Taylor Swift's fans caused such a stir at her Eras Tour gigs in Scotland over the weekend that seismologists recorded tremors nearly four miles away.
Some 220,000 people turned out to see the American pop icon at the Murrayfield Stadium in Edinburgh between Friday and Sunday, averaging 73,000 each night.
And as the 34-year-old headed north for her UK dates, Swifties showed their appreciation by dancing and stamping loud enough for the British Geological Society to pick up minor movements on the ground.
'If you can imagine, you have 73,000 people in one concentrated place — jumping, clapping, dancing,' said Sophie Butcher, an Edinburgh volcanologist who was in the crowd on one of the dates.
'As well as that, there's a big bass sound system. All of that energy travels through the ground,' she said, as reported by The Times.
The British Geological Survey (BGS) was able to record minor measurements by overlaying similarities in movements night to night.
They said her choreographed performance was similar enough between the dates that they could clearly discern noise from the concerts from the noise of the wider city.
Taylor's 2017 hit Ready For It recorded the loudest response across the nights, played just before 8pm.
Cruel Summer, coming much earlier in the set, also recorded a relatively large response, though came to about half of Ready For It.
Champagne Problems and global hit Shake It Off were also recognisable from their seismological signatures.
Still, the fans' activity was not enough to give the BGS a clear reading on the earthquake magnitude scale.
Butcher said the ability to record 73,000 people 'jumping and dancing to their favourite songs' at such a distance was nevertheless 'impressive'.
The concerts created an electric atmosphere around Scotland's largest stadium, the home of the country's national rugby team.
Public transport in the city was forced to run at an increased capacity over the weekend to take the tens of thousands of Swifties to and from the concert venue.
And fireworks have lit up the sky above Murrayfield as Taylor Swift draws the opening night of her Eras Tour in the UK to a close.
On June 7, Taylor even hinted she would return to Scotland to huge cheers from the crowd.
She told the crowd: ‘This has been the most insane thing. We have to do this again!
‘My biggest regret is that I should have played in Scotland more. I should have brought every tour to Scotland.
'I can’t stop looking at the crowd…it’s captivating.’
Taylor Swift will play Wembley Stadium in London on June 21, following dates in Liverpool on Thursday and Friday.
