What Kinds of Seismic Signals Did Swifties Send at LA Concert?

13 March 2024–Seattle may have experienced its own Swift Quake last July, but at an August 2023 concert Taylor Swift's fans in Los Angeles gave scientists a lot of shaking to ponder.

After some debate, a research team led by Gabrielle Tepp of Caltech concluded that it was likely the dancing and jumping motions of the audience at SoFi Stadium—not the musical beats or reverberations of the sound system—that generated the concert's distinct harmonic tremors.

One of the goals of the research team was to find a way to extract the concert's tremor signals from spectrograms. Spectrograms are graphs that display the strength of various signal frequencies over time. They are often used to display frequencies of sound waves, but they can also help seismologists visualize signals recorded by seismometers and other instruments.

For Tepp, who has studied volcanoes and is also a musician, the concert data was a great opportunity to test methods for detecting seismic signals in spectrograms. "For earthquakes, most of the time they're pretty sharp and easy to identify with waveforms, but when you have something like volcanoes where you have such a wide variety of signals, spectrograms can be really handy in helping to identify the different types of signals," she explained.

The experimental data confirmed that it was motion and not music that was creating the harmonic tremor. "Even though I was not great at staying in the same place—I ended up jumping around in a small circle, like at a concert—I was surprised at how clear the signal came out," Tepp said.

Read the full article here SSA.