Seahawks fans rocked the stadium so hard during Monday night's matchup with New Orleans that seismic instruments registered small tremors at various points in the game.
A magnitude 1 or 2 quake was recorded during Michael Bennett's 22-yard fumble return for a touchdown. The game registered on nearby seismic instruments several other times.
Earthquake expert John Vidale says fans get the oval stadium moving back and forth by stomping their feet and jumping up and down.
The director of the Pacific Northwest Seismic Network compared the action to when a car rocks back and forth.
Fans also made record noise Monday, setting the Guinness World Record for loudest outdoor sports stadium noise at 137.6 decibels.
The Seahawks beat the Saints 34-7 to become the first team to clinch a spot in the NFC playoffs.