It's not just earthquakes that cause seismic activity. Football fans can also cause quite the rumble.
This weekend, Seattle Seahawks fans were so loud they caused a spike in seismic activity equivalent to a microearthquake.
Seattle Seahawks fans are renowned for their deafening volume. The outdoor stadium has twice held the Guinness World Record for the loudest crowd roar. In 2013 the stadium reached 136.6 decibels and in 2014 it reached 137.6 decibels (a loud rock concert usually gets to be around 120 decibels). That's loud af.
This weekend was no different. On Sunday afternoon, with just 21 seconds to go, quarter back Russell Wilson threw a game-winning touchdown. The crowd erupted, and their cheers were so loud the University of Washington's seismometer picked up the activity.
Seismometers are used by scientists to pick up seismic waves, which are the vibrations from earthquakes that spread through Earth. These readings allow scientists to measure the magnitude of an earthquake.
For instance, a microearthquake has a magnitude of 2 or less and is usually not felt by humans.
Professor John Vidale at the University of Washington confirmed that fans were so loud this weekend it actually looked like one of these microearthquakes had occurred.
"It would probably be the energy of a magnitude-one earthquake; even though the motion was kind of small, it lasted a long time," Vidale told SB Nation.
You can watch the spike in seismic activity here:
This isn't the first time humans have caused seismic activity. Mining operations, fracking, groundwater extraction, dams and power plants can all cause a certain amount of ground activity.
This isn't even the first time that football fans have been picked up by a seismometer. In 2013, when the Seahawks scored a touchdown from a fumble, the fans caused a similar disturbance.
While no one doubts how loud Seattle fans can be, these microearthquakes say more about the location of the stadium than the volume itself.
The University of Washington's seismometer is located just one block away from the Seahawks' stadium. That's like screaming into a megaphone and wondering why your voice is so loud.
Even still, the touchdown was an earth-shattering moment for Seahawks fans.