Getting ready for the Big One
The images of the quake aftermath in China raise the question: What would the wake of a major quake look like in Seattle? Fortunately, we have the answer. Or at least a pretty good guess.
Events in China have nudged earthquakes closer to the top of our minds. Here in Seattle Mayor Greg Nickels is calling for seismic retrofitting of nearly 1,000 of the city's older brick buildings, which are at risk in the event of a major quake. Seeing the devastation in southwestern China, it's hard not to wonder what could happen here. We're told, a major quake is just a matter of time. How would we fare? And what would the aftermath look like?
We've done our homework. In 2005, the Earthquake Engineering Research Institute, an Oakland, Calif., non-profit group, conducted an extensive study of what would happen if Seattle were hit with a 6.7 quake on the Seattle Fault, which runs roughly from Hood Canal to Issaquah and right through Seattle. The so-called "Seattle Scenario" [38.2 MB PDF] is chilling. The quake in China was 7.8 on the Richter scale, but the projected Seattle one is smaller, comparable to the Nisqually quake (6.8) of 2001. Unlike Nisqually, however, it would be right under our feet.
Even so, the projected losses are appalling: With $33 billion (that's on the low side) in losses, there would be 1,600 dead and 24,000 injured, and 9,700 buildings and homes would be completely destroyed, 29,000 rendered unsafe for use, and 154,000 suffering moderate damage. The quake would collapse bridges, shut down highways for weeks or months, and cause more than 1,000 landslides, some of which, in turn, could cause mini, localized tsunamis.
The Nickels plan is based on a 6.7 scenario, too. According to The Seattle Times, last year "engineers looked at 575 buildings from the outside and estimated 850 to 1,000 such buildings in the city would be at risk if a 6.7-magnitude earthquake occurred on the Seattle Fault ..." Retrofitting them all would cost $358 million to $431 million, according to the Times. Most were built in the 1930s and earlier, and they cluster in neighborhoods like Ballard, the University District, First Hill, Capitol Hill, the waterfront, Pioneer Square, and the International District. The southernmost neighborhoods would likely be the hardest hit in the Seattle Scenario because they're closer to the epicenter and because of soil conditions. (Here's a look at local earthquake hazard zones.)
But they aren't the only structures at risk. Many modern, concrete buildings, such as the boxy factories and warehouses in SoDo or retail and manufacturing sprawl zones like the Kent Valley, are also likely to topple. And, according the the scenario's numbers, even if all 1,000 Seattle brick structures were retrofitted and didn't collapse, another 8,700 building of various kinds would be destroyed, either in the quake or the aftermath (landslides, floods, fires). In other words, retrofitting is common sense, but there's no panacea, and even the mayor's proposal doesn't cover all the buildings that need retrofitting.
A 6.7 quake in Seattle would severely damage and hamper our transportation infrastructure, according to estimates. Since disasters are commonly used these days to prod people to fix the Alaskan Way Viaduct and replace the 520 bridge, it is worth noting that while building stronger roadways might be ideal, given our locale and geography, nothing we do will make us entirely earthquake-proof.
Another thing the scenario looks at is disaster recovery time: Economic losses are largely determined by how fast a damaged, modern city (Los Angeles, San Francisco, and Kobe, Japan) can get back on its feet. One of the most expensive earthquake disasters in this respect was the 1994 Northridge quake in Southern California, but the Seattle Scenario's authors point out that recovery there was quicker than what Seattle could expect because the Los Angeles freeway system has a lot of redundancy. We have comparatively few freeways, and alternative surface routes would likely be jammed, if not heavily damaged and clogged with debris themselves. In other words, our current grid is not designed to make it easy for us to bounce back. That suggests that instead of simply making new structures stronger, we should eye improvements that could quicken recovery.
Some lessons have been learned. The trend of replacing old brick schools with newer ones, or retrofitting and remodeling older buildings to bring them up to safer seismic standards, is working. During the Nisqually quake, schools were pretty safe places to be, unlike in China, where many schools suffered catastrophic collapse. Making progress a bit at a time can pay dividends when the "big one" hits.
One problem with the mandatory retrofitting of Seattle's old privately owned brick buildings is moving carefully so as not to make matters worse by requiring property owners to suddenly shell out money they don't have. That could lead some owners to decide to tear down or close down perfectly useable, important, and possibly historic structures.
