Can tsunamis be stopped in their tracks?

Posted 3 February 2017

Big waveTsunamis could be stopped before they hit the coastline, a Welsh mathematician has proposed in a study of deep-ocean sound waves.

Dr Usama Kadri, from Cardiff University's School of Mathematics, has suggested that firing deep-ocean sound waves at an oncoming tsunami could save lives and reduce on-shore damage. 

In the past, the risk posed by tsunamis sat fairly low on Australia’s list of natural disasters to worry about. However, that is starting to change here and abroad. 

“Tsunamis have been responsible for the loss of almost a half million lives, widespread long-lasting destruction, profound environmental effects and global financial crisis within the last two decades,” Kadri wrote in a recent journal paper

“The main tsunami properties that determine the size of impact at the shoreline are its wavelength and amplitude in the ocean.

“We show that it is in principle possible to reduce the amplitude of a tsunami, and redistribute its energy over a larger space, through forcing it to interact with resonating acoustic–gravity waves (AGWs).”

AGWs are a type of sound wave that can cut through the deep ocean at the speed of sound – much faster than tsunamis. They are naturally generated by underwater earthquakes, explosions, landslides, surface waves and meteorites. 

But Kadri has proposed engineering highly accurate transmitters – or modulators – to generate AGW frequencies mechanically.

“Once a tsunami is identified … we transmit two finely tuned trains of AGWs that upon interaction with the tsunami form a resonant triad,” Kadri wrote in open access journal Heliyon.

“Even if we consider extreme tsunami scenarios, in terms of proximity to shoreline as in the 2004 tsunami case, not many AGW-detection stations would be required to provide a worldwide alarm system that would serve all tsunami high-risk areas.”

However, Kadri acknowledged that designing AGW frequency transmitters presented a number of challenges. 

“In practice, generating the appropriate acoustic–gravity modes introduces serious challenges due to the high energy required for an effective interaction,” he wrote. 

“While detection is relatively straight forward, the mitigation of tsunamis requires the design of highly accurate AGW frequency transmitters or modulators, which is a rather challenging and ongoing engineering problem.”