Seahawks fans cause small quake during Saints game

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.

He said it’s possible quakes occur in stadiums in other cities,

but he suspects Seattle’s stadium is more flexible than most and

may flow with the fans more.

”People unconsciously get the stadium moving, sort of like the

wave,” he said.

Seattle structural engineer John Hooper said similar quakes can

happen anywhere a large number of people are moving in unison, but

the difference in Seattle is that there were instruments nearby to

record the quake and people were paying attention.

The same thing could happen next weekend in San Francisco, when

the Seahawks play the NFC West-rival 49ers, said Hooper, director

of earthquake engineering at Magnusson Klemencic Associates.

But he also acknowledged Seahawks fans are unique.

”They’re very enthusiastic and it shows,” Hooper said.

Seattle fans also made record noise Monday, setting the Guinness

World Record for loudest outdoor sports stadium noise at 137.6

decibels.

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Online:

Seismic reading from Monday’s game:

http://pnsn.org/seismogram/current/kdk