for National Geographic News
Unless protective measures are taken, once every century or so when the Earth trembles in a violent release of pent up tension, buildings will tumble, streets will buckle, and pipelines will snap, leaving upwards of a million people crushed beneath the debris.
That is the conclusion of Roger Bilham, a geological scientist at the University of Colorado at Boulder who studied the potential impact of earthquakes on the world's rapidly expanding urban populations in the 21st century.
To avoid such catastrophes, earthquake-resistant construction practices must be adopted and enforced around the world, said Bilham, who is a fellow in the university's Cooperative Institute for Research in Environmental Sciences.
"Most countries have earthquake resistant codes," he said. "The problem is often a matter of enforcing them."
Many of the world's largest so-called "supercities" with populations of 2 million to 15 million are located near fault zones that have caused major earthquakes in the past. Population in many of these cities is expected to continue expanding.
Earthquake experts from around the world tend to agree with Bilham's suggestion that the consequences of a major earthquake in the region of one of the world's major cities would be dire.
"As population grows, and it is growing in earthquake-prone regions, we are susceptible to large earthquakes causing huge numbers of fatalities," said Andy Michael, a geologist with the U.S. Geological Survey's Western Earthquakes Hazard Team in Menlo Park, California.
"People do not like to think in terms of an earthquake disaster of 1 million fatalities. Nevertheless, I am convinced this is possible," said Max Wyss, director of the World Agency of Planetary Monitoring and Earthquake Risk Reduction in Geneva, Switzerland.
Brian Tucker, president of GeoHazards International, said his Palo Alto, California-based nonprofit organization was established in 1991 to address "precisely" the type of problems that Bilham suggests are possible.
"Of course, exactly how many people will die in the next large earthquake and how often these earthquakes will occur cannot be known," said Tucker. Regardless, he added, it is clear that the consequences will have a large human, economic, and political effect on the entire world.
Prior to the 17th century, few cities had populations greater than 1 million people, said Bilham. By 1950 there were 43 supercities. Today there are nearly 200 supercities and that number could double before world populations stabilize.
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