Adobe That Survives Earthquakes
by Sophie Arie
When an earthquake measuring 8.1 on the Richter Scale rocked the Andean region for over a minute in June, 2001, the southern Peruvian mountain town of Moquegua was literally shaken to pieces. But amid the rubble, three traditional adobe houses were left intact.
These houses were part of a pilot scheme run by Peruvian engineers hunting for an affordable and effective way to strengthen the traditional mud-brick construction. Such structures house around 11 of Peru's 25 million inhabitants and can collapse in seconds when an earthquake strikes.
"We had tested our method in a lab. But the only way to be sure it worked was to wait for the real thing," said Luis Zegarra, director of research at the engineering department of the Pontifical Catholic University of Peru (PUCP) in Lima.
When the "real thing" came, it killed as many as 135 people, wiped out 80 percent of the houses in Moquegua, and damaged or destroyed 48,000 homes across the region. Over 200,000 people were left homeless, thousands of whom still spend near-freezing nights outdoors, too afraid of aftershocks to risk moving back to their damaged houses. In time, most will rebuild the same fragile houses, knowing they will last only until the next big tremor.
Building from the Earth
Despite strong criticism of adobe as a poor man's death trap, sun-dried mud bricks continue to be the only affordable building material for 35 million people in the Andean region. Mud-and-straw bricks and clay roof tiles are free and available, and people save labor costs by building their own homes. The only outlay — roughly US$4,000 per house in Peru — is for windows, doors, plumbing, and wiring.
In the recent 8.1-force earthquake, 80 percent of the houses in Moquegua, Peru were damaged or destroyed.
A house in the Yacango barrio of Moquegua, reinforced in 1998 (left), fared much better than its neighbors.
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