Minamisanriku, Japan, after the M9.0 earthquake and tsunami in 2011 source: Richard Eisner
If you live in the Pacific Northwest, you should prepare for a large earthquake.
I say this not because I know we will get a large earthquake in the near future, although that’s a notable possibility. Even a probability.
My main reason for saying this is that preparing for an earthquake covers all sorts of disruptive events that are seeming more likely and more imminent.
Consider the likely aftermath of a Cascadia Megaquake, concluded in the 2013 Oregon Resilience Plan:
These are not minor implications. Imagine being 1 to 12 months without clean and available drinking water, and 1 to 3 months without reliable electricity. Something like this will happen. It’s just a matter of time.
But back to my original point. Other disastrous events seem more likely than they used to be. I’ll name a few.
Natural disasters such as wildfires.
Civil unrest. Our nation is becoming more divided than ever, at least in modern history. And the last few years have not helped.
Economic collapse of some sort.The United States and other nations have been on an unsustainable spending spree for decades, but especially the last 15 years or so. The last few years have not helped on this front, either. It’s not going to end well.
I could go on. Global tensions are higher. Russia and Ukraine are currently at war. We are not guaranteed peace in North America.
I do not believe in spreading irrational fear (and I’m not). I suspect you feel it, too. I want to help save lives and help us to prosper as we move into an uncertain future.
The February 2023 earthquake in Turkey and Syria reminded us of how fragile the world is. Source: EERI
Chris Goldfinger went on record with a calculation that there is about a 1 in 3 chance of a Magnitude 8 or higher earthquake off the coast of Oregon in the next 50 years (See “The Really Big One” New Yorker article).
Let us assume that estimate of probability is accurate. Consider what kind of odds we have of any significant disruptive event in the next 50 years- say, a regional, national, or global event, but one that affects us in our location. They’re high… very high.
Many other disruptive events could have similar effects on life and infrastructure in the Pacific Northwest as a large earthquake.
I’ll throw something else out here for consideration. I noticed after the December 2022 M6.4 Ferndale earthquake in northern California, Temblor (an earthquake risk assessment and catastrophe modeling company based in the Bay Area) had this to say: “The (Ferndale) quake produced severe shaking in a lightly populated area, (and) brought the southern tip of the Cascadia Subduction Zone slightly closer to failure…”
Tectonic action is often happening beneath us and off the coast that remind us that the Cascadia Subduction Zone is indeed active, and a large earthquake is looming. The Ferndale earthquake was a recent reminder.
Damage to Molalla High School after the 1993 M5.6 Scotts Mills Earthquake, about 20 miles south of Portland, Oregon
Priorities?
There are many good personal and family goals worthy to be pursued, so earthquake preparedness does not always seem like it needs to be an urgent priority. In addition, our exceedingly distracting world does not help us achieve goals, in general.
Please consider putting earthquake preparedness at or near the top of your list. Or, if you don’t live in earthquake country, preparedness for a particular event that aligns with your region. I would argue that some things we are often encouraged to prioritize should go below earthquake preparedness.
The point of this post is not to get into preparedness details, but think of food, water, sanitation, personal fitness, etc. It’s a time-consuming endeavor and probably needs to be thought of more as a lifestyle change than a checklist of things to get done. A perk about preparedness is that it can overlap with activities that we tend to value in the Pacific Northwest: camping, biking, gardening, hunting, etc.
For information about seismic assessments or retrofitting of a home or building, please see the Cascadia Risk Solutions website.
Whether or not the big earthquake happens in the near future, now is the time to prepare for it.
One of the top priorities in preparing for an earthquake is making sure your home is safe.
Many homeowners in the Pacific Northwest are concerned about how their home will perform in a large earthquake, but they are confused. Some think earthquake insurance is the next step, but haven’t thought much beyond that. Others (wisely) have considered earthquake retrofitting. But that opens the door to all sorts of questions, like:
How do I verify that the retrofit will actually be effective?
Does my house go from bad to awesome in terms of earthquake performance, or bad to okay, after the retrofit?
Is my house okay without any seismic strengthening?
What else should I do besides the retrofit? What do I need to do myself?
House with failed cripple wall- South Napa earthquake, 2014
My goal is to provide as much useful, free information as possible, and shed some light on a confusing topic.
Earthquake Vulnerabilities are no Mystery
Although earthquake awareness has increased much in the Pacific Northwest, many people are so overwhelmed by the thought of it that some make statements like this:
“There’s no way we can know what will happen to our house after a 9.0 earthquake”- Typical pessimist’s home earthquake risk assessment
While it’s true that we can’t know for sure what will happen, we can make good estimates based on past earthquake data and engineering principles. Plenty of helpful information is out there, and it’s available to those of us who have searched for it and used it in our work. I’d like it to be more available to the general public, which is why I’m writing this.
