ASU Research E-Magazine: Ready to Rock and Roll?

If a major earthquake shakes Arizona, what will happen to hospitals, dams, and power plants? Will we be safe when all the shaking is done?

Probably, thanks to the work of engineers like Avinash Singhal, an ASU professor of civil engineering. Singhal helps design and improve buildings to better withstand earthquakes. He has consulted on critical Arizona structures such as the Palo Verde Nuclear Power Plant, the Stewart Mountain Dam on the Salt River, and several Phoenix-area hospitals.

To earthquake-proof a building, Singhal first looks at its characteristics, such as mass, frequency, and stiffness. Then he assesses the type of earthquake that is most likely to strike the area.

“You try to match the building with the earthquake and find out how much it will damage,” he says.

For example, the Stewart Mountain Dam in Arizona was built in 1930, long before anyone realized that it sat atop a 15-mile fault line. Singhal says the fault could cause an earthquake of magnitude 6.75, somewhat less than the Loma Prieta quake in California, which registered 6.9 on the Richter scale.

Singhal helped fortify the Stewart Mountain Dam against such a possibility. Building materials are an important factor for earthquake resistance.

“Wood is very, very good,” says Singhal. “It’s a very flexible material. But it has limitations. A lot of research is being done on concrete and steel structures. If we can develop a building material with the flexibility and low density of wood, plus the strength of steel, that would be ideal.”

Other cutting-edge work involves designing “smart buildings” that automatically shut down operations or even change their structural characteristics when an earthquake hits.

Smart buildings rely on the fact that earthquakes produce several types of seismic waves. The fastest are body waves called p-waves. Computers can detect p-waves a few tenths of a second before the damaging shear waves hit.

“You don’t have time to evacuate a city, but there are things you can do with that information,” says ASU geologist Simon Peacock.

For example, the Palo Verde Nuclear Power plant is designed to shut down operations automatically in the event of a major quake. Cities can shut off gas mains, limiting the fires that often occur when gas lines rupture. Banks can shut down computer hard drives, protecting financial data.

The Citibank building in New York City provides an example of how a building can change its structure when a quake hits. If the structure detects p-waves, oil is pumped into hollow chambers, changing the mass of the building and making it more resistant to the shaking.

How to “Earthquake-proof” a Building

Engineers have devised several ways to earthquake-proof a building, including:

Use a bracing to “tie down” the building.
Change the sizes of the beams or columns.
Partially bury the building, using soil as resistance.
Suspend the building from the top down, so that it doesn’t actually rest on the ground.
Place a layer of material between the building and ground that allows the surfaces to slide against each other.

—Diane Boudreau