We are earthquake experts. Ask us anything about The Really Big One coming for the Pacific Northwest.

Will this finally end the great hipster epidemic that's plagued the Northwest for close to a decade?

No, there is no hope of ending that. - John

I am curious about Portland. Can you do a basic overview comparison of the issues for Portland versus Seattle? What you've said so far seems to be that Seattle is more about shaking and sliding. Is Portland's issue more liquefaction and bridges collapsing? Are there finer points I am missing? (Thank you, this is a great AMA!)

Portland's buildings are more vulnerable, because Oregon didn't adopt a seismic code until ... the late 1980s. (They thought they were immune from quakes!) Most of the bridges downtown are really old and aren't going to stand up to much shaking. Also, most of Portland's fuel supplies (gasoline, jet fuel, oil) are concentrated on the banks of the Willamette, on ground that's going to liquefy. On balance, I think Portland is going to suffer more. Seattle's utilities are very vulnerable, but some of our major bridges through town - the Ship Canal and the 99-bridge, have been recently upgraded. In both cities, neighborhoods will be cut off and folks will have to get by on their own for quite a well - days, maybe weeks - because emergency responders will be overwhelmed. Sandi Doughton

Buildings in Portland are more vulnerable, because they didn't factor quakes into the building codes until the late 1980s. The old bridges downtown aren't going to stand up to serious shaking, either. And virtually all the city's fuel supplies (gasoline, jet fuel, oil) are stored in tank farms on an island in the river where the soil is going to liquefy. In Seattle, some of our major bridges have been upgraded, including I-5 and 99 over the ship canal, so they're not likely to topple. But in much of the SoDo region, the ground will turn to soup from liquefaction. Both cities have loads of old brick buildings that are going to crumble. And in both, neighborhoods will be cut off and on their own, because first responders will be swamped. On balance, I think Portland might fare worse - but I'm not sure I would bet my paycheck. Sandi Doughton

wager much of

Will Seattle (or anywhere in the PNW, really) ever implement earthquake early warning systems as mentioned in the New Yorker article about Japan?

We are currently testing earthquake early warning in the Pacific Northwest, in fact I have it on my phone now.

It needs more testing and full funding before it is ready to be released to the public, however. - John

Did you see inaccuracies in the New Yorker article or was there anything about it that bothered you?

Overall, it was a well-written and documented article. The scenario left an impression of much greater devastation that is anticipated to occur, however. - John

The scenario left an impression of much greater devastation that is anticipated to occur, however.

Could you amplify that a bit?

Frankly, the article was pretty horrifying, and I saw several people in my FB Portland parenting group flipping out and swearing they'd homeschool rather than send their children to schools that would just crush them in the even of a quake. (The Gearheart school scenario was terrible, too.)

The article says:

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

and:

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

Pick one.

I wonder if that first quote is a little out of context. Sometimes an operating assumption should assume a worse case scenario to make sure you have enough resources for a normal scenario + complications?

Sorry, I went off to lunch. Yes, you put your finger on the quote most easily taken out of context. Communications may black out, transportation may grind to a halt, stores conceivably could run out of goods for a while, but that doesn't constitute "toast" in one's mind. The speaker must have been referring to some aspect of those problems, not to smoking rubble. - John

How realistic is it that 3 days' supplies (the minimum recommended) will enable my survival of the Very Big One in Seattle? And how many days' supplies do you personally have in your home ready for an earthquake?

We recommend people prepare themselves for 7 to 10 days vs. three. For a major quake, life won't be back to "normal" after just three days. I've got enough at home to make it through a week, and also keep a stash of stuff in my car as well as at work.

Beyond supplies, I always encourage people to talk about their plans - especially around communication, which we know will be affected. Where will they be? How can they get back together? Where could they meet if not at home? -Debbie

This is a very selfish question. I love Seattle. A lot of my friends are there, my GF has an interview for a job in town, and it's a place where it'll be relatively easy for me to find work. Assuming we make the move, what should we consider when looking for housing to minimize our own risk in the face of this danger?

I live here, and I personally wouldn't advise anyone to stay away from this beautiful region because of earthquake risks. Some things you might consider when choosing a house: A newer home will be built to stricter codes; if you choose an older home, make sure the house is bolted to the foundation; avoid steep slopes; look for something on solid ground, not fill or loose soil. (You can find geologic maps of the area, or hire an engineer to advise you.) Once you pick you new home, make emergency kits for home, work and car, and a plan for contacting family members (designate an out of state contact everyone can check in with). My philosophy is be prepared, not paranoid - and enjoy the spectacular landscape provided to us by tectonic forces. Sandi Doughton

if you choose an older home, make sure the house is bolted to the foundation

I've read that this is mostly important for multi-story buildings and that single-story buildings are less likely to move off their foundations.

Any credence to that or do I need to go big bolt shopping immediately?