Mandatory upgrades would have to come with incentives and assistance, like low-interest loans, the waiving of permit fees, tax breaks and credits, etc. Even then, however, it will be a tough sell. The Seattle Scenario found that even in quake-prone greater Los Angeles, public and private infrastructure upgrades were sometimes slow to be adopted.
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Comments:
Posted Mon, May 19, 9:55 a.m. inappropriate
Getting back on our feet: Thanks for this timely look at the key planning need in our area.
Of the many components, all of them important, one planning element that constantly surfaces for me is captured in this sentence: "Economic losses are largely determined by how fast a damaged, modern city (...) can get back on its feet."
In the dire emergency conditions that would result from this Seattle Fault earthquake, getting back on our feet will become the most important consideration after initial rescue, stabilization, and public shelter questions are decided. Factors in this performance will include the the infrastructure, organization, cooperation, and agreements between nearby cities and among nearby companies.
What is the current state of affairs of these relationships? How would our region work together (or not) to again stand up in the world community?
Posted Mon, May 19, 1:15 p.m. inappropriate
Settle-centric Assessment of Potential Quake Impacts: Interesting that Knute would write such a narrow piece on quake preparedness. Here on Vashon Island, emergency preparedness leaders decided after the Nisqually quake that the Island better get prepared not only for the physical impacts of such a quake but also extended isolation and lack of food and shelter and medical assistance if our ferry transportation went kaput. Vashon Be Prepared is a really good community example of what folks can do when focused on such a potential problem.
Posted Mon, May 19, 2:33 p.m. inappropriate
close, but not quite: If Knute had read the Seattle PI article in addition to the Times article, perhaps he would have refrained from making the common and highly misleading mistake of comparing the magnitude of a 6.8 deep quake (like Nisqually) to a 6.8 Seattle Fault quake. They are not apples and apples. The Seattle Fault is a shallow fault, like the one that produced the quake in Sichuan Province. The Nisqually Quake came from a deep fault. Even if Nisqually had occurred under Seattle, it still would not have been a big quake. It is the nature of the ground motion shaking that matters, not so much the magnitude.
Posted Mon, May 19, 2:56 p.m. inappropriate
RE: close, but not quite: Fair point. I encourage people to read the specifics of the "Seattle Scenario" because there are all kinds of assumptions about the quake (where it occurs, etc.) that go into making up the hypothetical. The magnitude does not tell the full story. I should note too that it is not the worst-case scenario by any means.
Posted Mon, May 19, 7:43 p.m. inappropriate
We will all be on our own, and we'd better get used to that.
Experts in the field used to advise individuals to prepare for three-days of self-sufficiency. Since Katrina, that's been upped to seven. Advance planning for food and water, shelter, communication, and other necessary services needs to be done by every citizen.
And not just in your home. What happens if it strikes while you're on the road or in the office? Stockpiling supplies in your car and place of work - actually, any place you spend a lot of time (Blue Moon, Mossback?) is necessary too.
Anyone who hasn't should consider Community Emergency Response Team or C.E.R.T. training under the auspices of your local fire department. You will learn stuff that will turn your "instincts" on their head. Plus you get a neat green vest and hard hat so you can look official.
But the preparation and training is well worth the investment in time and money since once it happens, it will be too late to give it further thought.
I remember the Anchorage quake back in the 60's, and one that size - it would make the 2001 Nisqually quake look like a piker in comparison - could hit us. In that event, there would be a lot more pressing public health and safety priorities than bailing my hind end out of trouble - Mossback's, too, for that matter, despite his iconic status as the town resident curmudgeon.
Don't forget the mess of last winter's floods and the windstorm of the year before. You have to wonder whether we're being sent a message to get ready for something worse - way worse.
In a nanny state like Washington, our reflex instinct is to look first to the gub'mint to solve our problems. Too bad that it will take a serious natural disaster to knock that stuffing out of us.
We are each responsible for ourselves. Everyone out there prepared?
The Piper
Posted Tue, May 20, 9:33 a.m. inappropriate
the liquefication: that will occur in SoDo and other landfill areas [U-Village, to Lake Washington] might be emphasized. I happened to experience the Northridge earthquake [4 AM I recall] while living appr. 12 crow miles off in Venice, CA. in 1994; Venice is built on landfill which would have liquefied. Nonetheless, a lot of brick buildings along the Boardwalk and in St. Monica were heavily damaged; and a lot of t.v. sets fell of their pedestals!