land/flooding/local-hazard-mitigation-plan-update/landslide-hazard-map.pdf

I believe there has been some recent research on mapping the city of Kirkland, (but Sorry, I wasn't able to locate it right now!). I would suggest reaching out to the City of Kirkland Emergency management for more local information about those hazards in your area.

-Brian

If a cascadia subduction zone quake occurred, would there be a correlated rise in volcanic activity? Would the topology of the (non-volcanic) Cascade range change in any way?

We can't predict with any certainty, and it is always fraught statistically to correlate two unusual or rare events. However some large subduction zone quakes globally MAY have been associated with magmatic unrest. This could be a result of subtle increases in pressure within magma chambers caused by shaking loose bubbles. Well that's one wild-hair (wild-hare? I never know which it is...) hypothesis, anyway. However by no means are eruptions clearly correlated with large earthquakes on the megathrust fault always, or even commonly.

As to the topography of the Cascades changing due to a megathrust earthquake. Any changes would be imperceptible probably except to the most sensitive geodetic measurements. Land level changes would be dramatic (~meters) along the coast and offshore (and hence generating tsunami), but that falls off fairly quickly with distance from the rupture so that by the time you reach the Cascades...not much permanent deformation action. Primarily the mountains would lurch probably a few centimeters to the West, rather than up or down.

~Paul

Not impossible but there has not been in the past, in Cascadia or other subduction zones that we've seen rupture.

The Cascade range wouldn't change at all, but along the coast, there would be a co-seismic subsidence - the ground level dropping suddenly during the earthquake - of around 6 feet!

Here's an article describing this phenomenon: https://www.nature.com/articles/ngeo1876/figures/1 9note, the photos are greatly exaggerated.

-Brian

Thank you for this AMA! My question: It's hard to convert magnitude numbers to scenarios sometimes, especially when the odds are of an earthquake occurring "somewhere in the NW" within x years, as opposed to in a specific location. What would you estimate to be the odds that the city of Portland will be hit by an earthquake within the next 30 years that will cause significant damage to homes / cause some of them to shift off their foundations?

Hello Foxask! Thanks for asking a question!

You're right, it can be challenging to convert scientific modeling into scenarios and then communicate those impacts in ways that are both meaningful and understandable. Let me know if you have ideas for how we can improve! The City of Portland actually has a document which assesses the probability of earthquakes, where the damages are likley to occur, and what should be done to prevent those damages from occurring. You can view this document, the Natural Hazard Mitigation Plan here. I suggest looking at the draft plan towards the bottom of the left column and the City Hazard Maps in the middle column.

​

Specific to your question, and taken from the 2016 Portland Hazard Mitigation Plan: (Page 166)

A magnitude 9 Cascadia Subduction Zone earthquake has a likelihood as high as 14% for occurring in the next 50 years. The Portland Hills Fault is located along the west bank of the Willamette River and can produce a Magnitude 7 earthquake with an estimated 1% chance of occurring in the next 50 years.

-Amanda

Thanks for the AMA!

If you are in a URM building, would you still have the same advice of hiding under the nearest desk table? Should you try to leave the building?

Thank you for participating!

Yes, the same advice still applies, and it is especially important in URM buildings; (The other piece of advice would be to try to get your building retrofit).

The most likely part of a URM to collapse are parapets and brick facades being stripped away (see pictures of Fenix Underground in Pioneer Square after the 2001 Nisqually Earthquake). ...Those collapse right into the street and sidewalk... so exactly where you would be attempting to run.

Drop, cover and hold on, is currently the best protective action when you are inside of a building.

Don't forget to register for ShakeOut (Free!) and practice your drop, cover, and hold on with the rest of the world at 10:18 on 10/18 (Next Thursday morning!) www.shakeout.org/washington

-Brian

How can you figure out if your apartment/home is up to earthquake standards?

Good question!