I'm sure the problem is more severe with two-story homes, but one-stories aren't immune. The city of Seattle holds occasional classes in how to do-it-yourself or to help you pick a contractor: http://www.seattle.gov/emergency-management/what-can-i-do/prepare-your-home

Sandi Doughton

Thanks for doing this! A few questions:

• What would you say is the most helpful action(s) that an individual can take to prepare? (whether that is hiring someone to retrofit structure of their house, simply preparing an emergency kit, etc)

• I read a comment from someone on Reddit that there's a difference between a southern Cascadia subduction zone (northern California/Oregon) and a northern one, and that it's the southern zone that is currently more at risk or "due" for a big earthquake, any truth to this?

• How far behind is the infrastructure (regarding seismic event safety) in the Pacific Northwest compared to Los Angeles / San Francisco?

• For individuals, just be aware of the risk, make a plan with your family for how to get in touch after the quake (designate someone out of state that everyone can call or text even when local service is disrupted.) And build your emergency kit. You don't have to do it all at once - I just add things to mine every now and then.
• There's pretty good evidence that the southern half of the subduction zone - off the Oregon coast - snaps more frequently than the northern half. But any subduction zone quake is going to affect the entire Northwest, whether it's a M 8.2 partial rupture, or a full-rip 9.0.
• We are woefully behind most California cities in upgrading old buildings. Unretrofitted brick buildings are virtually nonexistent in most of California- and some cities require warning signs on those that remain. The City of Seattle has nearly 1,000 old brick buildings, and has done very little to require upgrades, except during remodels. Many of those buildings are multistory apartments, and nobody warns the people who live there. LA recently started paying attention to old concrete buildings - 1940s-'70s vintage, which are very poorly constructed and can pancake. We've done nothing about those in the PNW. Sandi Doughton

For Seattle specifically, is the city in better shape to sustain less damage (from the tsunami specifically) because of the Olympic Peninsula. I'm sure Puget Sound levels will still affect coast line, etc. but with the wave caused by the earthquake be partially or fully nullified by the peninsula?

Thanks! I find this type of thing infinitely fascinating (albeit slightly terrifying), but it won't prevent me from moving back to the beautiful PNW one day! : )

The tsunami won't really be a factor in Seattle or Puget Sound. By the time the swell gets here, it will be pretty small. But the quake could trigger landslides here that cause localized swamping. Sandi Doughton

First, thank you SO MUCH for taking the time to do this. My family is up on Whidbey Island -- given the location of the subduction zone, what kind of damage / flooding could we expect to see to the Islands when this happens?

The tsunami will travel up the Strait of Juan de Fuca, and the west side of Whidbey could get smacked. Washington DNR has excellent tsunami inundation maps and evacuation info: http://www.dnr.wa.gov/programs-and-services/geology/geologic-hazards/tsunamis Sandi Doughton

We all know the Alaskan Way Viaduct is toast, but are any of the other major transport routes in the Seattle area particularly vulnerable? I-5 ship canal bridge? I-90 floating bridge? Is Seattle going to be completely cut off if the big one hits? Is it time to move to Spokane?

Hundreds of bridges in Washington have been retrofitted, including the ship canal bridge. But hundreds more haven't been. Washington's resilience plan estimates it could be months before all major transport routes are reopened, though emergency routes - the airport, etc.. - will open up before that. But parts of Seattle will definitely be isolated, which is why the recommendation is to be able to survive on your own for at least three days and perhaps a week. The coast is expected to be cut off completely, probably reachable only by boat or air. Sandi Doughton

Immediately after a big quake, yes, we do expect major transportation routes to be affected. We will mobilize bridge inspectors as soon as possible, and work to restore and reroute major arterials. -Debbie

How would a major earthquake affect the nearby volcanoes?

The same process of subduction - where one tectonic plate dives under another - is responsible for both our earthquake risk and the creation of our volcanoes. In other places, like Chile, volcanic eruptions have followed major earthquakes. Several of Japan's volcanoes became more active after their M 9 quake and tsunami in 2011. But I haven't heard of any good evidence that Mount Rainier or other Cascade volcanoes erupted in a serious way in 1700, the year of our last megaquake. Sandi Doughton ,

Any chance of a NW quake setting off the Yellowstone caldera?

Zero. And a Yellowstone eruption is so unlikely and so prevalent among questions from the public that it is a major source of irritation to many scientists. - John

Two questions:

1. You say the average frequency of such an event is 1 in 300 years. Do you know if the distribution is roughly uniform? My guess is that it would tend to decrease over time -- but I've also just googled and found articles that suggest continental drift is actually speeding up. Or is the distribution of big earthquakes something that we don't really have a good handle on at the moment?

