Seahawks fans' frenzy felt by seismometer

Seahawks fans literally shook the Earth in their elation over Saturday's upset of the New Orleans Saints.

During the game's pivotal play — Marshawn Lynch's 67-yard touchdown run — the crowd of 66,336 cheered and jumped and stomped so vigorously that the vibrations registered like a small earthquake on a nearby seismometer.

"The stands were shaking," said John Vidale, director of the Pacific Northwest Seismic Network at the University of Washington. "You probably would have felt it very easily if you were outside the stadium."

The energy was roughly equivalent to a magnitude 1 or 2 quake, although the motion was highly localized.

"There was a clear 30 seconds or so of moderate shaking," Vidale said. "It's probably not the first time it's ever happened, but it's the first time we ever noticed."

The seismometer is located on the site of the old Kingdome, where Seahawks crowds first gained notoriety for their noise level. The National Football League later passed a rule that allowed an opposing team to ask a referee to quiet the crowd so the quarterback's signals could be heard by teammates.

Vidale didn't watch Saturday's longshot match against the reigning Super Bowl champs, because he he says he didn't believe the Seahawks stood a chance of winning. But after viewing a YouTube video of Lynch's record-book run the next day, his scientific curiosity was piqued.

"I could see how people were screaming and stomping," he said. "So I wondered if we could see it on our stations."

Like the wonk he is, Vidale also broke the play down into a time series and compared it with the squiggles on the seismogram. As expected, the roar peaked as Lynch broke free and sailed toward the end zone. The subsequent point-after kick and televised replay of Lynch's run both led to detectable aftershocks of enthusiasm.

The Qwest Field crowd may have reached new heights Saturday, but they're not the first sports fans to move earth, and maybe heaven, for their team.

Scientists in Cameroon were baffled in 2006 when their seismic network picked up a series of short, simultaneous spikes across the country. It took them a while to realize each jolt represented a goal scored by the national soccer squad in televised games of the African Cup of Nations.

With the Seahawks headed to Chicago, local seismic stations will get a rest. But if the playoff gods bring the team back to town, Vidale and his colleagues will be on the alert for more man-made rumbles.

Sandi Doughton: 206-464-2491 or sdoughton@seattletimes.com