The less expensive way than having a structural engineer come evaluate your house is to check a number of things for yourself: I recommend FEMA's "home Hazards Hunt" publication for some guidance on what to look for:
https://www.fema.gov/media-library-data/1420417719892-b9b41636569f3c41eea88e70ddfae2e2/FEMA528.pdf

It's a good start at least, for the easiest fixes you can do yourself - Which can still make a significant difference in the damage done to your home by shaking.

Hope that helps!

-Brian

How best to deal with powerlines? I've heard to treat all as live....unfortunately if family was in the house and all surrounding us went down, we'd effectively be trapped in side, assuming there is a inside.

Supplies: how many weeks should be planned for?

Puget Sound Energy (one of our larger utilities in Western Washington) recommends treating all power lines like they were live, yes. https://www.pse.com/safety/electricsafety/pages/downed-power-lines.aspx

​

We recommend at least getting prepared for two weeks. https://www.youtube.com/watch?v=8VV7b1VSAYs&list=PLaYp9JZofBz1eT2-iNezh95YJeOuldXiN&index=5

Noticed that the PNW quake array is "different" this morning--lots of smaller quakes across a wider distance, both in WA and CA. Any thoughts?

Well I just took a look and don't really see anything out of the ordinary. At least in the Pacific Northwest. I take it you are looking at the r/https://pnsn.org/earthquakes/recent webpage? The overall pattern, with concentrations of earthquakes at Mt. St. Helens and Mt. Rainier, a smattering across the Puget lowlands and up northward to the border with Canada, and a few pops out east.

It is fun to use the https://pnsn.org/events?custom_search=true page and select a range of time and/or location and the the "Analyze" tool and explore the variability. Of course by the time you figure out what all the knobs and dials are you will deserve an advanced seismology degree and be competing with us academics for research grants! ;-)

~Paul

Thanks for doing this today! I do use the Analyze tool--I really watched the Wooded Island Swarm, a few years ago, for example. But, today there were quakes 30 miles S of Yakima and also in Tri-Cities area--unusual to have both areas in this more quiet region. (I'll leave the research to you!)

Paul

Yes, indeed, today is a bit special (but then again isn't every day? ;-) The earthquakes south of Yakima are a bit intriguing. There were a couple of M4 earthquakes in the late 1990s, but then zilch up until about 2010 and since then every so often a little pop or two at mid-crustal depths (~15 km or so). The tempo doesn't seem to be increasing, but rather decreasing. ... AND our ability to locate small earthquakes there, while not great, hasn't changed a whole lot in recent years (one difference, however is that for the past year or so we're able to use real-time data from some of the temporary portable stations we put out to monitor the Union Gap landslide...but that's really pretty minor). Thank you very much for your interest. It is very gratifying when people are interested in what you do!

-Paul

...But then again just to the west of the past weeks earthquakes was a very active little swarmlet (maybe 20 or so earthquakes in a couple of days) in late 2017 that made us pay attention. They have tapered off and I thought they were over...maybe these are somehow related? Maybe not, though. One of the many little intrigues we have to keep us attentive!

A couple thoughts; One is that WA has a lower Station density than California, so the areas they're better at detecting the smaller quakes we have on a more daily basis, are spaced out a bit more. If you look at the WA map on any given day, it is likely that there will be small clusters of events around Mt. Rainier, and Mt. St. Helens, both because these volcanoes are seismically-active, and also because they both have a lot of monitoring equipment on them. There are more seismometers around urban areas, too, so smaller quakes can be detected.

California seems to have earthquakes much more frequently, and they have a much more dense seismic network. Also, those quakes that appear on the PNSN page are "Out of network."
Check the PNSN and the California Integrated Seismic Network (CISN) for a more complete picture of what is happening in both of these regions. http://ncedc.org/seisMapLeaflet/index.html?org=cisn

Hope that helps!

-Brian

Does climate change have any direct effects on how earthquakes and volcano eruptions occur?

