Tsunamis are one of the most devastating natural disasters known to coastal mankind. A tsunami involves the whole body of water moving – unlike a normal wave, which skips over the water surface – and they are not rare. Capable of forming in any sea in the world, including lakes and the Mediterranean, an average of about two of these mega waves develop worldwide each year – though each region has its own typical frequency – and no force on Earth has been thought capable of stopping them.
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Dr. Usama Kadri isn’t a force. He’s a mathematician from Cardiff University in Wales, and he has a theory that tsunamis could be halted in their watery tracks using sonar.
Around half a million human lives have been lost to these juggernaut waves over the last 20 years, Kadri writes in a paper published this week in the research journal Heliyon.
Specifically, Kadri proposes to fire deep-ocean sound waves (what he calls acoustic-gravity waves) at the oncoming mass of water. We don’t know how to create such sound waves yet, but it is a thought that may count one day.
“The main tsunami properties that determine the size of impact at the shoreline are its wavelength and amplitude in the ocean,” he explains. He proposes to reduce the amplitude of tsunamis by redistributing the energy over a larger space. How? By forcing the wave to interact with resonating acoustic-gravity waves.
Major tsunamis are usually triggered by undersea earthquakes, eruptions and landslides, or meteor impacts on water.
For instance, the tsunami that inundated Fukushima and its nuclear reactor in March 2011 was caused by a massive, magnitude-9 temblor just off the coast of Japan. Additional quakes have rocked that area since, though none of that size.
The acoustic-gravity waves on which Kadri’s theory is based are massive, naturally occurring sound waves that move through the deep ocean at the speed of sound. They can travel thousands of meters below the surface, and can measure as much as hundreds of kilometers in wavelength.
So, if science can find a way to engineer these deep-ocean sound waves and fire them in a specific direction, they could theoretically react with the incoming tsunami in such a way that reduces its amplitude (wave height), causing the energy to be dissipated over a large area.
The tsunami would reach shore, make no mistake, but as a shrunken beast of reduced height that should cause less damage.
Or, theoretically, Kadri proposes that the sound waves could be repeated until the tsunami is completely dispersed.
Or maybe natural sound waves could be harnessed somehow. That is as theoretically possible as us generating powerful enough sound waves for the tsunami to even notice: even if we figure out how to do it, it’s going to take a lot of energy.
Kadri has already demonstrated that naturally occurring sound waves can be utilized in early tsunami detection systems. Early detection of a forming tsunami would be crucial to any effort to mitigate its effects.
Kadri’s concept can’t be developed a moment too soon for the Mediterranean basin area, which has recently learned that the supervolcano squatting on Italy’s “boot” has been showing signs over the last 15 years or so of waking up (though a volcanologist reassures Haaretz that, based on the data of scientists studying the volcano, any eruption isn’t likely for decades).
An eruption by Campi Flegrei would definitely cause a tsunami that could wreak devastation on coasts around the region, though Israel should be relatively spared because of its geographical protection by Malta and Italy’s boot.