Toll from the Nepal earthquake is past 4,000. Over the last 114 years, 48 quakes have killed 5,000 people or more
Meaning: Earthquake resistant: Key is to allow the building to swing
Quake-resistant buildings, an expression being widely used these days, refer to buildings that are designed to withstand the shock of earthquakes and not crumble. Depending on the seismic zone they are in, buildings are constructed to withstand a certain magnitude of earthquake. But earthquake-resistant is not earthquake-proof. Faced with earthquakes of higher magnitudes, they would go down.
The key idea in making a building earthquake-resistant is to make it ductile, that is, to give it a certain flexibility to shake horizontally. Stiff buildings, when faced with earthquakes, would go down, but the flexible ones would sway and come back to their original position. The idea is to soften the impact of the earthquake, and to let the building absorb the energy.
Most of the newer high-rises these days, especially those in the high-seismic regions, are constructed to withstand the impact of earthquakes of up to a certain strength. Older buildings can also be retrofitted with technologies to make them resistant, even though it involves investments of time and funds. It makes sense to build an earthquake-resistant building — experts say the cost differential in newer buildings is not more than 15 to 20 per cent of the original cost. Retrofitting, on the other hand, might be more expensive.