DisastersLessons from Japan's tsunami could dramatically shift building codes

American tsunami experts and engineers are scouring the devastation wrought by the 11 March earthquake and tsunami to analyze how structures fared during the natural disasters and what lessons can be applied to U.S. building codes.

Harry Yeh, a tsunami expert at Oregon State University, was utterly stunned by the damage caused by the towering sixty foot wave that swept across Japan’s northeastern coast.

Yeh has visited nearly every tsunami zone including Nicaragua in 1992 and the Indian Ocean in 2004, but was still surprised by how much damage the most recent tsunami caused.

“The Sendai plain, it’s so vast it’s just incredible,” he said. “I’d never seen this type of site before. I was totally, totally stunned.”

His shock was in large part caused by the sight of a four-story reinforced concrete building that was knocked over by the tsunami in Onagawa, a fishing port just east of Sendai.

According to Yeh this building could likely change existing norms surrounding tsunami preparedness, evacuation procedures, and building codes.

He explains, “Up to now, we thought reinforced-concrete buildings were safe. So we recommended to people that if they don’t have time to escape a tsunami, find a reinforced-concrete building and climb up to the fourth floor.”

He was careful to note that many reinforced-concrete buildings were able to withstand the tsunami, so the destruction of one building may not invalidate existing norms regarding building construction or survival tactics.

Many residents were saved by “vertical evacuations” by heading to the tops of buildings in the tsunami zone, but many were not so fortunate.

Despite strict building codes and quick evacuations to higher ground, the sheer power of the tsunami overpowered defenses and the death toll is estimated to be more than 28,000 people.

Steven Kramer, an earthquake expert at the University of Washington, who was visiting with Yeh, said, “After seeing tsunami debris hanging on the sides of hills some 60 feet over my head — and cars on top of four-story buildings — in Onagawa, I doubt that the general public is fully aware of just how bad things can get.”

Hiroshiko Oka, a local bar owner who survived the earthquake and tsunami, said, “There were people who went up to the tops of three- and four-story buildings” that were killed when the waves crested the buildings.

Japan has led the world in earthquake and tsunami preparedness maintaining strict building codes and practicing evacuation drills, which allowed it to emerge largely unscathed from the 9.0 magnitude earthquake.

“If it wasn’t for the tsunami,” Kramer said, “I think the Japanese would be considering the damage of this earthquake to be a great success story.”

While Japan has made elaborate preparations for tsunamis and earthquakes, Kramer and Yeh worry for America’s West Coast which is significantly less prepared than Japan.

Kramer said, “The Northwest is much less prepared than California, and California is much less prepared than Japan.”

“Part of that is human nature — the Japanese are reminded that they live in earthquake country all the time, and we aren’t. Their governments and private firms have also been willing to invest in earthquake-resistant infrastructure and earthquake preparedness. Ours haven’t,” he explained.

According to Yeh, Oregon’s coastline has very few concrete reinforced structures like the ones that saved hundreds of lives in Japan.

Yeh strongly advocates that coastline communities in the United States consider implementing codes that would mandate that reinforced concrete be used for new buildings, especially public structures.

He points to Oregon’s Seaside parking garage – a five story parking structure with interior shear walls that have been seismically reinforced – as a good example.

Oregon shares many similarities with Japan’s northeastern coast including its isolated coastal communities separated by mountain ranges. More dangerously, Oregon also has an undersea subduction zone, where an oceanic plate is pushing beneath a continental plate, although Japan’s offshore trench is much deeper.

Yeh warns, “We do not know what kind of rupture process we’re going to have” for that undersea plate.

Kramer and Yeh have already visited the areas hardest hit by the tsunami in advance of other teams of U.S. experts, who they will guide on fact finding missions.

The experts hope to take back valuable lessons that will minimize the destruction from a similar event in the United States.