What Constitutes Acceptable Earthquake Risk?

According to seismologists, major New Madrid earthquakes are rare. When one eventually occurs, however, it can be catastrophic. So how do small towns that line the New Madrid fault zone improve earthquake preparedness when immediate risk and awareness are low and town budgets are stretched?

"Unfortunately earthquake safety in the Midwest is event driven -- most people will not begin to care about the risk until an earthquake happens," says David Gillespie, Ph.D., disaster preparedness expert and professor of social work at Washington University in St. Louis. "Town leaders need to think long-term -- 25 or 50 years out -- about incremental improvements in safety measures that can be sustained. This is a different kind of planning, but it is necessary to be ready for the eventual catastrophic quake that will strike."

Gillespie presented the paper, "Dyanmics of Earthquake Safety and Economic Development," on Feb. 20 at the annual meeting of the American Association for the Advancement science, held Feb. 16-20 in St. Louis.

In his study, Gillespie and colleagues examined 15 years of data from a small Southern Illinois town to see whether it was possible to promote both earthquake safety and economic development.

"We used the Applied Technology Council's ATC-21 measure of seismic building safety to compare earthquake safety to the town's economic development," Gillespie says.

"We looked at the fraction of safe buildings and the fraction of new and retrofitted buildings in the town. Using conflict theory, we hypothesized that competing goals would fight for resources. After looking at the baseline data, we found that, as predicted, the concern for earthquake safety decreased as the push for economic development increased."

Using the same measures, Gillespie and colleagues simulated the comparison for the next 30 years, from 2004-2034.

"Interestingly, the inverse relationship found in the first 15 years disappeared within the first few years of the simulation. Both the push for economic development and earthquake safety ended up decreasing by the end of the simulation," he says.

Gillespie and his colleagues began looking for policy parameters to reverse this trend. They found that the town could increase safety for the community by encouraging the tearing down of old buildings as new buildings were constructed. In addition, by making other policy adjustments such as adding a few hundred acres of land to the town, the researchers found it was possible to spur both earthquake safety and economic development.

This study is important for small towns in the Midwest because it shows that community safety tends to deteriorate with typical short-term, event driven planning, but also because it shows that economic development and safety are not necessarily competing goals. Improving community safety is good for economic development.