Good morning Ruinevil,
The one thing i can say for certain is that Tsunami modeling is taking modeled sea-level rise into account when they predict how high inundation will be.
Beyond that, modeling the potential impacts is challenging. Predicted increase in sea level does increase the weight of the oceans, which cover around 70% of the planet (Water is heavy!). Changing this distribution of weight around the planet from the poles would certainly change the way that stress stress is contained in the crust, which could potentially impact earthquakes and volcanic eruptions. Changes in precipitation may impact the shallow hydrothermal systems of volcanoes as well, but it's tough to say what this means about it's activity overall, since the biggest changes in volcanoes occur deep underground and within their magma chambers.

BUT... it could also take many many years for any of those changes to cause impacts. For instance, some parts of earth's crust are still rising after the weight of glaciers one mile thick left, 10,000-14,000 years ago. These changes take time.

...So that's all thoughts, speculation and a bit of rambling.

​

Short answer: it's possible, but it's really hard to predict all of the impacts that will happen, especially when we're unsure exactly in which ways the climate will change, especially long term.

-Brian

Is there a northeast team?

I can answer for seismic monitoring networks. Yes! New England is covered by a seismic network that is operated out of Lamont Doherty Earth Observatory of Columbia University. It gets less action than many networks...but there have been big damaging earthquakes in Cape Anne ... awhile ago (1755--off of Massachusetts) and the more lively Charlevoix seismic zone on the Canadian side of the Hudson river with at least 3 M>6 earthquakes since the 1600s, and quite a bit of smaller earthquakes!

Or maybe you meant is there a Northeast team in the Northwest? ;-) Small shallow earthquakes directly under Spokane in 2001 ( https://assets.pnsn.org/notable/WEBDIR_01062514151n/overview.html ) or the occasional little pop in the Okanagan...

Cheers!

~Paul

I'm curious what seismic activity could mean for active volcanoes in WA. Even if we don't see a "big one" soon, how concerned should we be about seismic activity with respect to volcanic activity? Will there be warning signs?

Washington has five volcanoes that are active: consequently, they have a lot of earthquakes associated with them. Each has it's own level of "background" activity (Mt. Rainier and Mt. St. Helens both might have several to tens of small earthquakes in a normal day, and these aren't any indication of increased volcanic activity. However, since increasing seismic activity is one of the first detectable signals that a volcano might be preparing to erupt, USGS Cascades Volcano Observatory (CVO) closely watches these volcanoes, in addition to other parameters (Gas, heat flow, deformation, etc.), so that they can get an idea of when a volcano will erupt. Volcanic eruptions in the cascades will not occur without warning. ...how much warning we would get between unrest and an eruption really depends on the volcano, and how quickly rises, but generally anywhere from 2 weeks up to... it could take years.
Check out more information on monitoring in the cascades, and the various volcanic hazards here: https://volcanoes.usgs.gov/observatories/calvo/

​

On the other side, if you're asking whether earthquakes trigger volcanic eruptions... always possible, but highly unlikely. Looking at all the earthquakes that happen around the world every day, and eruptions that started shortly after, there is not really any definitive relationship between the two. And here in the PNW, we know the exact date of the last Cascadia Subduction Zone earthquake was January 26th 1700, but there are no records of volcanic eruptions that occurred in any of the cascade volcanoes immediately after that. ...So, possible an earthquake could trigger some activity in a volcano with a magma chamber that is already primed and ready to go, but unlikely.

-Brian

How safe are most modern skyscrapers in a "Big One" scenario?

The F5 Tower is supposibly the safest due to its mega bracing, but the vast majority of new highrises seem to do the bare minimum. I'm especially curious about the building under construction at 2nd and University/Seneca with its huge W columns.

Modern skyscrapers are designed to modern building codes which are more stringent. The building codes are constantly evolving to address new things we learn in natural disasters. For high rises, often they're designed using performance based design. In performance based design, you design for the performance you're looking for rather than designing for the minimum code requirements.

The code minimum is intended to ensure life safety. When it comes to critical structures they're often designed for improved performance such as lower damage potential or immediate occupancy after an event.

~Emory

Hi Team,

I’ve read that it’s best to just let pets find their own way to safety during an earthquake. Is this true? If not, what do you recommend doing with pets (inside or out on a walk)?

