Science

Could blasts of sound stop a tsunami?

Could blasts of sound stop a t...
Acoustic Gravity Waves could theoretically be used to mitigate the effects of tsunamis
Acoustic Gravity Waves could theoretically be used to mitigate the effects of tsunamis
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Acoustic Gravity Waves could theoretically be used to mitigate the effects of tsunamis
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Acoustic Gravity Waves could theoretically be used to mitigate the effects of tsunamis

On December 26, 2004 at 00:58 GMT, an earthquake occurred in the Indian Ocean off the west coast of the island of Sumatra. In a single second, many megatons of explosive force were released in the seabed, triggering a series of tsunamis that devastated the coasts of 14 countries and killed up to 280,000 people. Such an act of nature may seem like something that we can only endure and clean up after, but Dr. Usama Kadri of Cardiff University's School of Mathematics believes that it may one day be possible to use acoustic-gravity waves against tsunamis to mitigate or even halt their effects.

Tsunamis are produced by seismic events like earthquakes or underwater landslides; they are ocean shock waves that are thousands of miles long and can span from one continent to another. At sea, they are barely perceptible as ships rise and fall safely at their passing, but when they encounter the shallower waters near land, they turn into deadly aquatic juggernauts that can destroy whole cities and inundate entire regions.

One characteristic of tsunamis is that they generate acoustic-gravity waves (AGW), which are compression waves modified by gravity. Previously Kadri has said he hopes to use such waves that travel through the deep ocean to gain a better understanding of tsunamis and even provide an early warning system of their approach, but now he wants to go one better and use AGWs to combat the tsunamis themselves while they are still far out at sea.

Much as sound waves can be used to combat unwanted sounds in noise-dampening headphones, Kadri's idea is to fire AGWs at incoming tsunamis and disrupt their waveforms to reduce their amplitude. This way, when one reaches shore, the tsunami will be much less powerful and cause much less damage. In fact, if the artificial AGWs could be sent in a series of pulses, it might even be possible to completely disperse a tsunami in midocean.

It's a reassuring vision, and one Kadri worked out mathematically, but he points out that it's very much in the theoretical stage and a long way from practical application – or even demonstrating that it's feasible. To produce such a counter-tsunami system it will first be necessary to build a deep-ocean detector network to track and analyze tsunamis, so a proper anti-tsunami pulse can be configured. Even if this was possible, to generate such AGWs would require sonic transducers of tremendous size and each capable of handling the force equivalent to a nuclear warhead.

"In practice, generating the appropriate acoustic-gravity waves introduces serious challenges due to the high energy required for an effective interaction with a tsunami," says Kadri. "However, this study has provided proof-of-concept that devastating tsunamis could be mitigated by using acoustic-gravity waves to redistribute the huge amounts of energy stored within the wave, potentially saving lives and billions of pounds worth of damage."

The research was published in Heliyon.

Source: Cardiff University

10 comments
Jesse Gunn
Even if this is possible with the right engineering, the resulting pressure wave would kill an incredible amount of aquatic life and anything within a few miles of the resonator. This is one of the stupidest ideas I have ever heard. Not to mention combining acoustic and gravity into a wave. Acoustic wave sure. Gravitational waves are you kidding me?!
Jerry Peavy
Stop a tsunami and kill vast amounts of sea creatures at the same time, what a great idea!
VincentWolf
No but a few well placed nukes could do the job. Unfortunately they might do even more damage than the tsunami!
McDesign
How could the wave be "cancelled" without an equivalent force?
Bob Flint
Equal force required at the location in the right orientation, seems improbable to say the least.
Similar to planning to stop or re-direct an asteroid we don't know where or when.
Why not just stay clear of the high risk shorelines....
GregElmassian
Kind of a misleading definition, of course the acoustic wave is modified by gravity in the ocean, because the wave is moving through water and the water is affected by gravity....
But the big comment is you can create a multi-megaton underwater blast, and direct it all towards the incoming wave?
That will require a nice dance with the laws of Newtonian motion, the only way you make explosions directional is putting something that cannot move behind them (even if it is more explosive material)... so you would build an enormous bulkhead underwater to direct the multimegaton explosion away from the shore? How do you know where it place it? Oh, just build it along the entire coastline.
I feel badly that someone's tuition went up just to pay for someone figuring out that an unbuildable bomb could stop a tsunami. Gee, I could probably stop the sun from going supernova in the future by building a giant C clamp to go around it and keep it from expanding.
guzmanchinky
For how rare an event a tsunami is, I think this would never get funding.
RustyZahn
I think this sounds like a great idea, if the sound wave is made oboe water I can't see how it would affect any sea life, it's definitely worth looking into
Bob
It would be just as easy to defuse the earthquake that caused the tsunami. Did I just say easy? Never mind.
TominCA
Unfortunately, this could also be used as a weapon, especially if there were multiple sites. Probably not a good idea.