The man behind much of the shaking, Marshawn Lynch, and Seattle fans celebrate the Seahawks' NFC divisional playoff win against the New Orleans Saints. Browse our earthquake image gallery.

© Joshua Weisberg/Icon SMI/Corbis

Residents of the Pacific Northwest are no strangers to earthquakes. The area is virtually crawling with fault lines, not the least of which is the Cascadia subduction zone, where the Juan de Fuca plate meets the North America plate and then heads below it.

Somewhat less familiar to Northwesterners are championship sports teams. As of January 2014, Seattle was home to only one championship team in the last 35 years: the WNBA's Seattle Storm. So what are the chances that surprised and delighted Seattle Seahawks fans celebrating a victory don't just coincide with seismic activity but actually cause it?

According to the Seattle fans, it's obvious. They've christened the events "Beast Quakes," after running back Marshawn Lynch's 2011 touchdown run against the New Orleans Saints, which propelled the team to the playoffs. (Lynch's nickname is Beast Mode.) During and after the run, the Pacific Northwest Seismic Network reported activity on its station a block away from the Seahawks' CenturyLink Stadium. The acceleration (or the largest increase in velocity) reached 1/20,000th of a g, and peak motion of about 1/100th of a millimeter [source: Vidale]. According to the U.S. Geological Survey, seismologists measure the forces caused by the shaking as a percentage of gravity, or g. You'll typically see the amplitude of the seismic waves measured in millimeters. The USGS adds that you can think of amplitude as the size of the squiggly lines on an earthquake recording.

But were Seattle fans really behind this seismic swaying? When the Seahawks qualified for the playoffs in 2013/2014, the Pacific Northwest Seismic Network was even more prepared to answer the question. They placed two (and later three) portable seismographs inside the stadium to record if the good vibrations were coming from the fans.

The answer was pretty clear: Seahawks fans were causing seismic activity on big plays or wins. Now remember that seismologists aren't measuring the volume of the 12th Man in the stadium -- that's what the fans in attendance have collectively dubbed themselves. While the fans at the stadium set a Guinness World Record for decibel level in 2013 (137.6 decibels!), it's the movement of people jumping up and down, waving their arms and generally creating vibrations that scientists are measuring and recording [source: Seattle Seahawks].

Let's check out the next page for a little more in-depth analysis of how these small quakes are caused and measured, and see if fans actually could contribute to a major earthquake.