Hi knotduck,

That's what I've seen as well in reading as well, and I have to agree. When an earthquake strikes, the best protective action is to drop, cover, and hold on. Most injuries in earthquakes occur while people are moving, and chasing after a pet will certainly increase this likelihood. Certainly important to protect yourself if your pet wants to bolt though, to make sure that they have someone to run back to.

If I find more information on this I'll share!

-Brian

Former Geologist here. In school we were taught that the Richter magnitude scale was outdated and that everything should be applied to the modified Mercalli scale for easier to understand damage to surrounding areas. Despite being taught this, every major news station or media coverage still uses the Richter to describe seismic events. Why is this and do you think people would better understand severity if the Modified Mercalli was used more often?

Good question!
So there is a difference in what Richter magnitude and Mercalli magnitude measure. Richter measures the energy release of an earthquake, and many seismologists now use the comparable, but more accurate measure of Moment Magnitude (calculated based on the total amount of slip along the fault).

The Mercalli scale measures the intensity of earthquake shaking, so it is based on how strong shaking is felt.

One big difference is that an earthquake has only one Magnitude, but has many different intensities. It is best to think of intensity like a lightbulb in a dark room: If the closer you are to it, the more bright it is (and you might even feel some heat from it), but as you move further away from it, you experience the brightness and heat less and less. In an earthquake, there are a lot more factors which impact how intensely you experience shaking, especially which types of soil or rock you are on while the shaking occurs.

Mercalli Intensity is what is indicated by USGS's ShakeMaps. https://earthquake.usgs.gov/earthquakes/eventpage/uw10530748/executive For an example, the 2001 Nisqually earthquake was a magnitude 6.8 earthquake. however, people experienced it at Mercalli intensities from IV (shaking is felt), up to VI-VII (Strong, to Very Strong)

Hope this helps!

-Brian

what is the biggest mistake that people always make during an earthquake?

The most common injuries following an earthquake are injuries from debris and glass.

Maximilian says that the biggest mistake people make are not keeping shoes by their bed. So, their feet get cut up as they try to evacuate.

Also, people will run out of a building not thinking, instead of doing what they should: Drop, Cover & Hold on. More info: https://www.earthquakecountry.org/step5/

Is there any chance of a major tsunami ripping through Puget sound or would all of the different little islands help break it up?

A tsunami is modeled to impact the entire Salish Sea after a Cascadia subduction zone event, though it will be smaller (but still plenty dangerous) by the time it reaches these areas.

For reference, it is better to think of a tsunami as a fast-moving tide than as a wave: waves are just energy disturbances on the water's surface; while tsunamis and tides are displacement and movement of the entire water column: it does not "break up" when it hits islands in the same way, but the islands and things will impact the currents that occur around it. Consequently, the tsunami has a lot more force behind it than a wave (both when it flows onto land and as it flows away), which is what makes it more destructive.
https://www.youtube.com/watch?v=1MDnlcbRMaQ - This is the impact of the 1-meter tsunami that arrived in California following the 2011 Great Tohoku Earthquake in Japan.

Tsunami modeling for Puget sound is something that is currently being improved, but what is important to understand is that even though the wave will be smaller, and will take longer to arrive (providing time to get to safety) it is still incredibly dangerous.

Hope this helps!

-Brian

NOAA Cindi Preller recently commented that megaquakes (magnitude 8.5+) occur in swarms, and we're in one now. There have been 6 in the past 15 years, and none in the prior 46 years. How does being in an active cycle of megaquakes change the probability that a Cascadia Event will occur?

Her webinar on Tsunamis, is at https://primetime.bluejeans.com/a2m/events/playback/828307dd-9b09-4494-8736-b629fa005a2c At 00:54:40 NOAA official Cindi Preller is discussing the periodicity of megaquakes, and then the energy released by a quake at a given intensity.

