Taylor Swift's Seattle concert caused the ground to shake like a small earthquake

Taylor Swift fans are shaking the ground while they're shaking it off at her The Eras Tour concerts.

A seismologist recently discovered that fans attending Swift's recent concert in Seattle on July 22 and 23 danced so hard that, combined with the sound system, they caused seismic activity that could potentially be compared to a 2.3 magnitude earthquake.

Jackie Caplan-Auerbach, a seismologist and geology professor at Western Washington University, tracked the seismic activity from the concert and discovered the movement caused by the Swifties broke the previous record of movement at Lumen Field.

Before Swift's concert, the most seismic activity at the stadium was the "Beast Quake," which occurred in 2011 and was caused by Seattle Seahawks football fans celebrating after running back Marshawn Lynch scored a touchdown. At that time, experts hypothesized that the shaking could have been comparable to 2.0 magnitude earthquake.

Caplan-Auerbach said she decided to chart the activity after someone asked in a Facebook group if Swift's concert had beaten the "Beast Quake," knowing that there is a seismometer located near the stadium that picks up ground movement.

According to Caplan-Auerbach, the magnitude difference between the "Beast Quake" and the "Swift Quake" was 0.3, but the shaking was twice as strong as "Beast Quake."

"The other thing is that the 'Beast Quake' was a moment in time, you know. It was maybe 20, 30 seconds of incredible crowd joy and celebration and ground shaking, whereas the Taylor Swift concert was hours of this," she said.

Caplan-Auerbach said she tracked the seismic activity from both nights of Swift's concert and found that the activity was relatively the same.

She said she contributes this to the setlist being the same except for the two surprise songs that Swift plays. At each concert, Swift chooses two songs that are not on the setlist and she has not played during The Eras Tour to perform for her fans.

In the future, Caplan-Auerbach said she plans to chart what the seismic activity looked like in Seattle at the time Swift played her surprise songs each night and see if they are different based on the changing songs.

"Given that the setlists were the same for most of the concert, I know they should be similar. The waveforms, the wiggles should be the same for most of those songs, but they should be different for the surprise songs. So that's one of the hypotheses that we can test," she said. "It'll confirm for us whether what we're seeing is unique to a given song. If that portion of the concert is different between the two nights."

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Are the stadiums supposed to shake?

Whether you're at a Swift concert or a different event in a stadium, don't be alarmed if the building begins to move.

Matt Breidenthal, director of engineering at the design, architecture, engineering and planning firm HOK, told USA TODAY that its completely normal and safe for stadiums to shake or move when there are a lot of people inside it.

Every building should be able to move if there is push or pull applied to it, but the movements will not always be noticeable, he said.

"In most cases throughout the day, you don't notice it because it's so small and incremental that it's not worth mentioning or talking about, but then you do have events like this, like a concert or an earthquake. But there's a lot of other ones, like big high wind events," Breidenthal said.

Structures like stadiums and skyscrapers are designed to withstand movement much greater than the "Beast Quake" or the "Swift Quake," he said.

"We designed for seismic events that are tens of thousands of times more powerful than a 2.3 [magnitude event]. Like if you go up to three or four or five, all of a sudden, you're 10,000 times more powerful than that Taylor Swift concert," Breidenthal said.

He added that engineers work to determine how much movement a building can have while still keeping the viewers inside of it comfortable if it does in fact move.

Breidenthal said the engineers use computer models to determine how much a building might move depending on the number of people in the building, how much they weigh, how close together they are and more to see how those factors will impact the structure.

Additionally, for large and complex projects, multiple types of engineers and the city where the structure is being built in check the building.

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While it may be uncomfortable that the stadium or building you are in is moving, Breidenthal said it is important to remember that the structure is purposefully designed that way.

"We're talking about the stadium and people jumping up and down and it moves a little bit under that and that might be counterintuitive, but you look at any skyline and downtown and each one of the towers moves back and forth by inches and in some events, it can be a foot or two and it's totally fine," Breidenthal said. "In that instance, it's very similar what we're talking about here, which is that the building is perfectly strong enough and rigid enough to go under that amount of movement."

Have stadiums shaken before?

Swift's concerts are not the first to move stadiums. Other events have also resulted in people shaking the ground as they move excitedly.

At a 2011 Foo Fighters concert in Auckland, New Zealand, the dancing of fans likely caused vibrations recorded throughout the duration of the concert.

In May 2022, fans at a Garth Brooks concert in Louisiana caused vibrations recorded as a "small earthquake."

Additionally, fans are not the only factors that can shake stadiums. At a May 2016 Bruce Springsteen concert in Barcelona, Spain, the music from the speakers sent sound into the ground, which in turn resulted in vibrations.

The Eras Tour is nearing the end of its U.S. leg. Swift takes the stage next at Levi's Stadium in Santa Clara, California, on July 28 and 29.

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Contributing: Dinah Voyles Pulver