2. I've heard and seen that the probability distribution of a large earthquake follows approximately a maxwell-boltzmann distribution (in other words, the probability of an earthquake with energy E varies like exp(-E*const)). On the other hand, I've seen you say that the maximum amount of energy in a fault system can produce an earthquake of approximately X amount. So I'd like to understand which statement is making the bigger approximation at large energies. Is there actually a probability that the Pacific Northwest can have, say, a 10.0 earthquake (exponentially less likely than a 9.0), or is it physically impossible for the fault system to store that much energy?

I can't answer the second question, but on the first: The terrestrial record shows evidence of about 20 M9-9.2 quakes in the last 10,000 years. The evidence is a combination of buried soils that indicate the coast dropped by several feet, and sand layers deposited by tsunamis. Dating those layers reveals a rough chronology, which shows some of the most powerful quakes were separated by 900 years, and some just by 200 years. The evidence of an additional 20, slightly smaller quakes that only ruptured the southern half of the subduction zone, comes from seafloor cores that records a history of underwater landslides. Sandi Doughton

Good question. At the highest magnitude, the magnitude-frequency distribution is no longer exponential. The Gutenberg-Richter distribution is recast as the truncated or doubly-truncated Gutenberg Richter distribution, which reflects approaching a physical limit on the possible size of earthquakes.

I think the global limit is thought to be somewhere around 10. But remember, breakage of Cascadia has a small chance of triggering the Queen Charlotte fault, which has a small chance of triggering big faults along the Aleutians. So in the case of very, very, very rare and large events, one is not limited to just one fault. - John

Hi folks, As someone who works with homeless and underprivileged individuals in a city with almost 3800 recorded homeless people, I am especially concerned about how an environmental catastrophe would affect or displace folks with low income in Seattle. How might you recommend someone without a home, car, or place of business prepare for a major earthquake?

Preparedness comes in all forms. People with the fewest resources are sometimes the most resilient in the face of disaster because of their circumstance. Community connections will be extremely important, and coming together with others, knowing your area, knowing who is around you, will all help afterwards. We have done extensive outreach and education with community-based agencies who provide services and have created plans to help their clients when disaster strikes. -Debbie

Some of these questions will require research and then planning. One very good resource is the Great Washington ShakeOut. Participation will be enlightening, and they supplied materials that answer a lot of these questions - John:

http://www.shakeout.org/washington/

What are the chances "the big one" will never come in our lifetime? How much do most of us not understand about probability and statistics when it comes to natural disasters like earthquakes?

If the chance it will come is 15%, the chance it won't come is 85% (if we're expecting to live another 50 years). However, there are plenty of "pretty big ones" to worry about as well, so you're overwhelming likely to see some action in the PNW. - John

Statistically, we're more likely to have another deep source quake like the Nisqually, that occurred in 2001. Chances for another one are above 80% within the next 50 years. -Debbie

When we say "Seattle", will the earthquake disaster/tsunami actually hit the city of Seattle? Or are we referring to the coasts of WA? In other words, do the people within Seattle (downtown, etc) and even neighboring cities like Bellevue, have to worry about these affects and 100ft waves?

The 100ft waves are even rare in great earthquakes, more often the waves are 10 to 30 feet, and they will not be nearly as big in the Puget Sound. So shaking, not waves, are the threat to the Puget Sound from coastal earthquakes. - John

Say it's doomsday. I'm living alone, playing video games and eating a pizza to myself on a quiet Friday night. Suddenly all the dogs in the neighborhood begin barking in unison. What's my first move? Do I go into the street to avoid a building collapse? Duck and cover? Join in on the barking? I'm sure there are a lot of factors at play here but I'd guess that most people haven't planned their first move here.

I would go outside to see what the dogs are barking at. It's more likely to be a prowler than an impending quake. Sandi Doughton

Duck and cover. And while you're ducking, concentrate on watching out for stuff falling, and don't come out until the shaking stops. - John

How would the skyscrapers and the space needle in downtown Seattle fare against the big one?

Almost half the tall buildings in Seattle, Portland and Vancouver BC were built before anyone knew we could get this kind of megaquake in the Northwest. It wouldn't surprise anyone if some of those older buildings collapsed in a major quake. Newer skyscrapers are much better designed, but under current building codes, all they have to do is NOT collapse. If the building is completely unusable after the quake, that's fine per current codes. Some engineers are pushing for stronger standards that would allow buildings to be resilient, and reusable soon after the quake. The Space Needle was built with redundant support systems and the heaviest steel available. I'm betting on it to survive. Sandi Doughton

I am from Vancouver and we have a suburb Richmond that is in the middle of the Fraser River delta. I have often heard that when the earthquake hits Richmond will be completely submerged and destroyed because it is all loose sediment from the river. How realistic is that?

I don't think Richmond will be submerged, but it's likely to get pretty soggy as the ground liquefies, which will damage building foundations and create a lot of problems. Sandi Doughton

Were large-scale earthquakes considered during the planning of the current waterfront tunnel project? What extra technology and structure is being implemented to prevent catastrophic damage to the new tunnel and seawall?

