Newswise — A major earthquake in the New Madrid seismic zone could affect the movement of emergency vehicles and other first response teams into and out of stricken areas if steps aren't taken immediately to prepare bridges and other transportation infrastructures, says a team of University of Missouri-Rolla researchers.
"Our nation's highway transportation network physically connects airports, train stations, harbors and manufacturing plants, as well as fire stations, hospitals, police and military headquarters," says Dr. Genda Chen, associate professor of civil engineering at UMR. "This transportation network must continue to function during and after a devastating natural hazard event, such as an earthquake, so that the lifelines of our society can be repaired or restored in a timely fashion and emergency facilities can be used for event rescue operations immediately after the event."
In a report to be released Sept. 15, researchers in UMR's Natural Hazards Mitigation Institute (NHMI) detail the potential impact a major earthquake along the New Madrid Fault would have on the bridges and highways of southeast Missouri and the St. Louis area. Commissioned by the U.S. Federal Highway Administration, the study represents the first systematic investigation in the vicinity of the New Madrid seismic zone involving seismologists, geologists, geotechnical and structural engineers, and economists, says Dr. Neil Anderson, professor of geological sciences and engineering at UMR and director of the NHMI.
The New Madrid fault is an active seismic zone that includes southeast Missouri and extends into southern Illinois, northeast Arkansas, and parts of Kentucky and Tennessee. The fault derives its name from the Great New Madrid Earthquake of 1811-1812, which occurred along this fault line. According to experts, the highest earthquake risk in the United States outside the West Coast lies along the New Madrid fault.
"If an earthquake similar to the ones in 1811-1812 strikes the New Madrid seismic zone, many nearby transportation structures will collapse or be rendered unusable," Chen says. "Even a slightly lower magnitude earthquake, say 7.5 on the Richter scale, would cause extensive liquefaction within many proximal bridge foundations and approaches, and result in unstable and unusable bridges. The substructure of many bridges would also incur substantial damages."
Although ground shaking at bedrock in the vicinity of the New Madrid fault for a given magnitude earthquake is estimated to be stronger than predicted by current models, this energy is now believed to decrease more rapidly with distance than previously thought.
"This implied that bridges far away from the fault will require less strengthening than what was recommended by engineering community prior to the current study," Chen adds.
This study also demonstrates the effectiveness of fiber-reinforced polymer wrapping for reinforced concrete columns through laboratory tests of large-scale structures. In addition, researchers developed a new technology with thin steel sheet wrapping that can provide a rapid construction but reliable technology for column strengthening.
A major earthquake could be catastrophic for the St. Louis metropolitan area, with damage and economic direct losses potentially reaching $70 million to $800 million.
Other NHMI contributing members include Dr. Ronaldo Luna, associate professor, Dr. Pedro Silva, assistant professor, and Dr. Richard Stephenson, professor. All three are members of the civil, architectural and environmental engineering department at UMR.
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