New research from the University of Arkansas finds that tornadoes cause greater damage when traveling uphill — and that the twisters tend to climb toward higher elevations rather than going downhill.
Engineering researchers studied images of the 2011 deadly tornadoes in Tuscaloosa, Ala., and Joplin, Mo. The research team, which found similarities between the two tornadoes, say the findings likely apply to all tornadoes and that their work could influence building patterns.
“We wanted to understand the impact of terrain on damage magnitude and tornado path,” said Panneer Selvam, a professor of civil engineering. “Information about this interaction is critical. It influences decisions about where and how to build, what kind of structure should work at a given site.”
Researchers found that when a region is surrounded by hills, tornadoes often skip or hop over the valleys below.
An EF4 tornado in Tuscaloosa in April 2011 killed 64 people, while the EF5 Joplin twister a month later killed 158 people.
Selvam and graduate student Nawfal Ahmed laid tornado coordinates from the National Oceanic and Atmospheric Administration over Google Earth images and compared historical images to aerial photographs taken after the storms.
They said the data clearly showed more damage as the tornadoes went uphill.
With both the Joplin and Tuscaloosa tornadoes, there were several locations where the paths changed direction. At each of these locations, or intersections, the tornadoes consistently sought higher ground.