My impression is the designers of the tunnel are very cognizant of the strength needed to withstand earthquakes. It is not, however, designed to survive movement on a fault crossing the tunnel, which is very unlikely. - John

Extensive planning went into the design of the tunnel and seawall, including considerations for earthquake, fire in the tunnel, rescue operations, hazardous materials as well as life safety issues. The new seawall is higher and built as a modern structure, designed to withstand a much level of impact than the existing structure. -Debbie

If a smaller quake hits does that lower our chances of the really big one? Like would it relieve the tension on the plates?

Probably just the reverse, alas. If only a portion of the offshore fault breaks, that will increase the pressure on the rest of the fault, raising the changes of another quake. That kind of one-two punch happened in the Indian Ocean after the 2004 quake and tsunami. The second quake /tsunami wasn't nearly as destructive as the first, though. Sandi Doughton

What's the chance of previously dormant cinder cone like Mt. Tabor or even worse, not-so dormant Mt. Hood/St. Helens/Bachelor/Sisters, joining the party once it kicks off?

About 10% of great earthquakes trigger a volcanic eruption, and most eruptions are fairly minor, so the volcano risk is small compared to the earthquake risk. - John

Can you give an estimated timeframe, and a rough degree of certainty?

For the M9 along the coast, the best estimate is 10 to 15% chance per 50 years, or 1 in 300 each year. - John

This presumably increases over time as the potential energy in the fault builds? i.e. The more years since the last event, the greater the probability? I assume the increase in probability is not in a direct linear relationship with years since the previous event.

It does increase, but not as fast as you might think. The odds basically peak out at 20% per 50 years. The interval between M9s has been as long as 800 years - the fault does not get "10 months pregnant" with skyrocketing odds at any time.

According to city maps, my home (built in 1970) sits on soils that are susceptible to liquefaction during an earthquake. As my biggest investment, including a source of future retirement income since it is a rental property, I want to protect it as much as possible. What is recommended as far as retrofitting? Everyone here seems to be strapping their house to their foundations, but in liquefied soils, the soil under the foundation goes, right? What's the recommended retrofit option in these circumstances?

Check with a structural engineer to see what you could do. They can provide an assessment and talk through different options for you. -Debbie

I'm renting a house that was built in 1938, so I don't want to spend a ton of money earthquake-proofing a house I don't own, but are there any low-cost things I can do to help my house not crumble if the Big One hits?

Yeah, I'm wondering what--if anything--renters can do.

Considering the rentals market in PDX right now, pressuring landlords to invest in seismic retrofitting probably wouldn't go down very well...

I think tenants SHOULD pressure landlords. In Japan, businesses are willing to pay more to rent earthquake-safe buildings. But in the short term, you can make your rental space safer by securing anything that could fall on you - shelves, heavy items, televisions, etc... Sandi Doughton

This is a bit dreary question, but how likely do you think people in Seattle/Portland/etc. are to actually pay attention to the data and start preparing for potential earthquakes?

Human nature is the same everywhere. Some will pay attention and get prepared, others won't. We all need to press our state and local governments to improve infrastructure so the region will be able to recover more quickly. Sandi Doughton

How big is really big?

The biggest quake ever seen is M9.5, the biggest we expect to ever see is around 10. Here in the Pacific Northwest, M9.2 is the high end, the range of estimates from 1700 go from 8.8 to 9.1. - John

I'm guessing quakes couldn't ever be prevented, but could we get to the stage of predicting them to a high accuracy? If so, how far away is this technology?

There are some promising developments in detecting signs of accelerating activity on the seafloor. The great earthquakes recently in Japan and Chile had active earthquake swarms in the weeks leading up to the events. We'd like to cable some instruments on the seafloor to keep a closer eye on activity here. - John

I've heard about "earthquake lightning" and rainbow light things that some people think come before earthquakes. Are these completely bogus/coincidence, or are these actually real things?

The internet yields a strange mix of scientific studies and conspiracy theory youtube videos on this topic

Bogus/coincidence. YouTube is a goldmine of wonderful nonsense. There are no compelling observations and no theoretical reason to expect it. - John

Every attempt to predict earthquakes has fizzled. But it is possible to detect the initial seismic waves and issue what's called an earthquake early warning, that could give Seattle a few minutes' warning before the strong shaking hits the city. Japan has a system like this and so does Mexico. A version is being tested in California and could be expanded to the West Coast if there's enough funding. Sandi Doughton

What are the chances that my home owner's insurance policy, to which I've added earthquake coverage, would pay out if the Really Big One hit?

I would say the chances are excellent, as long as the insurance company is solvent. The catch with most earthquake insurance is that the deductible is sky high- 20-25 % or more of your home's value. So unless the damage is severe, you might not get anything. Sandi Doughton

What would be the long term effect on Seattle after the big one? Could it recover?

