“Shake It Off” is one of Taylor Swift’s biggest hit songs. But maybe she should rename it “Shake the Ground.” At two recent Swift concerts, fans got so excited that that’s exactly what they did!

The Earth-shaking events took place in Seattle, Washington, in July 2023. More than 70,000 Swifties (that’s the name for Swift’s fans) gathered each night to watch Swift rock out. During the two four-hour shows, the dancing fans, plus the music, shook the ground as hard as an earthquake.

That’s according to Professor Jackie Caplan-Auerbach, who teaches geology at Western Washington University. (Geology is the study of the features and history of Earth.) Caplan-Auerbach wanted to find out how much the Swift concerts shook the ground, so she checked an instrument called a seismometer, which measures the motion of the ground. Seismometers are often used to measure the strength of earthquakes on a scale of numbers. The higher the number, the stronger the earthquake. The shaking that took place at the Swift concerts wasn’t an earthquake, but the seismometer picked it up. The concert shaking measured 2.3, which is similar to a weak earthquake! 

“The music, the speakers, the beat. All that energy can drive into the ground and shake it,” Caplan-Auerbach told CNN.

After Caplan-Auerbach revealed that she had been studying the effects of the concerts, many of Swift’s fans sent comments to her on social media. They asked her if they had really caused the ground to shake. She said she’s excited to be able to help as many people as possible understand how science connects with real life.

Caplan-Auerbach wants to keep studying those concerts and why they shook the ground. How much shaking did the fans cause? How much of it was caused by the loud music?

Here’s another unanswered question: Is Caplan-Auerbach a Taylor Swift fan? Maybe so!

“I would not be surprised if I came out [of this study] as a Swiftie,” she told CBS News.