An impending tsunami, an enormous surge powering its way across the ocean, is a fearsome prospect. Altogether, almost half a million people have been killed by tsunamis in the past two decades, including ones created by the 2011 ‘Great Tōhoku Earthquake’ off the coast of Japan in which more than 15,000 people lost their lives, and the 2004 Boxing Day Indian Ocean earthquake, which killed 230,000 people.
Embracing the science of ‘acoustic-gravity waves’ (AGWs) – very long sound waves, which are naturally created by trigger events such as earthquakes – Usama Kadri, from the Cardiff University School of Mathematics, has studied how using underwater hydrophones to detect and read these AGWs could help give vital warnings of, and potentially even prevent, approaching tsunamis. ‘You can use acoustic-gravity waves to say that there is an upcoming tsunami,’ explains Kadri.
“With the help of acoustic-gravity wave theory, you can now say where it started, the affected radius from the source, and the speed”
Kadri’s research suggests that, since AGWs can travel up to ten times faster than a tsunami itself, warnings urging people to head to higher ground could, in future, be generated much sooner. Additionally, with the right transmission technology, it might even one day be possible to fire AGWs back at the approaching tsunami in a way that would reduce its destructive potential. ‘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 them,’ says Kadri, ‘potentially saving lives, as well as preventing billions of pounds worth of damage.’
However, he stresses that, unlike using hydrophones for detection, the technology to transmit AGWs remains a major obstacle, not least because of the vast complexities created by applying this theory to the real world, but also because of the immense energy which would be required (the 2004 earthquake and subsequent tsunami generated more than 1,500 times the energy released by the Hiroshima atomic bomb).
This was published in the April 2017 edition of Geographical magazine.