Yes, we can and will definitely recover! There has been extensive planning in place for several years. The City's Recovery Framework outlines the basics: http://www.seattle.gov/emergency-management/what-if/plans -Debbie

Let's cut to the chase... how high high will the water get in Ballard?

You might see a little coastal swell in Ballard, but the tsunami will not be a major factor there. Sandi Doughton

Hi, I live on the Southern Slope of Queen Anne. My sister lives on the water in Normandy Park. We are wondering what would be the best thing to do when this earthquake hits? Would we be safest staying in our respective condo and home? Or should we get in our cars and try to drive to the Eastside? I am guessing I90 and 520 will be in bad shape. So what would be the smartest escape plan? Thanks for any help you can offer.

Actually, it is safer to stay where you are. Getting on the roads will only create more congestion and depending on the damage to bridges and streets, you honestly may not get very far. Smartest plan - take a protective action, keep yourself safe, check on others and help them afterwards. -Debbie

Thank you, that makes sense. Are there any preventative measures we could take to "keep ourselves safe"? I feel like my condo will collapse and slide down the hill. My sister's house will likely be underwater. So if we are to stay where we are.. where can we find reliable information about precautions we can take to survive?

We expect most of our homes and structures to fare relatively well, especially if you are a wood-frame construction. For condos, there are other ways to reinforce the structure - it's worth having a structural engineer do an assessment. Check with your homeowner's association. For homeowners, especially for homes built before around 1980, bolting the house to the foundation through seismic retrofit will help it survive. -Debbie

This passage from the article really scared me: "… in the I-5 corridor it will take between one and three months after the earthquake to restore electricity, a month to a year to restore drinking water and sewer service, six months to a year to restore major highways, and eighteen months to restore health-care facilities."

I assume that the author means "full" restoration of those services, but to the extent even major degradation remains for those periods of time, that is scary and seems to suggest keeping far more than seven days of supply on hand. Can you please comment on this passage? Accurate?

Yes, it is accurate. You can find those figures and more in the Washington and Oregon Resilience plans, easily googled. Here's an article I wrote with more details on expected outages and their likely duration: http://www.seattletimes.com/seattle-news/planning-for-the-megaquake-and-after/ Sandi Doughton

I live in a basement apartment. The walls are mostly concrete, I believe. What would be the best strategy for me to not get crushed if this thing hits Portland soon? Also, how bad is it anticipated to effect the east side of Portland?

Get yourself under a table, desk or countertop - even in a basement apartment. Ideally, you'll be tucked underneath and can make your way out from under after the shaking. -Debbie

What will happen to the people that live in places like Bandon or Gold Beach that will experience soil liquification?

Anyplace on the coast will be heavily damaged by the tsunami. Estimates of possible wave heights range between 30 and 60 feet in places. Oregon has great maps of the areas expected to be innundated by the tsunami - you can find them on the state emergency management web site. Sandi Doughton

Sandi Doughton

Is there anything that an apartment dweller can do, besides making sure they have an emergency kit, food, water, an out-of-state contact, and know their evacuation meeting point? I feel like my hands are a little tied because I can only do so much in terms of preparing my very old building.

Get together with other folks in your building - find out who has what skills, i.e., knows first aid, willing to knock on doors, can control utilities, etc. Create an emergency plan for your building, and find out who else lives in your neighborhood. Connections matter after a big disaster, having them ahead of time is even better. -Debbie

Hello, I'm an Alaskan. I am wondering what we might expect up here if there is a 9.2 quake in the Pacific NW. Would shifts there cause quakes on the Aleutian Megathrust?

Alaska is too far to have much seismicity triggered by a quake in the PNW. A fair tsunami might travel up there, but it would be nothing compared to the waves you'd get from your own M9s. - John

Two questions:

First the New Yorker article cites a 1 in 3 chance that the big one will happen in the next 50 years. That seems high based off of the 1 in 300 chance cited elsewhere in this thread. (but I haven't taken many stats classes) Is this based solely off of that number, or is there some other stuff I'm not aware of?

Second a couple other faults have been referenced elsewhere in the thread. What other faults exist in the area, and what risks do they pose? What kind of quakes can they generate, and how likely are they to "go off"?

The gold standard, the Goldfinger odds (actually there are some contentious debates) give 1 in 3 odds for southern Cascadia, but only 1 in 6 for the northern part where we Puget Sounders reside. That is because southern Cascadia is claimed to be hit by an extra M8+ every 500 years in addition to the M9s that strike the entirety of Cascadia every 500 years. - John

Which of these is better for when the quake comes?

