Long Beach, Washington, has an earthquake and tsunami preparedness problem shared with some other low-lying coastal Northwest places such as Seaside, Oregon, and Ocean Shores, Washington. Many townspeople and visitors likely couldn’t reach high ground in time to escape a tsunami.
So in Long Beach, the city is moving ahead with a plan to bring high ground to them.
If a magnitude 9, full rip of the offshore Cascadia earthquake fault were to unleash a large tsunami, emergency planners estimate the first waves would wash over the long, flat and narrow Long Beach Peninsula about 20-25 minutes after the earth stops shaking.
It’s safe to assume the roads would be buckled or blocked. High ground is more than two miles away from the Long Beach city core, out of reach of all but determined runners.
Civil engineer Rian Johnson of Seattle-based PND Engineers has an alternative.
An Armored Mini-mountain
“A 32-foot vertical evacuation berm that is going to allow students and community members to evacuate and get to higher ground quickly,” he said.
Johnson has drawn up plans on behalf of the city for the elevated tsunami safe haven at an old ball field behind the Long Beach elementary school. The design is essentially an armored, triangular man-made hill, which Johnson calls a “modified prow.”
“The pointed prow of the ship will be looking off toward the ocean,” he explained. “We can actually utilize that shape in order to break the oncoming tsunami and kind of knock down the run up on the structure.”
“Once you get to the top of it, you’ll able to see all the way to the ocean and you’ll be high enough such that there won’t be any structures higher,” he added.
Johnson said the soil to build up the Long Beach structure would likely be granular “structural fill” from a local quarry. The proposed berm has a 0.6-acre footprint.
He said the flat top of this mini-mountain could hold at least 850 people. “You could put more people up there,” Johnson said if for example, the tsunami struck during the peak tourist season. He said the modeled tsunami wave height at the school location — about 0.5 mile inland from the high tide line — is 14.4 feet.
A University of Washington tsunami planning project calculated up to 12 more spaced-out, engineered safe haven berms could be needed to save everyone at risk on the Long Beach Peninsula.
‘They’re Not Going To Run’
Long Beach City Hall hosted an open house last week where townspeople could look over the preferred design. Corrine Kroon can imagine the berm being her salvation.
“It would be great,” she said. “I mean, you’d be alive. Compared to a wave taking you away, you’d be alive. That would be great.”
Locksmith and part-time Long Beach Councilman Steven Linhart imagines it would be terrifying to ride out a tsunami on top of the proposed berm. But he said it’s also a big improvement over the existing alternatives.
“Most people here are retirement-age people,” Linhart said. “They’re not going to run. And a lot of the people here are disabled. Again, they’re not going to run. So whatever we can do to bring that hill closer to our population I think that’s what we need to do.”
Long Beach’s city administrator said some taxpayers have complained the tsunami refuge will be “a waste of money,” but none of them came to the open house.
The small town’s biggest problem for now is raising the money to launch construction. City leaders estimate a total cost of $2.5 million for permitting, design and construction. City Councilwoman Natalie Hanson said they’ve got $1.5 million already, mostly from a Federal Emergency Management Agency grant. But that leaves $1 million more to scrounge up, which is not chump change in a two-stoplight town.
“I would say we’re certainly a couple years away by the time we get funding and start groundbreaking,” Hanson said. “At least a couple of years.”
More Safe Havens
This tsunami refuge berm would be the first of its kind in North America. There are several in existence in Japan.
Earlier this year, Newport, Oregon, officials dedicated Safe Haven Hill, a similar concept. In this case, the forested hill in the low-lying South Beach neighborhood was already there. State and federal grants funded the construction of three trails to the top and the clearing of an assembly area capable of accommodating 2,300 people.
In Westport, Washington, the Ocosta School District built a new gym with a 1,000-person capacity tsunami refuge on top of the roof. The extra strong building was dedicated last June. Meanwhile, down in Cannon Beach, Oregon, city leaders rejected as too expensive a design for a new elevated city hall with an evacuation platform on top.