​

That's a good question, but I'm afraid I probably don't have a satisfying answer. There have indeed been a lot of M8.5+ earthquakes in recent years relative to the preceding 50 or so years. Whether you want to call that a "swarm" or not may be open to debate. It certainly is a clustering. None of those earthquakes has been in Cascadia, so I'm not sure how it could change the probability of occurrence of a Cascadia megathrust earthquake. My intuition tells me not at all. Time-dependent earthquake probabilities are difficult to deal with and there is a litany of scientific papers about whether and when and how and if they are really any more accurate than just assuming an average rate of occurrence. Not my field. I think the problem is made more complicated and chancy if the time dependence has to do with earthquakes not from the area you're interested in.

Sorry for the long-winded, and ultimately wishy-washy, response!

~Paul

Do you think that earthquake insurance is worth it? I have yet to find any reliable information on the actual damage a structure (say a 2 story house built in the 90's) will take during a large earthquake in Western Washington. Some information says that a house will take minimal damage and others say your house will be razed to the ground. In what situation (House built pre a certain date vs after) would you purchase earthquake insurance.

Hi Mime241,

The quick answer is, it depends. The first thing to understand is that most standard homeowners insurance policies don't cover damage from an earthquake. That includes earthquake-caused fires and water damage. Do you have savings that can cover these losses? If not, earthquake insurance may a worthwile investment to help you rebuild and recover more quickly.

Another option you may want to consider is looking into both structural and non-structural home retrofits. Is your home bolted to its foundation? Is your chimney stabilized? Do you have any unreinforced masonry (brick facades, brick chimneys, etc.)? Generally, homes built after 1990 are built with some seismic standards in place, but that doesn't guarantee your home won't be damaged. Insurance can help cover the costs of damage, but it is better to reduce the possibility of damages all together by retrofitting.

The best advice I can give you is to 1. conduct as many non-structural retrofits as you can to prevent damages. 2. understand the limitations of your homeowners insurance and personal finances, and 3. consider hiring a contractor to conduct a seismic assessment of your home for opportunities where structural retrofits can be completed. Here's a quick guide to get you started: https://www.fema.gov/media-library-data/1420417719892-b9b41636569f3c41eea88e70ddfae2e2/FEMA528.pdf

​

Thanks so much for reaching out and taking an active role in preparing yourself and your family for an earthquake!

-Amanda

Hey Mime241,

I don't think I can answer your question about the value of earthquake insurance. It will be different depending on your risk tolerance, type of home and where it is located. Your home is one of the biggest investments you'll make, so preparing it to better withstand the next earthquake and considering earthquake insurance is a good idea. There are a few simple things you can look for (especially homes built before 1985) to determine if a retrofit would be a good investment. The main thing is making sure the home is anchored well to the foundation. You can learn more and download a retrofit guide at http://www.safestronghome.com/earthquake/

- Emory

Also want to do a shout out for earthquake insurance via the Washington Office of the Insurance Commissioner, which does encourage buying it. https://www.insurance.wa.gov/earthquake-insurance -- Steven

I lived on the Olympic Peninsula a couple years ago amd we couldn't figure out why our dog was freaking out all the time. Like fireworks-spazzing with no fireworks. After a couple months she stopped. Our theory was she was sensing activity we could not. Is there any truth to this?

Also I am trying to move back, when is St Helens going to blow again? If its next year I may wait a bit longer! 😀

Hello Twinsrule!

There are often reports of animals acting strangely before earthquakes, but there are also reports of animals acting strangely without seismic activity. :) There are some theories that suggest changes in Radon gas before seismic activity and that that may be what animals are sensing. These theories haven't proven conclusive though! Maybe we should start teaching seismology to parrots and see if they can tell us something?!

​

Regarding Mt. St. Helens, you shouldn't let fear of eruption spoil your moving plans! There are actually five active volcanoes in the Cascade Range (Baker, Glacier Peak, Rainier, St. Helens, and Adams). These volcanoes are all monitored by the Cascade Volcano Observatory run by the US Geological Survey (USGS). We will have advance warning before any eruptions happen, allowing you to evacuate or find the best view. The above link will also allow you to sign up for volcanic activity alerts, keeping you in the know!

