- John Coletta
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Chile, Haiti Earthquakes Point to Need for Quake-Proof Buildings
Two massive earthquakes in a single month – an 8.8 trembler in Chile and a 7.0 quake in Haiti – have raised the question of whether engineers can design buildings that don’t crumble when the earth’s tectonic plates crash against one another. Although the simple answer is that the technology exists to make buildings almost earthquake-proof, the cost of rebuilding sprawling cities that are hundreds of years old would be prohibitively expensive.
“Most disasters are created by human beings. It’s how we build and where we build that creates the hazard, the disaster,” said Michael Armstrong, senior vice president of the International Code Council, a non-profit organization that develops building codes. “Earthquakes, hurricanes, fires, floods are going to occur, but there are ways in terms of where we build and how we build that can reduce the impact.”
Essentially, the technology that prevents buildings from collapsing during earthquakes works by making buildings stronger or more flexible so they sway and slide rather than crumble. For nearly three decades, engineers have constructed skyscrapers that float on systems of ball bearings, springs and padded cylinders. Because these buildings don’t sit directly on the earth, they are protected from some earthquakes. During a major earthquake they may sway a few feet in synch with the tremor.
Mehmet Celebi, a senior research civil engineer with the U.S. Geological Survey, pointed to a striking example where buildings constructed with base isolation performed exceptionally in earthquakes while others did not. Base isolation is a collection of structural elements which should substantially decouple a superstructure from its substructure resting on a shaking ground, thus protecting a building’s structural integrity. He cited a University of Southern California hospital in Los Angeles that came through the 1994 Northridge earthquake with no damage. A nearby hospital that did not incorporate the same technology suffered significant damage.