What We Still Don't Know About Earthquakes

We were having lunch in a local greasy spoon when the first wave of dizziness swept over me. I figured my wife, a nurse, would be alarmed if I told her, so for a moment I kept my mouth shut.

"I feel dizzy," I finally said.

"So do I," she responded.

A potted plant, swinging gently back and forth over our table, offered the strongest clue of what was going on.

"It's an earthquake," I said, profoundly.

The rickety restaurant near our home in Juneau, Alaska, swayed as the ground rolled like waves on a troubled sea, the clear symptom of a distant earthquake. And it seemed to last forever, revealing that this was no minor temblor.

During my years of chasing quakes and their aftershocks in Southern California for the Los Angeles Times, I had felt many temblors, but this one was a dandy.

The quake measured 7.9 and was centered about 400 miles away. It was one of the largest ever recorded on U.S. soil, according to the U.S. Geological Survey, and ripped across central Alaska on Nov. 3 with a jolt that was strong enough to be felt thousands of miles away.

Progress and Pitfalls

It also revealed just how much progress we have made in earthquake engineering. And how much we still don't know about the science of earthquakes.

We know how to design structures to withstand enormous forces. But we still don't know how to figure out when those forces will strike, what triggers the release of all that energy, and in many cases how the ground beneath our feet will perform.

Those are pretty basic questions, and the complete answers are still beyond our reach.

The quake left a 145 mile scar across the landscape and in some areas the land on the opposite sides of the Denali fault moved horizontally by 22 feet — proving wrong scientists who had thought that changes in seismic stresses had left the old fault unable to produce such a major quake.

Alaskan Pipeline Marvel

The nearby trans-Alaska pipeline that carries oil from the Arctic to the Port of Valdez came through the rumble with some damage, but no rupture — proving that the engineers who designed the $8 billion pipeline were right when they claimed it would withstand even a larger quake than the Nov. 3 temblor.

A lot of folks hadn't believed them.

The pipeline is indeed an engineering marvel. The 800-mile-long steel tube crosses three mountain ranges, 800 rivers and streams, and three active faults as it winds its way across a young and dynamic landscape that is still very much a work in progress.

The engineers who designed it knew the pipeline would have to be flexible enough to withstand a large quake, although some now say they didn't think it would have to experience anything as powerful as the 7.9 shaker, which is supposed to happen in that area about once in 600 years.

It is supported by shoes that can slide back and forth on horizontal beams. The design allows for movement of 20 feet horizontally, and 5 feet vertically. During the quake, sections moved nearly 8 feet horizontally, and nearly 3 feet vertically, so it could have handled even more.

Cocksure Engineering

So where does that leave us? Probably a bit too cocky.

We know, for example, that well-engineered structures have saved thousands of lives during recent earthquakes. But we don't know just how safe some of our structures really are.

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