Sound waves could take a tsunami down a few notches

Acoustic-gravity waves would exchange energy with destructive water wave

2011 Japan tsunami

WAVE GOODBYE  Firing a pair of sound waves at a tsunami, like this one that hit Japan in 2011, could weaken the wall of water and decrease its height, a researcher proposes.

Mainichi Shimbun/REUTERS

A tsunami’s immense wall of water may not be stoppable. But there may be a way to take the ferocious force of nature down a few notches, using a pair of counterwaves.

If released at the right moment, a type of sound wave known as an acoustic-gravity wave could subdue a tsunami, applied mathematician Usama Kadri of Cardiff University in Wales reports January 23 in Heliyon. These acoustic-gravity waves, which reach deep below the ocean’s surface, can stretch tens or hundreds of kilometers and easily travel long distances at high speeds.

In Kadri’s plan, two acoustic-gravity waves would be launched through the water at the earthquake-triggered ocean surge. The waves would be tuned to exchange energy with the tsunami as they speed past, spreading the tsunami out by redistributing its energy and thereby decreasing its maximum height.

The tsunami sapper is still theoretical — scientists don’t yet have a way to create the high-energy waves needed. But Kadri suggests his approach could have shrunk the amplitude of the devastating 2004 Indian Ocean tsunami by almost 30 percent. Such a reduction translates to a five-meter decrease in the height the water reached above sea level, enough to potentially save lives and property.

Physics writer Emily Conover has a Ph.D. in physics from the University of Chicago. She is a two-time winner of the D.C. Science Writers’ Association Newsbrief award.

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