Every 300 to 500 years the Juan de Fuca tectonic plate lurches under the overlying North American plate, triggering a massive, magnitude 8 or 9 earthquake. The last of these “megaquakes”—known as Cascadia Subduction Zone (CSZ) earthquakes—occurred about 300 years ago.
In other words, prepare thyself.
A comprehensive analysis of the Cascadia Subduction Zone conducted by Chris Goldfinger, director of the Active Tectonics and Seafloor Mapping Lab at Oregon State University, concluded that there is up to a 40 percent chance that a magnitude 8 or above earthquake will strike off the coast of Oregon within the next 50 years.
It will be catastrophic.
“The amount of devastation is going to be unbelievable,” Rob Witter, a geologist with the USGS’s Alaska Science Center, told The Oregonian in 2009. A 9.0 earthquake could move North America 57 feet west and shift the Earth on its axis by 8 to 20 inches. Much of the Pacific Northwest, from Vancouver, British Columbia to Ashland, Oregon, will be in ruins.
Including, as it turns out, our quaint little city of Corvallis.
Before we go shrieking for the hills, let’s not forget that in 2011 The New York Times named Corvallis as the American city with the lowest risk of natural disaster. Compared to, say, Seattle or Portland, Corvallis may be one of the best cities in the PNW to ride out the next subduction zone temblor. Still, a “Multi-Hazard Mitigation Plan” released by Corvallis Public Works in 2007 admitted that the relative risk of a large earthquake is “high” and the potential damages and losses from such an earthquake are “very high.”
In addition to floods, severe winter storms, landslides, wildland/urban interface fires, and volcanic eruptions, the “mitigation plan” considered two hypothetical earthquakes: an “8.5 Cascadia Subduction Zone Interface Earthquake” and a “7.5 Benioff Zone Earthquake.” In either quake, utility systems would be significantly damaged, including water and wastewater treatment plants and equipment at high voltage substations. Buried pipe systems would suffer extensive damage, approximately one break per mile in soft soil areas. Water will be unobtainable by faucet for at least 10 days. Natural gas will likely suffer the same fate as water. Electricity will be out for 8 to 24 hours; rural areas would experience outages lasting 72 hours. The wastewater treatment plant won’t function for several days. About 3 to 5 percent of the area’s bridges will be destroyed—probably a low estimate.
But the seismic hammer will strike hardest on Corvallis’ historic downtown.
Consider what a 9.0 earthquake will do to the unreinforced brick and masonry of the Madison Building, built in 1907. Or the Whiteside’s brick structure, built in 1922. Or the load-bearing brick wall separating New Morning Bakery from Sedlak’s Boots and Shoes. Or any of downtown’s other two dozen unreinforced masonry buildings with brick veneer, buildings built long before anyone knew of the continental forces grinding away beneath our feet. The same buildings that exemplify the charm and character of Corvallis will be extremely unfortunate places to be in or around when the earthquake commences.
Chris Higgins, an Oregon State University engineering professor who directs the Structural Engineering Research Laboratory at OSU, was blunt about downtown’s chances: “It will be ugly. Really ugly. [A CSZ earthquake] will be strong and go on for a really long time. Most buildings should be able to survive one or two strong pushes, but not sustained shaking.”
An unreinforced masonry building may be able to wobble upright for a minute. Maybe two. The upcoming CSZ earthquake could easily last five minutes. “Think of it as the difference between a 100-yard sprint and a marathon,” Higgins said. “The sprint is bad enough, but if you’re old and weak, you’re not going to last a marathon. Or think of it like evolution: in California, they’ve had enough earthquakes that they’ve essentially shaken out the bad building stock from their genes. But in Oregon, earthquakes happen so infrequently that most of our buildings are old and infirm. ‘The wolf’ is going to come in and thin them out.”
“I’ve often thought about moving.”