• 1921 three-story brick walk-up

• 1908 single family 2-story home

• 1966 attached townhome

I would definitely stay away from an un-reinforced brick structure of any kind, but I'm not sure I can intelligently choose between the other two. If the single family home is bolted to the foundation, it's a pretty good bet. Wood frame construction is pretty tough - and flexible. Sandi Doughton

Thank you so much for doing this guys. I have a question that was nagging me last night trying to get to sleep:

You've already touched on volcanoes not erupting, but I'm curious if there's any concern for the Really Big One to trigger a shift of the glaciers on Mt. Rainier (or any of the Cascade peaks) that could cause massive lahars?

The article mentioned nothing about it, and I'm hoping its no concern, but after growing up in Orting, Washington, where we heard that a lahar could happen at any time and all it would take is some shifting on the mountain, a big earthquake turns my blood cold.

I think that's a reasonable thing to be concerned about. Most lahars off Rainier are triggered by eruptions, but for at least a few of them, volcanologists have found no evidence of an eruption at the same time. There is a lahar warning system in the Puyallup Valley, though. Sandi Doughton

Hello! What's your favourite seismic activity?

Volcanoes are constantly generating weird noises, whereas the coastal subduction zone is generally ominously quiet. So whenever we're bored, we take a look at one of the 10 active volcanoes in the PNW. - John

What are the chances of a "Big One" hitting the east coast?

There are very few and very slow faults on the east coast. The chance of a "big one" there is nil. Even an M6 hitting New York or Boston would make a mess, however, and occasionally quakes hit near there. - John

I know Chile and Japan have high standards for buildings and construction, I am from Peru and all buildings are made of concrete. Are developers in Seattle require to commit to anti seismic features in the buildings? How that can be improve in the near future? Is government going to put some legal requirements from now on. What about houses built in the last century? are they way less prepare for a quake 9.2, so how bad is to live in an old building ?

The U.S. has pretty strict building codes, and earthquakes are definitely factored in everywhere on the West Coast. Those codes are simply meant to insure that buildings don't collapse and kill people. But builders here fight attempts to strengthen codes and rarely go beyond the basics - because they don't want to spend more than they have to. There's no requirement for the type of base-isolation construction common in Japan, that allows buildings to jerk back and forth with no damage. Sandi Doughton

You say below that you are testing an early warning system, yet don't these systems already exist in places like Japan? What is the point of testing something that has already proven at least somewhat effective.

The testing is required to give the system accuracy and avoid false alarms, given the instruments and foibles in our PNW system. We know how to do it, but for example, just last month in California, the way the calibration pulses are times fooled the system into thinking a large earthquake had just occurred. When big quakes happen only every few years, we cannot allow a system that generates a lot of false alarms to send signals to the public. - John

Hi there, thanks for doing this AMA!

Do you have suggestions for what to keep in an emergency kit? I don't really have anything other than canned beans and home brew at the moment.

Basics include extra food and water, blankets and warm clothing, flashlights, AM-FM radio and extra batteries, first aid, pet supplies and prescription medication. A good website to check out is: http://makeitthrough.org/ Have fun with it, and take it one step at a time! -Debbie

What about Eugene/Portland? Similar damage/problems to Seattle? Would you advise people to be moving from the area?

Portland has a bit less of a problem than Seattle. It doesn't have the massive basin underneath to amplify the motions and is a little farther from the Cascadia fault. - John

It seems that this concern has been brought up forever.

Why should we be more fearful now then let's say 30 years ago when people were saying that the NW is ill-equipped for an upcoming earthquake? Because the odds are going up? Or is there another reason?

Being in Portland, I assume the city will pretty much be destroyed, our bridges need help, older buildings without much preparedness. Any insight?

Portland will suffer damage, and does need some serious retrofit efforts, but it will NOT be destroyed. Newer structures should do well, and wholesale destruction is not guaranteed. - John

Is there a possibility a cascadia subduction event of the magnitude described in the New Yorker article could trigger a quake in the Seattle fault in Elliott Bay as well?

Sorry, I answered the wrong question. Yes, it is possible for a subduction zone quake to trigger follow-on quakes on shallow faults. There's no evidence that happened in 1700, after the last subduction - but there are a few hints in the geologic record that it might have happened during an earlier subduction zone quake. Sandi Doughton

Which areas of Seattle do we expect to be most affected by a large earthquake? What factors (e.g., building construction quality, ground stability, etc.) go into your assessment?

The worst damage will probably be in areas built on fill- pretty much everything south of downtown. Both stadiums were designed to withstand a lot of shaking and ground liquefaction, so they will like be OK. But anywhere with old brick buildings - like Pioneer Square, the International District, etc.. will be in a world of hurt. Low lying areas south of Seattle - like the Kent Valley, where much of our consumer goods are stored in big warehouses - will also sustain heavy damage because of the loose soil. Sandi Doughton

You keeping mentioning "this tech could happen, with funding." Where can we donate to help with this research? What kind of community outreach is there for earthquake safety?

The earthquake early warning is logically a federal project - that ensure continuity for the decades it should operate, seamless behavior across state lines, and decent oversight by federal scientists.

