Not to be outdone, this year the Texas Motor Speedway asked seismic experts from Southern Methodist University in Dallas to record the Duck Commander 500 race. It's a typical NASCAR race, with 43 stock cars roaring around a 1.5-mile track and twice the number of fans as a Seahawks game.
"The owner wanted to be able to say his race had larger ground motions than the Seattle Seahawks," joked Brian Stump, a seismologist at Southern Methodist University and co-leader of the project. More seriously, Stump and other scientists are interested in monitoring large crowds with seismic and acoustic signals transmitted through the earth and the air. And large structures such as stadiums, bridges and tunnels have natural frequencies that can change when something is amiss, such as unwanted cracks. As such, monitoring the vibrations is a way to detect unseen damage to these imposing structures.
On April 7, 2014 – a day late due to rain – a network of listening devices installed on volunteer time by Stump and his students and colleagues switched on both inside and outside the racetrack stadium. The instruments were set up to record everything from infrasound, or sound below human hearing, to explosion-level noise, and from earthquake-strength shaking to the weakest tremors. So who rocks hardest? It turns out it's not a fair contest.
"[NASCAR] is apples to oranges from a Seahawks game," Stump told Live Science. "It's a completely different phenomenon." The defining moments of a football game – touchdowns, interceptions, kickoffs and more – get fans on their feet in unison, creating a powerful force that rocks the stadium. But a NASCAR race is an endurance event, without much beyond crashes to bring the crowd together on their feet. No seismic signals came from the crowd during the race, Stump reported. Instead, the strongest vibrations were between 20 hertz to 100 hertz, five times higher in frequency than the signals seen at a Seahawks game, Stump said. These tremors came from the racecar engines, he said. Their deep bass rumbling made the ground vibrate, called acoustic-to-seismic coupling. Yahoo Sports