There is nothing we can do about plate tectonics. There is little we can do about earthquakes liquefying soils or triggering landslides or rupturing gas and water lines. But there are a number of ways we can lower the risk of downtown Corvallis being reduced to rubble. It’s not just historic buildings that will need such attention, but pretty much any building built before Oregon initiated seismic design codes in 1974. Critical service facilities like hospitals, fire and police stations, emergency shelters, as well as governmental facilities important for post-earthquake response and recovery efforts should be evaluated and receive either structural retrofits or non-structural bracing of critical equipment and contents.
Commendably, Corvallis has made significant progress in upgrading critical city infrastructure. The North Hills Reservoir was seismically upgraded, as was City Hall, the library, the Majestic Theatre, and Fire Station #4. According to Mary Steckel, Public Works director, retrofits on the Madison and Municipal Court buildings are scheduled to begin in 2015. Stabilization projects on Marys River bridge crossings—which carry critical water transmission lines—are scheduled to begin in 2016. Evaluations were completed for Fire Station #2 and #3 and, according to Steckel, “Staff is working on identifying a funding source” to pay for the station’s upgrades so that when the earthquake hits emergency vehicles will actually be able to exit the building.
As usual, funding is the crux of the matter. Seismic improvement projects aren’t cheap. The structural bolstering of City Hall’s unreinforced concrete block and brick exterior cost $1.1 million. Seventy-five percent of the cost was covered by federal grants. In the Age of Austerity, those federal funds will be difficult to secure for future projects. Twelve percent of the total cost for the stabilization project came from property tax supported funds allocated in the City’s Capital Improvement Program (CIP). Now that the HP property tax fiasco has taken an ugly and unfortunate chunk out of the current and future City budget, the CIP’s ability to complete future seismic projects may be severely compromised.
But at least the City of Corvallis seems convinced of the imminent danger posed by a CSZ earthquake and is constrained only by budgets. When it comes to private businesses and individual homeowners, monetary constraints are married to ignorance, apathy, or flat-out denial. After all, the last megaquake occurred a hundred years before the Lewis and Clark expedition. Apocalyptic earthquakes aren’t engrained in our PNW cultural consciousness. As a result, the State estimates that four out of five Oregonians don’t pay for earthquake insurance. Few homeowners have installed even something as simple as a gas line shutoff valve, so that if their house manages to remain upright it won’t be consumed by a ruptured gas line inferno—as most infamously happened when the 1906 San Francisco Earthquake set off fires estimated to have caused 90 percent of the city’s damages.
Additionally, many of the most cringingly collapsible of downtown’s buildings are privately owned. Even if Corvallis building owners are aware that their ancient and brittle buildings are leaning against one another, ready to topple like a house of cards—an awareness which is by no means a given—they might balk at the high costs of seismic retrofits, particularly owners of investment properties. The City of Corvallis can’t force these owners to retrofit their buildings; in the unlikely future scenario that Corvallis mandated such improvements, many owners might choose to abandon their properties. After all, seismic retrofitting isn’t a panacea—generally its objectives are to reduce personal injury and loss of life, not insure the building’s everlasting fundamental integrity. In California’s 1994 Northridge quake, unreinforced masonry buildings that had been retrofitted were still damaged beyond hope of repair and eventually demolished.
Seismic retrofitting can be extremely expensive. But so will the damages caused by a 9.0 earthquake. When the “mitigation plan” accounted for both building damages and “direct damages to contents, infrastructure, and direct economic impacts from loss of function,” the total direct economic impacts of a large earthquake on the City of Corvallis weighed in at $672 million. By comparison, the City’s 2012-2013 budget was under $138 million. All this to say: steps taken to prevent earthquake-related expenses generally ensure a good return on investment, especially in terms of savings on earthquake insurance. Most importantly, safety improvements, no matter how costly, are worth it when it comes to saving lives.
A CSZ earthquake will smite the Pacific Northwest in a way that’ll make the eruption of Mount St. Helens seem like minor tertiary indigestion. It’ll be bad. Really bad. But the effort and willpower and money that we invest into preparation and mitigation will pay off both during and after the quake. It’s the only thing we can do. Because, even now, the tectonic plates are inexorably pressing, pressing, pressing, and waiting to slip.
This article first appeared in the June 20, 2013 issue of <em>The Corvallis Advocate.