But donations to the institutions building the project, UW, Berkeley, and Caltech, could speed development and deployment. - John

When did Seattle structural code begin to require buildings be designed to withstand a megaquake, if ever? Without an early warning system, what is the best thing for someone to do if they're living or working in a structure that is not likely designed to stand-up in the Really Big One and they feel the first pulse?

We expect most highrises in Seattle to shake and sway, but ultimately stay standing. When you feel the first pulses - take a quake-safe action - within the first 30 seconds, get somewhere secure like under a table, desk or countertop, and prepare to ride it out.

For highrise residents - it's not practical to think you can leave the building - stay in place where you are during the shaking. Afterwards, the conditions outside may actually be more hazardous than inside. -Debbie

Seattle first began to factor quakes in its building code after a quake near Olympia in 1949. Bigger quakes didn't begin to be factored in until the mid-1990s. Even today, the building code does not require consideration of how long the ground will shake, just how hard. Oregon is in much worse shape, because it didn't even consider quakes at all until the 1990s. Sandi Doughton

Will we have to worry about tsunamis? How much of the fault is off-shore?

For a Cascadia quake, tsunami isn't Seattle's biggest threat. Tsunami comes into play for Seattle during a shallow Seattle Fault quake. Debbie

I work for a Hydrogen-Fuel Cell Backup power supply company, and I am a former resident (30 years) from Seattle. I just recently moved away.

Does Seattle have anything in terms of back up power for utilities in the climate resiliency plan?

Hospitals, emergency facilities like 911 centers, and other critical facilities have back-up generators and plans for utility back-ups. -Debbie

My home is on a relatively steep slope and was built in 1911. The ground is pretty solid glacial till. What do you think the chances of it surviving are if the really big one hits? Other than bolting it to the foundation, what else could I do to minimize potential damage?

If your home was built in 1911, then you know it survived at least three quakes - in 1949, 1965 and the 2001 Nisqually quake. That's a good sign. But those quakes were all relatively small compared to a coastal megaquake. Bolt the house to the foundation, get rid of hanging hazards and hope for the best! (As to the stability of your slope, you could consult maps of landslide prone areas in Seattle, which are available online.) Sandi Doughton

Is the city of Seattle working on having an emergency plan?

Yes, there are several plans in place and in development, including a Mitigation Plan, a Recovery Framework. Here is a web link for the City's plans: http://www.seattle.gov/emergency-management/what-if/plans

Also, Seattle did extensive work as part of a Regional Catastrophic Planning Effort. All of those plans are on the State of Washington's web page: http://mil.wa.gov/other-links/plans

Hope these help. --Debbie

What about seiches in the lakes in the Seattle area? What damage is expected from sloshing in the lakes?

For seiche and sloshing, expect damage to mooring lines and utilities. Water damage and flooding to the surrounding area can also occur. Houseboat residents and boaters, however, often have back-up power systems, and some can generate their own drinking water. -Debbie

What is the likely hood of after shock earthquakes? will they be as sever as the original? Will they trigger another Tsunami?

An M9 earthquake is likely, on average, to have about an M8 aftershock, and quite a few M7s. They might make waves, but the M9 wave would be the monster. - John

After a coastal megaquake, aftershocks will continue for a very long time- possibly years. Some can be very big - but not as big as the main shock. And over time, they tend to diminish in intensity. However, if only a portion of the offshore fault ruptures, it's possible that could ratchet up the pressure on the rest of the fault and another major quake could occur soon after. That happened after the quake that spawned the Indian Ocean tsunami in 2004. Sandi Doughton

Currently living in Downtown Edmonds, Wa just a block away from the beach. Could Edmonds be hit by a tsunami generated by Seattle fault?

Yes, it could. The last known quake on the Seattle Fault occurred about 1,100 years ago, and evidence of the tsunami was unearthed at West Point, in Seattle (Magnolia) and also on the south end of Whidbey Island. Washington DNR has created maps of areas likely to be flooded by a Seattle fault tsunami - you can find them on the web.

Sandi Doughton

What is the likelihood of a significant Seattle Fault earthquake? How bad would it be?

The last Seattle Fault quake was about 1,100 years ago. Geologists don't really have a good handle on its recurrence period, but estimates range between 1,000-5,000 years. Not that helpful. The best rule of thumb I heard from a USGS expert is this: Given the large number of shallow faults in the Puget Sound region, it's probably reasonable to expect a quake on one of them every 1,000 years or so. The top magnitude for a Seattle Fault quake is about 7.5. Sandi Doughton

Wowza! I am still recovering from reading the New Yorker article. I currently live 458 feet above sea level in the West Seattle area. Am I relatively safe from a tsunami?

Also, are there any good website out there that will allow citizens to enter in an address and see what would happen if the water rose to tsunami-like levels?

