SEATTLE — 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 in the first quarter. The game, a 34-7 victory that clinched a playoff berth for the Seahawks, registered on nearby seismic instruments several other times.

John Vidale, director of the Pacific Northwest Seismic Network, said fans get the oval stadium moving back and forth by stomping their feet and jumping up and down. “It’s sort of what you see when a car rocks back and forth,” said Vidale, also a University of Washington earth and space sciences professor.

Vidale said a small quake wasn’t all that surprising in the stadium, which is built on pilings dug through soft ground in earthquake country.

Structural engineers who plan buildings in Seattle often do so with room for movement, so when a natural earthquake happens the buildings aren’t so stiff that they crack and crumble.

Vidale watched the game from his office to compare seismic reports with game action because he wondered if there would be a repeat of the 2011 “Beast Quake,” when Marshawn Lynch ran for a 67-yard, fourth quarter touchdown as Seattle upset the Saints to advance to the second round of the playoffs.

After the 2011 quake, Vidale looked at the whole season and found that that one Lynch run shook the stadium more than any other moment during that season.