Seaside the ‘highest risk community’ on coast for tsunami

Published 4:00 pm Monday, November 4, 2013

The experts have spoken; there is no controversy on the matter.

The big one — an earthquake reaching as high as magnitude 9.0 and possibly higher — has a 10 to 15 percent chance of striking somewhere just off the U.S. west coast in the Cascadia Subduction Zone within the next 50 years. Fifteen to 20 minutes later, a tsunami will move in and drown many coastal communities.

When it happens, Oregon is likely to experience some of the worst of the fallout. And the city of Seaside is the highest-risk community on the Oregon coast, said Yumei Wang, a geotechnical engineer at the Oregon Department of Geology and Mineral Industries.

Its the largest natural hazard facing the state of Oregon, said George Priest, the tsunami specialist for DOGAMI. That earthquakes going to affect the whole western half of Oregon, seriously. And the tsunami is the major way you could lose thousands of lives.

Hence, SAFE

Its no wonder, then, that earthquake and tsunami preparedness is one of the Seaside School Districts main selling points for bond measure 4-168, which would fund a new $128.8 million K-12 campus to be built in the wooded hills east of Seaside Heights Elementary School.

In the event of a natural catastrophe, the building housing the schools would double as an emergency shelter for the community.

These two concerns — a new learning environment for schools above the 80-foot tsunami inundation zone and the need for a refuge from a Japanese-style disaster — are the basis for SAFE (Support a Future for Education), a political action committee formed to generate support for the bond.

Our kids need to be prepared for the 21st century in education. Our (Seaside School District) schools arent doing that now, SAFE Co-Chair Mary Blake said. There are lives at stake here, the future of our kids being educated as well as the future of our community.

The committees Run For Your Life rally, held earlier this month, was designed to raise awareness of the district schools hazardous low-lying locations. Participants trekked from the Seaside Kids ball field on Wahanna Road at 15 feet elevation up to 130 feet, where the proposed campus will lay its foundation.

The K-12 campus will replace Seaside Heights and Gearhart elementary schools, Broadway Middle and Seaside High schools.

Though these schools average close to 60 years old, state law will not allow the district to significantly remodel them because the schools lie in a tsunami inundation zone, noted Seaside School District Superintendent Doug Dougherty.

An earthquake alone would likely destroy much of the districts facilities, seismically unsound as the buildings are. Whatever remains — including the students and teachers trapped inside them — will likely be taken by the tsunami.

Thats why we have to be above that (80-foot) elevation to build our schools, Dougherty said.

The planning carried out by Seasides Tsunami Advisory Group for the past several years has really coalesced around the idea of having this school up there, said SAFE Co-Chair Doug Barker, an active member of TAG.

Were trying to educate people to survive, but once they survive, now youve got to house them and feed them for the next however many months, Barker said. Thats where the school comes in.

The city has evacuation areas on Tillamook Head Trail, Copper Street, Sunset Hill and Skyline Drive, but those are intermediate. Those are temporary, Barker said.

You need something permanent, long-term, because youre going to be here for a long time, he said, adding that many people have trouble conceptualizing the aftermath of an earthquake and tsunami. Everythings going to be gone. Theyre going to go from a first-world to a third-world country in whatever length of time the earthquake is.

Thats why were doing this, Dougherty said.

Scary science

Opinions regarding the new campus and the ballot measure funding it aside, the science underwriting SAFEs concerns is sound.

There have been 42 Cascadia subduction zone events that geologists can distinctly identify. Of those, 20 were full ruptures of the entire zone. That averages out to a major earthquake every 238 years or so.

Its a very frequent event geologically, said George Priest, tsunami specialist for DOGAMI.

The last time the Pacific Northwest endured a mega-quake, according to geologic evidence and records from Japan, was in the year 1700. That one was a monster, Barker said.

The scientific consensus is that we are long overdue for the next one. Many west coast communities are living on borrowed time.

Earthquakes do damage, but tsunamis kill people. Tsunamis are very effective at killing people within the inundation zone, Priest said. The combination of them coming at the same time is whats so incredibly devastating.

When the water rushes in and scours the city, not only will it come at high speed, it will carry tons of debris along with it.

Seaside must look forward to experiencing extreme damage, Wang said. If you are hit by a tsunami, even if its in a foot of water, you are in a lot of trouble.

Because of its low elevation, the city is in a particularly vulnerable spot.

(The tsunami) will bring forceful water in and flood the low-lying areas, she said. Its impossible to tell how far inland it will come, but we have done models that suggest it will come inland quite far.

Peter Ovington, DOGAMIs geologic hazards outreach specialist, agreed.

The inundation is expected to go quite far east, Ovington said.

He added that the Necanicum River and Neawanna Creek, two north-south waterways, present a barrier for people in downtown Seaside trying to evacuate eastward; the bridges, such as those on Broadway and Avenue G, may collapse during the earthquake.

Theres going to be the vertical drop that happens with all subduction zone earthquakes, but what you also have is a lateral shift (of the land), Dougherty said.

This is liable to split roads in some areas, pulverizing them in others.

We all know the lessons from 2011, (when the earthquake and tsunami hit Japan) said Harry Yeh, professor of civil and construction engineering at Oregon State University. The tsunami is not predictable; they tend to go beyond the prediction.

Taking these realities into account, Jay Raskin, a former Cannon Beach mayor and current vice chair of the Oregon Seismic Safety Police Advisory Committee, fully endorses the bond measure.

I think this is one of the most positive, forward-looking things that the district could have done, Raskin said. It will save the lives of students and teachers and will provide a very serious backup relief effort.