I’ve been amazed at the wealth of information available at sources such as FEMA or various earthquake engineers I’ve spoken to in California who have designed earthquake strengthening measures for buildings and then seen them tested with actual earthquakes.
Methodologies to assess earthquake risk have been in development for decades, and are based on actual earthquake damage to various building types.
FEMA’s P-50 (for houses) and P-58 (for various building types) methodologies are very helpful resources for assessing earthquake risk, and in my opinion, their usage needs to be marketed more to home and property owners. I use both methodologies as well as structural engineering principles.
The vulnerabilities that cause damage to homes in earthquakes are well documented, but not easily accessible to the typical homeowner in the Pacific Northwest. So… what are they?
One simple way to categorize the different variables affecting any individual building’s earthquake risk are below-ground and above-ground variables.
Below-Ground Variables
The below-ground variables are the geological site characteristics, such as the distance from the earthquake source and the soil type. Ground shaking will generally increase the closer you are to the earthquake source. This is common sense.
What many don’t know is the effect that soil type can have on ground accelerations. In the 1989 earthquake in San Francisco, for example, ground shaking was five times stronger at the Fisherman’s Wharf area (with soft, saturated soil) compared to the Chinatown area, which is on bedrock and only a half mile away.
In some cases, a site that a house (or any structure) is built on can be so poor that a seismic upgrade is not even worth considering, at least, from an economic perspective. The only reasonable choice for a homeowner in this scenario may be to either move away or simply live with the risk.
Near collapse of a “weak story” building on soft soil after the 1989 Loma Prieta earthquake in San Francisco. There are many buildings in Portland and Seattle that have both of these vulnerabilities.
Other below-ground hazards include liquefaction and lateral spreading, which tend to occur in sandy, saturated soils in low-lying areas, and landslides in the hills. I also include tsunami risk in this category; although it’s technically not below the ground, it’s a feature unique to the site where a building is located.
With our abundance of water in the Northwest, and the potential for an earthquake shaking 3 to 5 minutes, geological hazards pose a great risk in many areas.
There are helpful free online resources to allow home or building owners to quickly assess their geological hazards. For example, the Oregon Department of Geology and Mineral Industries has an interactive map where all of these different site hazards can be viewed for any location in Oregon (the mapping is on a macro level and does not eliminate the need for a site geotechnical investigation, but is still helpful information). OPB’s “Aftershock” tool combines ground shaking, distance from the Cascadia Subduction Zone and soil type to give you a qualitative explanation of what to expect at your specific address.
These tools, however, are not building-specific, and for this reason, they do not accurately quantify the earthquake risk of your home. They are helpful tools- and I recommend using them- but there will be a huge variability in earthquake damage from one home to another, even in the same neighborhood, because of the differing construction of each home.
Above-Ground Variables
Above the ground, every structure will respond differently in an earthquake. Every home has its unique geometry and construction, which will affect the way it reacts to the forces.
There are plenty of exceptions, but in general, newer homes perform better than older homes.
A building will shake roughly proportional to its weight and height, which means that a smaller one-story house will typically do better than a larger two or three-story house.
Wood-framed houses tend to perform well in earthquakes, if they don’t have any significant vulnerabilities. Wood-framed construction is flexible, which dampens earthquake forces. This is true even with older wood-framed homes, although damage is typically greater. This is one reason why a brick house would likely perform worse than a wood-framed house in the same neighborhood.
The following common above-ground vulnerabilities tend to generate earthquake damage:
Brick Chimneys. Chimneys are heavy, tall, skinny, and brittle. This is a dangerous recipe. Even in moderate earthquakes, chimney damage is common and can result in injury or death.
Weak Cripple Wall. A “cripple wall” is the wood-framed wall between the home’s foundation and its first floor. A house with an elevated porch often has a cripple wall, particularly if there is no basement. This is a common weakness in older homes, and failure to strengthen a cripple wall can result in the house suddenly dropping and shifting laterally a few feet during an earthquake. This usually results in a complete economic loss of the home.
Inadequate Foundation Anchorage. In hindsight, it’s amazing that builders didn’t think it was necessary to attach wood-framed houses to the concrete basement walls or foundations way back when, but that’s how they commonly built homes. It’s also amazing that many relatively new homes sometimes have inadequate anchorage, even homes built after the building codes required it. The code began catching up to our knowledge of a potential large subduction earthquake about 20 years ago, but I sometimes see homes built as late as the early 2000’s with missing nuts and plate washers on many of the anchor bolts. Inadequate anchorage is a common failure mechanism in earthquakes which results typically in total economic loss as the house slides off the foundation during strong shaking.
