What does it mean to build a disaster-resistant community? It means raising citizen awareness of the dangers we face, the importance of preparing for disaster, knowledge of how to respond, and insisting that our elected officials do what they can to create a disaster-resistant infrastructure (e.g. building disaster-resistant fire stations and schools – which can serve as emergency shelters – in every community in our city, beefing up seismic building codes, etc.)
A prepared citizenry is the most important component of a disaster-resistant community! One need look no further than New Orleans in the wake of hurricane Katrina to see the effect an unprepared citizenry. Wholesale reliance on government to prepare for (or respond to) disaster can be a fatal mistake. Government planning is critical, but citizen preparation is essential. If every citizen is prepared to deal with disaster, our community will fare far better than if we rely on government alone.
It is important to understand that as bad as Katrina was, the devastation of a Cascadia subduction zone earthquake will be far, far worse. It will affect 84,000 square miles of the Pacific Northwest! “Don’t be scared, be prepared” is Alaska’s emergency preparedness motto. Wise words. It should be our motto too. We need to start planning and preparing now, today. Every one of us. Individual citizen, school principal, business owner, elected official, government agency, all of us.
|Fire stations are critical to every community. They house our emergency responders: Emergency medical technicians and fire fighters. And schools house our future, including our future EMT’s and fire fighters. Shouldn’t both of these facilities be as disaster-resistant as possible?|
Currently, Portland's seismic codes are too lax (and give us a false sense of security). And certain big-money interests would like to keep things that way. Ironically, the most seismically resilient design, a monolithic dome, is more economical than conventional box-shaped buildings. It seems criminal to build critical facilities like fire stations and schools to lower standards when monolithic dome technology is so disaster-resistant, energy efficient and cost effective. Isn’t it time the taxpayer got their money’s worth for a change?
Not long ago an article ran in a local paper, citing a PSU professor of urban studies, which suggested Portland was pretty disaster-resistant because we’re retrofitting fire stations to meet seismic code. Another article quoted an engineer saying that the fault lines running through Portland only produced large earthquakes every 6,500 years or so. Both sounded reassuring, and both had a kernel of truth. However neither told the whole truth, and the devil, as they say, is in the details.
The fault lines running through Portland are not the ones which are of greatest threat to Portland. The Cascadia subduction zone a hundred or so miles from Portland is the one we need to worry about the most. It regularly produces M9+ megathrust earthquakes every 300 years or so. (The last one occurred more than 300 years ago, on January 26, 1700.) And when it slips, the entire land mass between the Cascade mountains and the Pacific Ocean, from southern Canada to northern California, will be in motion for up to five minutes. And the shaking will be more than a thousand times more powerful than the M7.1 Loma Prieta (aka “World Series”) earthquake which – a hundred miles from its epicenter – collapsed a freeway, a span of the Bay Bridge, and wreaked havoc in San Francisco’s Marina District.
Okay, so maybe we can expect a really big earthquake soon, but at least we’re retrofitting fire stations and bridges to meet seismic code, right? Technically, yes… however that is not the whole story. Portland’s zone 3 seismic code standards anticipate an earthquake about the size of the Loma Prieta quake. They are weaker than California’s zone 4 standards. Even zone 4 standards aren’t intended to withstand a sustained M9+ event (like Cascadia). Only Japan and Chile are building to withstand such great quakes. Furthermore, seismic standards are intended only to prevent total collapse, thus protecting lives; the building may not be safe or usable afterward. But for earthquakes larger or longer than the seismic code zone anticipates, total collapse may occur. So a school or fire station built to meet Portland’s seismic code has no assurances it will remain standing nor protect life, much less remain functional and safe, after a Cascadia subduction zone megathrust earthquake… an earthquake at least 1000 times more energetic than what we're building to withstand.
So why are our seismic codes so lax? Two reasons: 1) It is only in recent years we have come to understand the severity of the earthquake threat we face here in the Pacific Northwest, and 2) Money. In general, stronger seismic standards mean higher building costs. And that often leads to political push-back from developers. However there are economical ways to build stronger, if you think outside the box… literally.
Conventional buildings contain many joints between walls, roof & foundation. During an earthquake these joints, called “moment connections,” are subjected to enormous stresses. If the stress is great enough or prolonged enough, the joint fails and the building collapses. Creating stronger joints can rapidly escalate construction costs, yet failure of the joint is still possible. A better and more economical approach is to reduce the number of moment connections in a building. A building without any would distribute seismic loads evenly across the entire structure. A thin-shelled one-piece (i.e. monolithic) dome made of steel- & fiber-reinforced concrete would have few, if any, consequential moment connections an earthquake could damage. This type of building has by far the best chance of surviving Portland’s greatest seismic threat. Amazingly, a large monolithic dome structure is less costly to build, heat or maintain than similar sized conventional structures.