NatDis - Seattle Times: Why such a big quake didn't do more damage

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Thursday, March 01, 2001, 12:00 a.m. Pacific

Why such a big quake didn't do more damage by Alex Fryer and Duff Wilson Seattle Times staff reporters

We were prepared, and we were lucky.

That's the assessment from seismologists, structural engineers and emergency officials after the Nisqually earthquake rattled nerves and windows from Bellingham to Portland yesterday morning.

The 6.8-magnitude quake caused few serious injuries and relatively limited property damage. By comparison, a 6.7-magnitude quake hit Los Angeles in 1994, killing 72 people and causing an estimated $15.3 billion in damage.

Seattle escaped widespread devastation because the epicenter of the quake was 30 miles deep and because engineers have been preparing for the Big One for decades. Newer office towers and residential buildings are designed to withstand tremors far more violent than yesterday's shudder.

Damage in the Seattle area was limited mostly to turn-of-the-century buildings in Pioneer Square. And property owners who had seismically retrofitted their historic buildings fared much better than those who hadn't.

Yesterday's quake began deep under the earth, much like the quakes that shook Seattle in 1949 and 1965. Because the Los Angeles quake was shallow, the damage it did was much greater.

The depth of yesterday's quake mitigated the impact above ground, said Steve Kramer, a structural engineer at the University of Washington who studies seismic activity.

"If it was shallow, that would have caused widespread damage," he said.

Earthquake preparedness has been part of the public consciousness here for decades, and yesterday it paid off.

Seattle City Councilwoman Jan Drago said the city's efforts to prepare public buildings against quakes saved millions of dollars and countless lives.

"If this had happened 10 years ago, it would be a very different story," she said.

Still, long-term costs are unknown. The King County Courthouse was evacuated, and officials don't know when the 85-year-old building will reopen. The Alaskan Way Viaduct will be closed through this morning's commute.

Schools across the city were temporarily evacuated.

Downtown high-rises were also spared major damage.

Pioneer Square was hit hard for two reasons, said John Hooper, principal of earthquake engineering at the firm Skilling Ward Magnusson Barkshire.

The neighborhood is built on infill, loose soil that is different from other areas of the city such as the University District, which rest on solid glacial till.

It's also one of the oldest neighborhoods in the city. Many of the buildings are built with bricks that shatter in a quake.

The city of Seattle does not mandate seismic retrofitting of historic buildings, unlike both Los Angeles and San Francisco. "Maybe this will spawn the concept," Hooper said.

Samis Land owns 14 buildings in Pioneer Square. The buildings that were retrofitted survived perfectly, said William Justen, land director for Samis. Those that weren't suffered mostly minor damage, such as cracked walls and ceilings.

The biggest earthquake retrofit on the West Coast saved the biggest occupied building in the state.

The Starbucks Center, formerly a Sears catalog distribution center, was built on tidal fill near Elliott Bay 89 years ago. The landmark brick building is nine stories high and 1.8 million square feet in size, bigger than the Columbia Center.

"It's really rewarding to know with the pains we took and the money we spent on behalf of the building, that it worked," said Angi Davis, property manager of Starbucks. "Everybody came out alive."

When Starbucks expanded its offices three years ago, the city of Seattle asked for an earthquake upgrade.

The owners spent $8.5 million on steel "X" frames, like a pyramid, and other earthquake work inside the building, Davis said.

"If those braces weren't there, we'd be looking at a pile of rubble," one worker in the parking lot said yesterday.

Nearly 2,000 people were inside when the quake hit. They crawled under desks and tables and stood in doorways.

"It felt like a typhoon coming through," Starbucks Vice President Rick Arthur said. "The floors rose in big waves. At first we felt it was a fairly minor event, but it kept going and building in intensity. The lights were swinging in big arcs."

Arthur said his first thought was, "Thank you, Terry."

Terry Lundeen managed the earthquake retrofit job for the structural engineers Coughlin Porter Lundeen of Seattle.

After a walk-through in a hard hat yesterday, Lundeen said the building acted as it should.

"For the big picture, I'm pleased," Lundeen said. "Really, the earthquake that we're trying to protect lives with is bigger than this one."

The building didn't escape unscathed. Some of the walls cracked and bricks fell from the exterior. A four-foot brick parapet on top of the building broke loose and crashed to the sidewalk, but Davis said that wasn't unexpected. Nobody was hurt. The most damage was caused by broken water pipes.

Seattle Chocolate wasn't so lucky.

Located at 1962 First Ave. S., Seattle Chocolate may be torn down after the quake tilted two walls, breaking them away from the roof. Built at the turn of the century as a horse stable, the building had not been retrofitted for earthquakes.

-- Anonymous, March 01, 2001

Answers

Much of Northwest ready for earthquake

By Bernard Mcghee, Associated Press, 2/28/2001 20:52

SEATTLE (AP) It was the largest earthquake in the Northwest in more than a half century, but most of the region's buildings and bridges made it through relatively unscathed.

The earthquake started deep in the earth, some 30 miles down, which meant much of its energy was diluted once it hit the surface, said Bill Steele, a seismology lab coordinator at the University of Washington.

Its impact wasn't concentrated in any one place.

''Clearly, this was the best possible kind of magnitude quake one can have,'' Steele said.

Experts also credited efforts to make structures in the area more capable of withstanding earthquakes. Most buildings built since the mid-1970s comply with seismology codes designed to make them capable of standing up to quakes much stronger than the one Wednesday.

''The code worked, but it wasn't tested to the full extent,'' Steele said. ''We're kind of below the threshold of the current code design factors.''

Vikram Prakash, an associate professor at the university's architecture department, studied structures in India last year before a devastating earthquake in January. Prakash said contractors skimped on materials, worsening damage from the 7.9-magnitude earthquake that killed nearly 20,000.

Building codes here made structures much better able to withstand Wednesday's quake, Prakash said. For example, most residential buildings are made with wood, which is better suited to adjust to earthquakes than masonry. And taller buildings have vertical walls running through them, making them more rigid, he said.

Without such preparations, ''I'm sure we would have seen a lot more (damage),'' he said.

There were no reports of major damage to bridges, the state Department of Transportation said.

A $65 million retrofitting program that began in 1990 improved more than 300 bridges across the state, said Ed Henley, a bridge management engineer for the department.

By early Wednesday afternoon, Henley said he knew of no bridges that were extensively damaged in the quake, although several remained closed for inspection.

''We don't have any red lights going off,'' Henley said. ''We would look at the retrofit program as having paid for itself and shown a success.''

-- Anonymous, March 01, 2001


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