Destruction and response
So what would the NMSZ look like if a magnitude 7 or 8 earthquake hit? Sprague’s expertise lies in creating building designs that resist blasts or seismic shocks. He examines what happens when ground motions are translated to a building to see how that building would perform. He has developed seismic building codes and has studied the Murrah Building in Oklahoma City, the World Trade Center in New York and the Pentagon in Washington, D.C.
“If it was like 1811 or 1812, we’d see huge amounts of damage—a minimum cost of $32 billion for Memphis alone, according to studies by FEMA,” Sprague says. “There would be major infrastructural losses, pipelines and railroads that cross the Mississippi River would be damaged. The city of Memphis would be hit hard.” Memphis, the most populated city in the NMSZ, would be hard-hit because of the city’s lack of design for seismic energy. Memphis has a large inventory of buildings constructed prior to the use of modern seismic codes. The city didn’t begin to retrofit buildings or build new buildings to a code to withstand a major seismic event until the 1990s.
A few hospitals in Memphis are the notable exceptions: Two hospitals were redesigned, retrofitted or rebuilt using modern seismic design methodology and should weather an earthquake quite well, Sprague says. Some bridges have been rehabilitated, too. But because of the large earth-to-ground motions that could occur, damage in Memphis would still be massive. And the effects on Memphis would be felt in cities that are not directly impacted by an earthquake.
“FEMA studies indicate that Memphis would have to call on all areas, including those that would be relatively undamaged, like Kansas City,” Sprague says. “The hospitals in Kansas City would be maxed out. Most hospitals in the area of Memphis couldn’t take the influx of patients, or the hospitals would be damaged to a degree that they couldn’t handle patients.” Combine the maxed out hospitals with the destruction of buildings, and there’s a potential for a large amount of casualties. Kansas City would be mostly protected, Sprague says, and the ground shaking would not be as severe because of the way the earthquake transmits through the ground to surrounding areas. The Ozark Plateau in southern Missouri acts as a shock absorber between Kansas City and the NMSZ, and it would minimize the movement to the west.
Preparedness and readiness
A look at the sociology of various earthquake-prone areas may reveal why there’s a lack of preparedness in the NMSZ. Sprague compares the NMSZ to the work the state and local government carried out in the Wasatch Fault Zone in Salt Lake City. Once seismologists and engineers predicted what was going to happen there, the community was proactive and began to take measures to mitigate earthquake damage.
The government rebuilt all the bridges prior to the 2002 Winter Olympics and retrofitted the government buildings. Compare that to Memphis, Sprague says, where there has not been that level of effort to rehabilitate the facilities. “It’s to the detriment of that city,” he says. “There’s been some degree of response in St. Louis, but there’s an enormous number of buildings that were constructed without seismic design and the government hasn’t rehabilitated structures to resist the ground motions they’re going to see in St. Louis.” There are many areas in St. Louis where the soil is poor and loose and it will exacerbate the effects of the ground motion on the city.
Sprague says the lack of preparedness is a local cultural issue. “Salt Lake City government is proactive and engaged in the science and engineering community,” he says. “In St. Louis and Memphis, the culture is: ‘What’s this going to cost me?’ They also think, ‘it’s not going to happen in my life here,’ so there’s a myopic view.” Cost is a major factor. It’s expensive to retrofit or rebuild buildings and bridges to withstand a seismic event. But there are studies that show the mitigation is significantly less in cost than the repair and response to such a disaster. “And the cost to human life … it goes without saying,” Sprague says. “The risk is there for a falling building to kill or injure people. We’ve seen that time and again.”