BE VERY AFRAID (Seattleites) | The Stranger

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BE VERY AFRAID
by Erica C. Barnett



The Alaskan Way Viaduct is a Disaster Waiting to Happen. It's Time to Stop Talking and Start Working.

At 5:46 a.m. on January 17, 1995, the earth began to move.

The shaking, which clocked in at 7.2 on the Richter scale, began some 12 miles beneath the surface and continued for just 30 seconds. But the toll, both human and infrastructural, was immense: More than 6,500 lives, 50,000 buildings, and a major elevated expressway--the backbone connecting two large urban centers--were lost.

The earthquake took place in Kobe, Japan. The elevated highway was the Hanshin Expressway, a 40-kilometer-long viaduct that ran along the narrow corridor connecting two cities, Kobe and Osaka, on Japan's main island. But it could just as easily have been Seattle's Alaskan Way Viaduct, which, like the Hanshin, sits on a powder keg of unstable soils and colliding tectonic plates. Among other similarities, both Kobe and Seattle ride on the boundary between two plates and are pocked with dozens of shallow, earthquake-prone faults. According to University of Washington civil engineer Charles Roeder, such areas of colliding tectonic plates, known as subduction zones, "produce the largest earthquakes that have ever been recorded."

If the viaduct goes, it will happen something like this: As the ground begins to shake, the loose, watery soil underneath the viaduct will fail, putting pressure on the 70-year-old seawall that provides some of the structure's support. If the seawall collapses, it could take the viaduct's foundations down with it. University of Washington earthquake expert Steve Kramer says that in the "doomsday scenario"--a large, shallow earthquake along the Seattle Fault, which the viaduct traverses--"the viaduct collapses." It wouldn't even take a catastrophic quake. According to a study of the viaduct Kramer coauthored all the way back in 1995, "significant damage is likely even if the motion is considerably less intense, and hence more likely" to occur than a doomsday-level earthquake.

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