OREGON STATE UNIVERSITY

Seaside Model to Study “Vertical” Tsunami Escape

09/12/2007

CORVALLIS, Ore. – Seaside, Ore., which has good warning systems, evacuation plans and a reputation as one of the more “tsunami-prepared” communities in the world, will soon get a chance to see whether those plans work and just what these really big waves are like – over, and over, and over, and over again.

As its buildings and infrastructure are repeatedly overwhelmed by giant waves that come rolling in after a massive earthquake, the good news is that it’s all being done in a research facility at Oregon State University – and the findings should help not only that community, but many more like it, determine how best to plan for and live through a catastrophic tsunami.

Sitting just miles from the Cascadia Subduction Zone, a geologic fault structure very similar to the one that caused the massive tsunami in East Asia in 2004 and killed about 230,000 people, Seaside will provide a model system to study tsunami behavior, building safety and other issues.

In particular, engineers and scientists want to find out whether many people might be better served by going above, rather than away from an imminent tsunami.

“The Japanese, who have been living with tsunamis for centuries, have developed systems of both conventional evacuation and shelters that are above the wave, and can withstand its force,” said Dan Cox, a professor of coastal and ocean engineering, and director of the Hinsdale Wave Research Laboratory at OSU. “The U.S. has not really considered that option.”

“But realistically, there will not be much time for whole coastal populations to evacuate to higher ground following a subduction zone earthquake that is very nearby,” Cox said. “We need to find out more about what the impact on structures will be from a tsunami, and whether vertical evacuation to certain buildings is a viable approach.”

Perfectly suited for that project is the $5 million Tsunami Research Basin at OSU, created with funding from the National Science Foundation through its Network for Earthquake Engineering Simulation, or NEES Program. This unique facility, operated by the OSU College of Engineering, has been turned into a working model of Seaside, with similar undersea terrain, shoreline, and miniature buildings, all waiting for the big one to hit.

And hit it will. Construction on the new model is now complete, sensors are being installed, and this winter the tsunamis will be coming in with regularity. Researchers say the studies on this simulation may take years, but will provide an enormous amount of data and information about how structures withstand the impacts, how the undersea terrain affects the tsunami, how debris can turn into “battering rams” that compound the problems, and many other issues.

Perhaps more than any other coastline in North America, the area from southern British Columbia to Northern California is at great tsunami risk, because of the Cascadia Subduction Zone. An area once believed to be fairly seismically stable – at least by Southern California standards – is now known to be vulnerable to the greatest earthquakes of them all, the types caused by subduction zones.

These massive earthquakes and related tsunamis, such as the one that hit Alaska in 1964 and more recently destroyed villages, towns and cities all over the Indian Ocean, are the most powerful seismic events in the world. They can last for minutes, cause massive building destruction, enormous tsunamis, and in the case of the Pacific Northwest, will come with comparatively little warning.

Scientists say there is a 14 percent chance that the Cascadia Subduction Zone event will happen in the next 50 years. It is believed to be about 300 years since the last known break on this subduction zone, and stresses have been accumulating since that time.

What would that mean to Seaside, or other communities like it? To start, the first massive waves might arrive within 30 minutes. It could happen at any time, during the day or the middle of the night. Many people, especially unaware tourists or the elderly, may not be able to evacuate vulnerable areas in time.

In this research, scientists will study water flow speed, flow depth, potential forces on infrastructure, and how realistic it is to believe that existing or new structures could serve as close, elevated places people could go to, in order to get above the waves. Computer simulations of such events will now be compared to the “ground truthing” provided by real, physical models of wave impacts.

The study, which is being funded by the Oregon Sea Grant program, will also include interaction with coastal officials and residents, keeping them aware of the findings and the procedures that would be most effective in the event of a tsunami. International interest is expected in the project. And the wave research facilities will allow different scenarios to be explored and tested – over and over again - until scientists fully understand the forces at work.