The power of… celebration.
After setting a Guinness World Record for noise at an outdoor stadium in September, CenturyLink Field went seismic during Monday Night Football, registering as an earthquake at a recording station about a block from the stadium.
How big, you ask?
In the magnitude 1-to-2 range, according to John Vidale, a professor at the University of Washington and the director of the Pacific Northwest Seismic Network.
Five separate events during the game were large enough to register. The biggest was a first quarter touchdown. This is not such a rare event. When sports stadiums of this size are full to capacity, they become equivalent to the population of a city in a rather small area. When lots of people get excited and jump up and down all at once, it will vibrate the earth and transmit that vibration, naturally. Mine blasts or collapses can register as earthquakes, major explosions may also. During the Reason Rally in 2010, Adam Savage of Mythbusters asked everyone to jump at once to see if it registered on an adjacent seismograph. Sadly, the crowd was so huge, we all couldn’t hear his directions. But, if I recall correctly, the needle bounced.