Study: Seismic signals linked to tornadoes BLOOMINGTON, Ind., March 8 (UPI) -- U.S. scientists say they detected seismic signals associated with tornadoes that hit the Midwest last week, a finding that may aid future tornado predictions. Such seismic indications could have value for meteorologists studying the atmospheric activity that precedes tornado disasters, they said. An experiment by Indiana University involved more than 100 state-of-the-art digital seismographs located in a broad swath of the U.S. Midwest, and one of the tornadoes that struck southeastern Missouri and southern Illinois Feb. 29 passed through the seismic detection array, the university reported Thursday. "In examining the seismograms, we recorded unusual seismic signals on three of our stations in southern Illinois," researcher Michael Hamburger, a professor of geological sciences, said. "The seismograms show a strong, low-frequency pulse beginning around 4:45 a.m. on Feb. 29," he said. Our preliminary interpretation, based on other seismic records of tornadoes, suggests that we were recording not the tornado itself, but a large atmospheric pressure transient related to the large thunderstorms that spawned the tornadoes. Such pressure-related signals may help scientists better understand atmospheric activity that takes place right before tornadoes touch down, he said.