The recent earthquakes in Mexico came at an unfortunate time, considering that so much U.S. aid personnel are tied up in Texas, Florida and now Puerto Rico following three hurricanes.
The state of Puebla, just south of Mexico State (formerly called Distrito Federal) is densely inhabited. In a series of 10 quakes last month, the most terrifying one occurred on Sept. 19 near the city of Puebla, affecting 3 million residents.
By comparison, greater Atlanta counts about 2.5 million. Puebla is home to major industry, including the massive Volkswagen factory. The magnitude 7.1 quake comes close to the 7.5 that in 1985 caused 10,000 deaths in Mexico City.
Low buildings seem to be less affected than ones measuring six to nine stories. This became apparent after the 2001 quake in Bhuj, India. The Indian Express newspaper reports that the “city that learned its lesson” now permits only earthquake-resistant buildings, and no taller than one story. Thousands of new developments there now meet earthquake codes. The new hospital is certified to withstand magnitude 8.5.
Mexico straddles a plate boundary, or fault line, extending from Chile all the way to Alaska. Population has grown strongly in the 21st century. The Mexico City basin has an estimated 20 million inhabitants, living near the edge where the Pacific Plate and the Cocos Plate are colliding. In addition, two active volcanoes are towering over the megacity.
On the U.S. side of the fault system, California isn’t clear of trouble. On Highway 198, between Coalinga and San Lucas, is a spot where one can overlook the San Andreas Fault. Shallow ponds indicate depressions caused by ground movement. Trees are tilting on the slopes. Farther north, in the San Francisco Bay area, the fault is locked. Periodically a plate will break loose, causing a jolt that’s harmless to the planet. To us, it’s a devastating earthquake.
Unlike the recent hurricane disasters, quakes aren’t a sign of a change in the Earth’s systems. They have occurred for millions of years, adjusting the building blocks of the globe as they drift on molten rock underneath. The real change in all this is the rapid growth of population on top of unstable plate margins. More deaths and suffering will result from such unfortunate placement of millions of people. Adopting the strict “Bhuj model” might be a step toward lessening the earthquake threat.
Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His column appears Sundays and at gainesvilletimes.com.