To Withstand Tsunami, Coastal Oregon Town Plans to Put City Hall on Stilts

Cannon Beach, Ore., aims to get the nation’s first tsunami evacuation building off the ground by 2014.
by | March 25, 2011

Facing forecasts that a major earthquake and tsunami will pummel the Pacific Northwest, a city hall in a coastal town in Oregon is literally rising to the challenge in a way this country has never seen.

On the northwestern edge of Clatsop County, Cannon Beach, Ore., sits in the red zone of extreme seismic tension, similar to subduction zone that provoked the catastrophe in Japan. Rather than wait around for the inevitable, city officials want to stand up to Mother Nature by putting their City Hall on stilts, which would protect the building from tsunami damage and provide an emergency evacuation space for residents and tourists who can’t get to higher ground in time. With a price tag of about $4 million, the new City Hall would be the first tsunami evacuation building in the U.S.

“We could basically make sure our City Hall would survive and provide another option for people who couldn't get to high ground and save lives following an earthquake and tsunami,” said Jay Raskin, former Cannon Beach mayor and an architect who is helping spearhead the design process.

About 75 miles off the Pacific Northwest coast, two of the Earth’s tectonic plates collide, divided by a 600-mile-long fault running from northern California to Vancouver called the Cascadia Subduction Zone. As the plates converge inch by inch, stress accumulates. The abrupt release of that stress can trigger earthquakes. It has been more than 300 years since the last Cascadia earthquake. All that stress has been building up. Scientists say there’s a one-in-three chance that a massive 9.0-magnitude earthquake will launch a giant tsunami into the West Coast in the next 50 years.

When the ground starts shaking, Raskin said, people on the coast have about 20 minutes to get to higher ground before the brutal wave strikes. About 1,700 people live in Cannon Beach, with 50 percent of residents and 75 percent of businesses in the tsunami zone. On busy weekends, tourists flocking to the beach can boost numbers to 5,000. City officials still say the best solution is to get to higher ground as soon as possible, and the new City Hall would have room for about 1,500 people, who have mobility issues or don’t know where to go.

“We realized that evacuation wasn’t one-size-fits-all,” Raskin said. “We think, by and large, the people coming to City Hall will be the stragglers, who have no other option.”

Learning from Hurricane Katrina, city officials realized how crucial it is to keep government afloat in the midst of disaster to protect people and enhance relief efforts. Relocating City Hall out of the danger zone wasn’t an option, so officials began brainstorming ideas for a upgraded structure, based partly on a 2008 FEMA publication, Guidelines for Design of Structures for Vertical Evacuation from Tsunamis. By September 2009, the Cascadia Region Earthquake Workgroup (CREW) held the Pacific Northwest region’s first workshop on tsunami vertical evacuation buildings (TEBs).

Credit: Ecola Architects, PC

The Cannon Beach City Hall design, developed by the city and Oregon State University, features concrete stilts almost 15 feet long, reinforced with steel cables. The beams would be supported by concrete piles at the base of the 9,800-square-foot building, which would help prevent the powerful waves from wearing down the foundation. A study by the Oregon Department of Geology and Mineral Industries (DOGAMI) indicated that this structure would be safe from 90 percent of all possible tsunamis.

As researchers continue with simulations of tsunamis against a City Hall model, officials are in the process of creating a package of local, state, federal and private funding. Such buildings exist in other countries such as Japan and Indonesia, Raskin said, but as the first of its kind in the U.S., the new City Hall could become a model for more tsunami evacuation buildings in other coastal communities at risk.

Despite the devastation in Japan, experts say the nation was more prepared for disaster than the U.S. And other recent tragedies highlight the importance of planning ahead. A  2010 DOGAMI report cites countries like Haiti, for instance, which had virtually no building codes. The 7.0-magnitude earthquake leveled hundreds of thousands of buildings and killed some 200,000 people. On the flip side, the 8.8-magnitude earthquake in Chile resulted in about 500 deaths with many buildings still standing. The difference?

“Awareness of the magnitude of the risk,” wrote Vicki S. McConnell, Oregon State Geologist in the report, “and willingness to address social issues like enforcing strict building codes and outreach and education of the general public.”

The massive earthquake and subsequent tsunami in Japan this month has boosted efforts in the Cannon Beach project. “Advances in structural engineering for earthquake and tsunami active areas mean our buildings can be designed to be safer,” McConnell wrote, “and to be more likely to withstand a geologic process.”

Raskin wants to have the project finished by March 27, 2014, the 50th anniversary of the 9.2-magnitude Alaskan earthquake in 1964 that triggered a tsunami which washed away a bridge on the north side of Cannon Beach and killed people elsewhere.

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