​

MarinersRule,

-Amanda

Hi Twinsrule,

Unfortunately all of the reports on animals being earthquake detectors are anecdotal... but they are definitely more sensitive than humans. Seismic sensors are also more sensitive than humans, so... if it happens again, I'd recommend checking out Pacific northwest Seismic Network's page at: https://pnsn.org/earthquakes/recent to see if there are some small earthquakes in your area.

"When" is always a great and usually unanswerable question when it comes to geohazards. Mt. St. Helens is definitely the most historically active volcano in the cascades though, so it is very likely it will erupt again, even if it's not within our lifetimes. The nice thing about that volcano is that it is heavily monitored, so we will get warning that it's activity is increasing before it erupts.

If you want the earliest warning you can possibly get about St. Helens, or other volcanoes in the U.S. becoming more active, I suggest signing up for the Volcano Notification Service: https://volcanoes.usgs.gov/vns2/

-Brian

If "the big one" hits we're looking at possible tsunamis and volcanic eruptions, not to mention Yellowstone. Not to mention the fact that already even on a good year our roads still sluff off into the ditch... what is the safest evacuation route?

With a Cascadia Subduction Zone earthquake (the "big one"), yes, you should expect a tsunami, but there's no reason to expect that it will cause volcanic eruptions (It hasn't in the past).

The landslides that could occur during the shaking are extremely likely, though. Especially if it occurs in winter, or during times when it is rainy. Washington Department of Natural Resources has been working with coastal emergency management offices to learn about what the best evacuation routes are if you're in a tsunami inundation zone (or volcanic lahar hazard zone), so I would recommend checking there first. They do take landslide susceptibility into account when making many of these maps.

-Brian

Is Mt Hood in danger of erupting in the near future?

Xotaec,

That depends on how you define "near future". Your near future or earth's near future according to the geologic time scale? Mt. Hood is monitored by the Cascade Volcano Observatory, CVO and there will be many warning signs before an eruption happens. You can sign up to receive alerts and learn more about Mt. Hood's eruptive past here: https://volcanoes.usgs.gov/volcanoes/mount_hood/

​

What did one volcano say to the other? I lava you!

-Amanda

Hi Xotaec,

Mt. Hood is an active volcano near populated areas, and while it is currently not showing any unusual signs of unrest, it is well monitored! There will be warning before the next time it erupts; there are a number of changes that occur as a volcano goes into an unrest period, and there is a scale of activity from the USGS to correspond to this, from Normal (where it is now) to Advisory, to Watch, to Warning (Eruption imminent, or underway).

If you want to be one of the first to get an update about any volcanic activity in the cascades, the best way it so sign up for the Volcano notification Service: https://volcanoes.usgs.gov/vns2/

-Brian

Do you guys feel like crazy cultists saying "it will happen soon and it will be huge!"?

Some people might look at us that way.
But what we're saying is that things that have happened in geologic and even human history will happen again; and there's plenty of data to back it up. That's one of the main principles of geology: look at the past to understand present and future Earth processes, and vice versa.

Another "crazy" aspect that you can see is not so crazy just by looking at recent events, is telling people to be prepared, and gather supplies. With the amount of damage expected to power, roadways, bridges, etc., it will take time for relief agencies to arrive and help out, even though they will be on their way. So you and your community members will be the first ones looking out for you after a disaster. That's why we recommend getting "2 weeks ready."

It's always a big news story with all the hurricanes, how there is no food, water, or batteries left on the shelves when a disaster is approaching; it's all about realizing that you can start gathering many of the supplies you need now, so you don't create an additional disaster for yourself later.

​

So yeah, in a way, we're sorta like a less-extreme prepper cult, but it is definitely based on science and experience around the world and even around the country. We'd love to have more people "join," because ultimately, it will help your community and the state to recover faster from any disaster that happens.

https://www.mil.wa.gov/preparedness - Here are some good ways to get started!

-Brian