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Chile's Earthquake: We Can Protect Ourselves
Buildings Can Be Buttressed, or Designed to Sway Instead of Collapsing

We've now seen the destruction after the earthquake in Chile, and the utter devastation after the earthquake in Haiti.

Could such earthquakes happen here? They have before and will again. Can we protect against them? Yes.

Some years ago I found myself on a catwalk beneath the San Francisco-Oakland Bay Bridge, wearing jeans, work boots and a body harness.

The 1989 Loma Prieta earthquake had happened years before. Now California was trying to get ahead of the game.

Cuts would be made in the beams supporting the bridge, just beneath the roadway. Sections of steel would be pulled out, and replaced with "isolation bearings" -- flexible joints that sometimes look like gargantuan shock absorbers.

It was an ambitious, expensive plan, which quickly got caught in bureaucracy. Before much of the work was done, California decided it needed to replace much of the aging bridge anyhow.

Swaying Instead of Giving Way

But San Francisco's city hall is now on 590 isolators, installed in the hope that if the ground vibrates, the building will more gently sway back and forth above it. The building won't escape damage if The Big One hits, but engineers say it is far less likely to collapse.

These are examples of how structures in earthquake-prone areas can be designed to survive a disaster -- the kind that happened Saturday in Chile.

"This is the ultimate earthquake," said Peter Yanev, a California-based structural engineer. "This is the earthquake that we can learn the most from, both the positive and the negative."

"Buildings -- designed to withstand gravity -- have to be built to withstand lateral motion," said Art Lerner-Lam of Columbia University's Lamont-Doherty Earth Observatory.

Which is where those isolators come in. They're expensive -- unless a major earthquake hits.

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