Deteriorating concrete or brick basement walls and foundations. This is a common structural problem with homes around 100 years old in Portland. It’s a hazard that should be addressed regardless of earthquake risk. It’s also important to not attempt a textbook retrofit that attaches to poor concrete or brick without an expert’s input.
Soft or Weak Story homes. A practical definition of a “soft story” is an exterior wall line that has very few wall segments (i.e. it is mostly composed of windows or openings). A common example of this is a garage door with a living space above it and very little wall width each side of the garage door. The narrower the walls each side of the garage door, the greater the likelihood of severe damage. Another similar issue with older homes is that after a century of different owners, the current floor plan is open with more windows and less walls than it originally had. If enough wall segments are removed, very little lateral strength remains. A weak story combined with liquefaction-prone soil is particularly dangerous in earthquakes.
Hillside Homes. By far the most dangerous demographic, these homes can suffer severe damage during an earthquake. Not only is the structure often weak and top-heavy, as in the case of homes on “stilts”, but they can have catastrophic landslide risk. They also often have other structural problems such as torsional weakness and lack of ductility with bracing or shear walls.
Split Level Homes, Complex Floor Plans and Roof Lines. Complexities to homes add character, but sometimes they are problematic for an earthquake load path. The more discontinuities in roof, floor, or wall lines, the more likely separations will occur.
Elevated Porches and Decks. These types of “add-ons” to a house sometimes detach from the house during an earthquake and collapse without adequate bracing.
The remnants of two hillside homes after the 1994 Northridge earthquake in the Los Angeles area.
In the past decade or two, a number of contractors have established a niche for residential earthquake retrofitting. Typically, an earthquake retrofit contractor will provide services primarily relating to weak cripple walls and inadequate foundation anchorage. Rightly so, because these vulnerabilities are common and relatively inexpensive to fix compared to say, a home on stilts or with a severe soft story problem. But as I’ve established, there are many variables of earthquake risk both with the site of a home and the structure itself, and these risks aren’t always communicated or addressed.
Bracing For Cascadia
Many people have latched onto phrases like, “everything west of I-5 is toast” (a quote made somewhat infamous after the 2015 New Yorker article, “The Really Big One”), and they envision a post-earthquake Northwest where all or most buildings are destroyed. Some suppose the tsunami will enter the Willamette Valley and Portland. Neither of these ideas are true whatsoever (and that’s not what the quote meant). I expect most buildings to remain standing after our big earthquake. I expect most homes to do even better than other buildings overall, as they have done in past earthquakes.
That’s not to say the earthquake won’t be a major disaster. It will certainly be. Power outages for 1 to 3 months in the Portland area, which is what the state expects, is a disaster.
As far as home preparedness goes, we need a realistic view of our earthquake risks. We need to make sure we don’t have a home that is prone to damage. We want to ride through the earthquake uninjured if possible, so we can help others. And as most of us know, there are numerous other tasks we need to do to prepare for the earthquake, so let’s make sure our homes are safe to the best of our ability.
For more information about seismic risk assessments and retrofitting, please see the Cascadia Risk Solutions website.
Most structural engineers have experienced a glazed-over look in someone else’s eyes when describing what they do for a living, followed by a response like, “so, you’re an architect?”
There remains ignorance in the public about what structural engineering (and engineering in general) is for. Other engineering disciplines may be even more confusing; I doubt most people could define the term, “geotechnical”. Personally, I’m still not 100 percent sure what an industrial engineer does.
I think the fault of this ignorance lies primarily with engineers. We have an incredibly cool profession and if people understood better what we do, we would probably make more money, quite frankly. Especially if we were passionate about taking our skills and orienting them toward serving the community, region, and world to make it a better place (which is the reason all professions should exist).
Structural engineering seems to be making more inroads into the public sphere in recent years. It’s always amusing when Hollywood addresses your career. This happened in the latest Star Wars movie, Rogue One (slight spoiler alert if you haven’t seen it). The movie specified a large building, which reminded me of a dark version of a Dubai hotel, as a site dedicated to structural engineering (among other things) for the Empire. And there was also the scene of a group of engineers (in lab coats?) being assassinated for apparent faulty design of the Death Star. Considering the fact that this Death Star weakness led to the downfall of the Empire in subsequent episodes, this was understandable using Imperial logic, I suppose.
The Structural Engineers Association of Oregon has this clear statement defining the profession of structural engineering (good job, whoever wrote it):
Structural Engineering is the practice of analyzing and designing buildings, bridges and other structures to resist forces induced by gravity, wind, and earthquakes and to safely transfer these forces to the ground.
See here for more: http://www.seao.org/resources/aboutstructengr/
Regarding engineering in general, there are a number of good definitions online, but here is my very simple one:
Engineers apply science and mathematics to the real world to solve real world problems.
Engineers and the engineering profession should act as a bridge between the theoretical realm of science/ mathematics and real life.
