Environment

OSU Wave Center Demonstrates Effects Of Tsunami On Seaside

OPB | Sept. 13, 2007 6:57 a.m. | Updated: July 17, 2012 1:19 a.m. | Corvallis, OR

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By Colin Fogarty

This week's earthquake in Indonesia was a dramatic reminder of the massive tsunami that hit that region in late 2004.  It killed 230,000 people.

Researchers say America's west coast could be hit by a tsunami that big someday, too.  Thursday in Corvallis, researchers demonstrated what a tsunami would do if it hit the coastal town of Seaside. Colin Fogarty was there.


Tsunami TestThe O.H. Hinsdale Wave Research Laboratory at Oregon State University is a hanger with a giant pool.  It's one of the largest tsunami simulators in the world.

On one end is a concrete beach with buildings that look like wooden monopoly houses and hotels.  It's Seaside.

The unmistakable feature is a rounded pier that overlooks the faux-Pacific Ocean.

A wave machine kicks up a hump of water.  It moves silently and mindlessly.  And then it crashes into town.

The monopoly pieces of town don't actually move or get destroyed in this test.  The purpose here is to see where the water ends up.  Turns out Seaside slopes down away from the beach.

So as in New Orleans — which was flooded after hurricane Katrina — much of the giant wave that goes into Seaside doesn't come out right away.

Dan Cox: "Seaside also is in some places very close to sea level and during a subduction zone event there may be some places that go below sea level."

That's wave lab director Dan Cox.  He says the other surprise about hitting a fake tsunami on Seaside:  That rounded pier on the beach  — clearly not the place to be right when a tsunami strikes — is actually the best place to be immediately after.  That's because Cox says it's higher than other parts of town.

Dan Cox: "It was surprising to me when you think about at the evacuation.  It leads you from on the beach a point of somewhat higher ground down to lower elevations."

Those evacuation routes are of particular concern to researchers at the wave lab.  Here's why.  There are two types of tsunamis — one that's kicked off by an earthquake far away and others from a quake close by.

The wave created by far afield would take three to four hours to hit the west coast.  That gives people some time to escape.  But a quake that starts just off the Oregon coast — and as a subduction zone quake, it would be big — everybody could feel what was happening, according to OSU civil engineering professor Harry Yeh.

Harry Yeh: "You would feel big ground shakings.  So the ground shaking itself is a warning.  And if you have a really big ground shaking, I do not know how reliable the official warning system would work."

Colin Fogarty: "And your point is that if you're on the coast and you feel a strong earthquake like that, you should assume there will be a tsunami."

Harry Yih: "Yeah you should.  Definitely.  Most people should evacuate."

But how to get thousands of people out of town within 30 minutes?  The answer may be what's known as vertical evacuation.  Go up, rather than out of town.  In Japan, some towns have towers like big lighthouses.  So Cox explains how his colleague Harry Yeh did a simulation of what could happen if Seaside had two of these towers when a tsunami hit.

Dan Cox: "The casualties for this simulation is 200.  Professor Yih made another simulation without these towers, but keeping everything else the same, the speed that the tsunami comes, the speed that the people evacuate, the casualty is eight times larger, 1600 people.  I think the take away message for us is we really need to consider for places like Seaside the potential for vertical evacuation."

City leaders in Seaside, by the way, are paying close attention to this research.  And so are leaders in Indonesia.

In fact, the governor of the state of Aceh — the place devastated by the 2004 tsunami — is a graduate of Oregon State.  He plans to visit the wave center in Corvallis soon.

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