I live in West Seattle, too. You've got nothing to worry about from a tsunami - even a tsunami from a quake on the Seattle Fault. The tsunami from a coastal megaquake will be insignificant in Puget Sound. Washington DNR has developed an excellent series of tsunami inundation maps, you can find on their website. Sandi Doughton

Will the Earthquake reach places like Redmond, Bellevue, and Kirkland? If so, will it be very severe?

Yes, the shaking from a coastal megaquake will be felt in all those areas. We also have shallow faults in the Puget Sound region that can generate local quakes that can be very damaging. For the M9 megaquake, the shaking on the east side of Lake Washington won't be bone-rattling, but it will go on for a very long time- perhaps 5 minutes or more. For a quake on a local fault the shaking can be much stronger and more intense. Sandi Doughton

The initial shaking will be short, sharp and choppy, but then the ground will start to feel like it's rolling, like the sea. The main difference between an M9 quake and smaller quakes is that the shaking will feel like it's going on forever - five minutes or more. Most quakes only last about 20-40 seconds. Sandi Doughton

What is the expected timeline for this huge event?

Timeline during the event, or leading up to the event? - John

How big on the Richter scale are you anticipating?

We'd use the moment magnitude scale, the richter scale saturates, but that is a detail. The 1700 quake was somewhere between an M8.8 and an M9.1, and that is our best guess what the next one will be as well. - John

I was hoping to move to PNW. Some day. If my husband got a good job offer. If I were your favorite cousin, would you tell me not to do this?

Absolutely not - the PNW is one of the most beautiful parts of the country! Do your due diligence to prepare, know the reality, and then enjoy your life. Earthquakes will happen, yes, the big one, yes. But there are hazards everywhere. I love it here. -Debbie

I'm on mobile & quoting from memory but I recall there was a bit about a concussion wave that rolls out immediately prior to an earthquake that can serve as an early warning system now in Japan. I think it was about 30 seconds warning, during which time things like mass transit & electrical grids can be shut down. I understand that can be the difference between disaster or extinction, but is that as much early warning as we'll ever have? Is there more science being done on this specific seismological issue?

The first warning comes from the small, fastest P waves, the strong shaking is delivered by the slower S and surface waves. The warning time depends how far away is the earthquake from the place to be warned. Warnings range from 1 to 3 seconds per 10 km distance from the start of the quake. Since the M9 can start 500 miles away, several minutes of warning are possible. - John

1. What states will this earthquake affect?
2. When is it estimated to hit?
3. How damaging will it be?

This quake would span Oregon, Washington, and parts of California and Vancouver Island. It will hit sometime in the next 500 years. Estimating the damage is complex and uncertain - the cost is estimated to be between 50 and 150 billion dollars, just to give rough numbers. - John

Thanks for doing this AMA! This may not be a question you feel qualified to answer, but what's your opinion on earthquake retrofitting older wooden houses (securing house to foundation)? Worth the effort, or close to useless?

Definitely worth it. We want and need most people to be able to stay in their homes after a large earthquake. Having your home bolted to the foundation is a good way to increase the chance that you can. We offer seismic home retrofit classes throughout the year (free), so people can learn more about the process and become educated consumers when having the work done. -Debbie

Okay, so we've established that Seattle is basically safe from a tsunami from "the big one." What about Portland and Olympia? Are only the coastal towns like Astoria really in danger for tsunami risk during "the big one"?

Yes, far and way the main risk from the tsunami will be along the outer coast. It will also travel down the Strait of Juan de Fuca, and could do damage in Port Townsend and on the west side of Whidbey Island. It will travel some distance up the Columbia, too. For those of us who live inland - even Portland - the main thing to be concerned about is the shaking and how long it will last. Sandi Doughton

What impact, if any, will there be along the fault lines that run west-east through Puget Sound during The Really Big One?

Big earthquakes can trigger more events on nearby faults, so a quake on the Seattle or the South Whidbey Island fault is possible during or shortly after a great earthquake on the coast, but again, the biggest problem is most likely to be the shaking from the great quake. - John

Does the tsunami threat increase or decrease as you go up further north (Bellingham - Vancouver BC region)?

I think the threat is fairly even from mid-Vancouver Island down to California, but diminished into the Strait of Juan de Fuca, and isn't so much in Bellingham and Vancouver. More local earthquakes might be a threat to those inland cities. - John

Which infrastructure projects are state/local governments currently working on to protect the Seattle region in the eventuality of an earthquake? Which improvements will be key in ensuring that the region rebounds relatively quickly?

In 2010, we published a 10-year Post-Nisqually summary of efforts completed by all City departments. These included: retrofit or rebuild of every city fire station, hardening of fire hydrants, retrofiting the North Queen Anne Drive bridges, Post-Alley and King Street Station. We placed generators in several community centers and established emergency supply caches in four areas of the city. See the full report here: http://www.seattle.gov/emergency-management/what-if/hazards/earthquake

-Debbie