“I grabbed 10 hours of data, from when doors opened to well after I thought the audience had gone home, and I just plotted them out to see how did the ground shake,” she told Seattle’s King 5 news.

Seismic data showed that the activity generated by Swift’s “Eras” tour concert at Lumen Field was comparable to a similar “Beast quake” in 2011, set off by Seattle Seahawks football fans after a touchdown by Marshawn “Beast Mode” Lynch, Caplan-Auerbach said, although she added the caveat that the two events were different, making direct comparisons difficult.

“I don’t really want to get into a snickering match between Seahawks fans and Swifties, but I will say Swifties have it in the bag,” she said. “This was much bigger than the Beast Quake in terms of the raw amplitude of shaking, and it went on for a whole lot longer, of course.”

Fellow seismologist James Hammond, a professor of geophysics at Birkbeck, University of London, said in an interview that it’s actually “quite common” for humans partying to create such vibrations, sending “a lot of energy into the ground.” That energy travels as sound waves through the Earth, he said, and is measured using sensitive seismometers.

“A 2.3-magnitude earthquake is quite small though, so I expect it would only be felt quite close to the concert,” Hammond said, noting it would not have caused any damage, due to the “relatively small amount of energy released.”

Similar spikes occur at music festivals and sports matches, he added. During the coronavirus pandemic, vibrations from human activity were “reduced markedly” around the world during lockdowns and social restrictions.

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At least one of Swift’s sold out Seattle concerts reportedly broke the attendance record at Lumen Field, which has a capacity of about 72,000 people.

Although no specific song was responsible for the vibrations, it’s likely that together the booming sound system and the cheering, stamping and dancing of fans caused the activity, experts say.

“I collected about 10 hours of data where rhythm controlled the behavior. The music, the speakers, the beat. All that energy can drive into the ground and shake it,” Caplan-Auerbach told CNN.

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Swift has not publicly acknowledged the seismic activity but posted on social media that the Seattle concerts were very lively.

“Seattle that was genuinely one of my favorite weekends ever,” she said. “Thank you for everything. All the cheering, screaming, jumping, dancing, singing at the top of your lungs.”

Tarje Nissen-Meyer, a geophysicist at the University of Oxford, said in an interview that the vibrations were unsurprising and “basic physics.”

“Vibrations from all sorts of sources continuously excite the earth,” he said. “Having tens of thousands of Swifties dancing in sync then induces a sizable vibrational force onto the ground,” he added, using a common nickname for her fans.

Currently, seismic waves are used to study landslides, ocean weather, glaciers and traffic, among other things. However, with the improvement of high-precision seismic instrumentation, Nissen-Meyer said, it could be the case that we hear of more such social events detected in the future.

“Much like we can deduce different earthquake types, one could perhaps discern a Taylor Swift gig from a Bad Religion one, some day. It all depends on the amount of data recorded and processed,” he said, noting that he personally favors a different genre of music but recognizes Swift’s “huge talent.”

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Swift’s U.S. tour is now in California, and she heads to Mexico in late August. There has been unprecedented demand for concert tickets across the globe, sparking headlines, political debates about ticket operators, and a stream of shared frustration and jubilation on social media among her loyal fans.

The next major artist to play at Lumen Field will be Beyoncé in September, and geologist Caplan-Auerbach tweeted that she was busy working on a “proposal to get tickets,” in a bid to compare the two events. “For science,” she added.