Consider the large problem of an impending Cascadia megaquake. The science indicating that these earthquakes have happened and that the subduction zone is locked and building up energy has been settled for about 20 years.
Emergency management at the state and federal level has been aware of the threat for a long time also. The Oregon Resilience Plan, which was a state funded plan addressing the effects of a Cascadia megaquake and its consequences, was published in 2013.
Journalists helped disperse the information about this topic into the homes and hearts of Pacific Northwest residents (thank you Sandi Doughton and Kathryn Schulz, to name two). For the last couple of years, there has been more mainstream awareness of this issue than ever. And my experience has been that people are still baffled by the topic and wondering what to do about it.
Here is my exhortation to engineers, particularly those involved in the disciplines of infrastructure (civil, structural, and geotechnical at the forefront). The Cascadia earthquake threat is large enough to involve all of our individual efforts for years. Please consider what part you can play in increasing your personal, community, and regional resilience. We all know more than the average person about earthquakes and what they do to the ground and to structures. Don’t hide in your cubicle or office. Do what you can with your career to help and you will be saving lives when the earthquake happens.
In Portland, engineers know that there are about 1800 URM (brick) buildings which may partially or completely collapse in a large earthquake. We know many older homes have weak cripple walls, dangerous unreinforced chimneys, and “soft story” weaknesses which will result in damage, injury, and in some cases, loss of life. We know there will likely be long term loss of power and drinking water. We know industrial areas are set to contaminate our rivers with millions of gallons of liquid fuel. Wow, that’s just the tip of the iceberg. Let’s get to work.
Engineers are a key to helping bridge our gap between what we now know (the science) and resilience. But not just engineers… every one of us can help and I would argue that we have a duty to make steps toward preparedness.
The reality of a potential impending large earthquake in the Pacific Northwest has made its way to the general public in the last few years. When the New Yorker article “The Really Big One” came out in the summer of 2015, many of us were shocked and genuinely scared. After some initial shock wore off, people reacted in a number of ways ranging from buying earthquake insurance to storing up food and water to just living with a new level of anxiety they hadn’t known before (the latter probably being the most common reaction). I recall talking to an insurance agent soon afterward and he told me that it was crazy how many people had rushed to buy earthquake insurance recently. He didn’t miss a beat transitioning to sales mode in his next statement, which was something like, “you should consider buying some also to protect your family.”
But what should we actually do with this information that is new to many of us? And, to address the title of this blog post, how do we deal with “earthquake anxiety”?
Consider this goofy story as an anxiety illustration: I was recently in a restroom at Starbucks and the lock on the door didn’t give me any evidence that it worked. This mattered because the door opened to a view of the coffee line and cash register. I played with the lock and couldn’t gain any confidence in it. It made almost no sound when I pressed it, and it didn’t seem to even change position. Opening and closing the door a couple of times didn’t verify it’s functionality, except for a small, barely audible click. I reluctantly used the restroom anyway, but not without some anxiety.
That’s already too much information with the personal restroom story. But here’s the point about anxiety: it is caused by feeling like you have no control over a potential problem. The solution, I believe, is a combination of taking purposeful action that addresses the problem and letting go of control over the things you don’t have control over.
Consider how much lower my anxiety in the restroom would have been if the door had a deadbolt that made a loud noise as it was being engaged and it visibly could be seen sliding into place through the crack in the door. In the same way, adequate earthquake preparedness steps give you confidence that you have addressed the problem and will likely survive “the really big one”, and even thrive in the aftermath and be able to help others.
I just mentioned that the solution to earthquake anxiety is to take purposeful action that addresses the problem and to let go of control over things you don’t have control over. The first step involves practical actions, many of which could be accomplished by anyone living in the Pacific Northwest. The second is more related to mental health, psychology, etc, which I’m not an expert on (but see Matthew 6:25-34 if you are inclined as I am to address this through the lens of faith).
I will dive into some specifics in further posts, mainly related to actions we can take, but for now I want to point out that we can only do what we can do. We can’t control when an earthquake (or any future high stress event) will come, but we can make a huge difference in our resilience when it does. A head-in-the-sand approach is irrational and will not make anxiety go away. Also, resigning to the overwhelm of tasks ahead is not a good approach, either: “I’m not going to do anything because there would be too much to do”, or “it will happen if it happens” are examples of this kind of thinking.
The work ahead in earthquake resilience can indeed be overwhelming, but even just a first few steps can make a big difference on an individual or family level than not being prepared at all. A good preparedness plan will add redundancy to whatever plans you put in place. This is a topic, that, if you plan to live in the northwest for a long time, is very important. What should your next steps be in 2017 to make yourself and your family more earthquake resilient? If you have no ideas, stay tuned here…
