Ground-thumping cheers help scientists

Earthquakes aren’t the only things that rattle the U.S. Pacific Northwest. And that’s a bonus for researchers looking for new ways to test quake sensors.

Fans of the Seattle Seahawks are notoriously loud and crazy. That is especially true when this football team is enjoying a winning season. After a stunning touchdown in the 2011 NFL playoffs, the crowd’s roars shook the Seattle stadium. Those vibrations also shook the surrounding ground.

Later, scientists analyzed recordings made by a seismic sensor. The instrument was located just across the street from the stadium. “We saw a clear signal,” remembers John Vidale. He studies earthquakes at the University of Washington in Seattle.

The energy of 70,000 fans jumping around for a minute could come close to the energy released by a small earthquake, Vidale now estimates. It occurred to him and other researchers that athletic events might be a good way to test seismic instruments. Indeed, one benefit: Football games, unlike earthquakes, happen on schedule. These experiments also are “a lot more fun” than running tests in a lab basement, he adds.

Vidale and coworkers got busy just before the January 2015 NFL playoff games in Seattle. The experts installed three portable sensors inside the Seahawks’ home stadium. Unlike in 2011, the strongest signal didn’t show up during a game-changing play. Instead, the greatest shaking coincided with the crowd’s jumping and dancing during the halftime show. (They had been moving in sync with Macklemore & Ryan Lewis’ hip-hop tune, “Can’t Hold Us.”)

One goal of the stadium experiment was to practice installing and collecting data with improved seismic sensors. Also new in 2015, the researchers developed software to display the seismic recordings with a delay of just a few seconds. That is less than the 10- to 15-second time lag built into the game’s televised broadcast.

Fans watched the display, called QuickShake, on the web during the playoff games. “People could see the crowds go crazy and then watch the players on TV hiking the ball,” Vidale says.

Power Words

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earthquake    A sudden and sometimes violent shaking of the ground, sometimes causing great destruction, as a result of movements within Earth’s crust or of volcanic action.

seismic   Adjective for something having to do with the ground movements associated with earthquakes.

seismic wave  A wave in the ground produced by an earthquake or other means.

seismometer (also known as a seismograph)  An instrument that detects and measures tremors (known as seismic waves) as they pass through Earth.

seismology  The science concerned with earthquakes and related phenomena. People who work in this field are known as seismologists.

sensor  A device that picks up information on physical or chemical conditions — such as temperature, barometric pressure, salinity, humidity, pH, light intensity or radiation — and stores or broadcasts that information. Scientists and engineers often rely on sensors to inform them of conditions that may change over time or that exist far from where a researcher can measure them directly.

software  The mathematical instructions that direct a computer’s hardware, including its processor, to perform certain operations.

vibrate  To rhythmically shake or to move continuously and rapidly back and forth.