10 Technologies That Help Buildings Resist Earthquakes

The Levitating Foundation
Turns out the old Utah State Capitol was thought to be vulnerable to a moderate earthquake, so it snagged its own base isolation system, which was completed in 2007. iStockphoto/Thinkstock

Engineers and seismologists have favored base isolation for years as a means to protect buildings during an earthquake. As its name suggests, this concept relies on separating the substructure of a building from its superstructure. One such system involves floating a building above its foundation on lead-rubber bearings, which contain a solid lead core wrapped in alternating layers of rubber and steel. Steel plates attach the bearings to the building and its foundation and then, when an earthquake hits, allow the foundation to move without moving the structure above it.

Now some Japanese engineers have taken base isolation to a new level. Their system actually levitates a building on a cushion of air. Here's how it works: Sensors on the building detect the telltale seismic activity of an earthquake. The network of sensors communicates with an air compressor, which, within a half second of being alerted, forces air between the building and its foundation. The cushion of air lifts the structure up to 1.18 inches (3 centimeters) off the ground, isolating it from the forces that could tear it apart. When the earthquake subsides, the compressor turns off, and the building settles back down to its foundation. The only thing missing is the theme song from the "Greatest American Hero."