Mexico City’s new building code tested by earthquake

Nature : Mexico City, which was devastated in 1985 by a magnitude-8 earthquake that killed 9500 people, has since become a model for earthquake protection in the developing world. In the wake of the quake, the country changed its building regulations and pushed for better design and materials. The design had to take into account the city’s unique location—it was built over a lake that was gradually filled in by the Aztecs and, later, the Spanish. In an earthquake, the loose landfill tends to vibrate at just the right speed to enhance the shaking, and thus amplifies the quake long after the quake itself has dissipated. Last Tuesday, the renovations were put to the test when a 7.4-magnitude earthquake struck. This time around, there was little damage and no deaths. Although the quake was only a third as strong as the one in 1985, it should generate massive amounts of valuable data. “Mexico City in 1985 was a wake-up call for the engineering profession,” says Sergio Alcocer, a professor of engineering and secretary general of the National Autonomous University of Mexico in Mexico City. “Engineering has improved.”