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Adobe That Survives Earthquakes
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In the past century, over 450 major earthquakes have hit the region of Peru — one of the most active quake zones in the world — repeatedly proving the weak bricks and amateur building techniques to be fatal.
"Usually the four walls are not even joined together," Zegarra explains. "You can see gaps at the corners and between the walls and the roof. That means when there's an earthquake, the walls just flop outward like cards. And the roofs, which can weigh up to 11 tons (10 tonnes), come crashing down, crushing people to death."
During six years of research, funded by the German Cooperation for Development Programme (GTZ), experts at the Regional Seismology Center for South America (CERESIS) and the PUCP have tried all sorts of methods for strengthening existing houses. They tried using bamboo and eucalyptus frames, rope, wooden planks, and steel shafts to hold the basic and often brittle mud structures together.
A Reinforcing Solution
In the end, the simplest and cheapest method has turned out to be "sewing a house together" by nailing strips of electro-welded wire mesh along the inside and the outside "seams" of the walls, and covering them up with concrete.
"The idea is not really to make these houses indestructible," says Dr. Alberto Giesecke, director of CERESIS. "All this is meant to do is win people 10 or 20 extra seconds when there is an earthquake. Enough time to get out of their houses before they collapse."
"The advantage of this method is that it means people can make do with what they have. We are not asking them to pull down any walls. These are just add-ons that can save lives," Giesecke explains.
The technology has already been approved by Peru's Civil Defense authorities who are distributing flyers and manuals encouraging people to use the simple new technology.
Adobe has been used in Peru since Inca times and is fireproof, soundproof, and eco-friendly. For remote Andean mountain communities, it is simply the only option. Transporting other materials from the distant cities would be prohibitively expensive, and many villages are accessible only by narrow mountain tracks.
Families are accustomed to their mud brick homes, which are well suited to the extremes of the Andean climate. They stay cool when it is hot outdoors and retain heat during the cold nights.
Making it Affordable
Although many Peruvians aspire to have homes made with stronger, more "noble" materials like stones or concrete, in reality, millions who live on less than $2 a day will never be able to afford such luxury, costing at least three times the price of an adobe house.
Even the proven reinforcement method is out of many people's reach at around $250 for a typical 650-square-foot (60-square-meter), one- or two-room, single-floor house.
As one group of women left homeless in the dusty hamlet of Polobaya Chica, said in the days after the quake, "We don't want food or blankets donated. What we want is loans so that we can get on and rebuild our lives."
A month after Peru's latest disaster, reconstruction had barely begun. Roads and bridges were still difficult to pass and thousands were in need of emergency food and shelter.
Peru has received loans from the International Development Bank, the World Bank, and the Andean Development Corporation to a total of $215.5 million for temporary rehabilitation and long-term reconstruction of the shattered area.
"As ever," said Giesecke., "the cost of reconstruction is several times more than prevention. But so far, the banks and the international donors prefer to wait until disaster strikes."
However, he added: "We are pleased our models stood up to this quake. We have a vaccine now. We've shown it works. That means the banks will have to take notice."
Sophie Arie is a British journalist freelancing in Santiago de Chile. She has worked for international news agencies in London and Paris and edited a feature service for America Online.
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