With every yard Seahawks running back Marshawn Lynch gained, Qwest Field got louder and louder and louder.
By the time his 67-yard, eight-tackle-breaking scamper in Saturday's playoff game against the New Orleans Saints was over, the 12th man was rocking.
And apparently so was the earth below the stadium.
The Pacific Northwest Seismic Network recorded a small tremor at exactly 4:43 p.m. Saturday afternoon from an old monitoring system near where the Kingdome used to stand.
That time is almost exactly when Lynch broke what turned out to be the game-deciding touchdown run in the 4th quarter, sealing the improbable win by the Seahawks.
And while Qwest Field is famous nationwide for its crowd noise, PNSN scientists think their readings show that was the first recorded 12th man tremor, ever.