Scientist's Anti-Wave Guns Could Shrink Tsunamis By 30 Percent


Robin Andrews

Science & Policy Writer

The spread of the 2011 Tohoku tsunami, with redder colors representing higher wave amplitudes. PacificTWC via YouTube

Within the last 20 years, 500,000 people have died as a result of tsunamis. Although scientists know where and how they occur, predicting precisely when they will next take place is near-impossible. All they can do is provide as early a warning as possible to the affected nations.

Short of building very high walls around vulnerable coasts, there is little in the way of physical defenses against these powerful forces of nature. However, writing in the journal Heliyon, applied mathematician Usama Kadri of Cardiff University has come up with a rather clever way to literally turn the tide in our favor.


He is proposing using a series of devices that will blast the incoming tsunami with counteracting waves, which will help sap the tsunami’s momentum. This method would have been able to reduce the amplitude – and run-up height – of the cataclysmic 2004 Indian Ocean tsunami by about 30 percent.

Most tsunamis are generated when one major fault block slips vertically down under another and a large body of water is pushed horizontally forwards. The water moves like a slinky being pushed at one end, in that the surface does not move up and down as the wave makes its way towards the coast. This, in fact, is why the safest place to be during a tsunami is in the middle of the ocean.

When the water hits the coast, it slows down and the water piles up on itself. The more water that’s moved, and the more energetic the fault slip, the higher the crest will be.

By fine-tuning a series of artificial “acoustic-gravity waves” fired from devices along the coast, they could destructively interact with these types of tsunami waves and dissipate their energy somewhat. These devices are purely hypothetical at this point, but there’s no reason to think they could not be constructed.


The spread of the 2011 tsunami. PacificTWC via YouTube

“In practice, generating the appropriate acoustic–gravity [waves] introduces serious challenges due to the high energy required for an effective interaction,” Kadri writes. “However, if the findings are extended to realistic tsunami properties, we might be able to mitigate tsunamis and so save lives.” 

The 2011 Tohoku tsunami off the coast of Japan managed to reach a height of 39 meters (128 feet) on land – a terrifying record as it is, but even the lower-end heights of around 16 meters (about 53 feet) were devastating enough.

If anti-tsunami blasters were in place off the coast of Japan back in 2011, this tsunami could have theoretically been cut down to just 11 meters (36 feet) or so. This might have helped to save thousands of lives, and it would have dramatically reduced the amount of seawater that rushed over the seawall protecting the Daiichi Nuclear Power Plant in Fukushima.


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