Earthquake that devastated Turkish resorts is explained
A powerful earthquake struck off the coast of Turkey last night, leaving two dead and hundreds more injured.Â
The magnitude-6.7 quake triggered a colossal tsunami, which swept through the country's Aegean coast and Greek holiday islands including Kos and Rhodes, leaving devastation in its path.Â
But how do they form and is there a way of stopping them?
Tsunamis such as this one are generated when larges swathes of the sea floor become disturbed by large and shallow earthquakes, caused by the turbulent movement of tectonic plates.
Scientists studying the behaviour of tsunamis hope that deep-ocean sound waves could one day prevent the killer waves from reaching the shore.
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Tsunamis are generated when larges swathes of the sea floor become disturbed by large and shallow earthquakes, caused by the turbulent movement of tectonic plates (pictured is a diagram explaining how a tsunami is caused)
Tsunamis usually occur at the boundary between two tectonic plates.
When tectonic plates brush against or collide with each other, one plate can 'subduct' below the other.
This causes pressure to build up which can suddenly result in a rupture of the ocean floor.Â
This rupture quickly displace large areas of the ocean floor and thousands of miles of ocean bed can be offset by a single quake.
This displacement causes a swell of long, high sea waves to rise above the surface.
As it reaches the surface, the tsunami is barely noticeable, appearing first as just a ripple.Â
But as the waves pace towards land, the water becomes shallower and the size of the tsunami increases.
A tsunami can move over water for hundreds of miles, devastating any land that it comes across.
Usually, it takes an earthquake with a Richter magnitude exceeding 7.5 to produce a destructive tsunami, which explains why most tsunamis occur in the Pacific along its Ring of Fire, where large tectonic movements happen more frequently.
In January, researchers suggested that deep-ocean sound waves could be used to stop tsunamis before they reach land.
The mathematician has proposed a radical new method to dissipate tsunami energy by firing acoustic-gravity waves, reducing its height to minimise damage to both human life and the environment.
Map of The Ring of Fire is a major area in the basin of the Pacific Ocean where a large number of earthquakes and tsunamis occur
Ultimately, the researcher says these waves could be fired repeatedly at an incoming tsunami to wipe it out entirely by spreading its energy over a large area.
The potentially life-saving technique, proposed by Dr Usama Kadri of Cardiff University’s School of Mathematics, was described in a paper published to the journal Heliyon.
According to the mathematician, naturally occurring acoustic-gravity waves (AGWs) could react with a tsunami in a way that forces its energy to spread out.
AGWs can travel thousands of meters below the surface, moving at the speed of sound.
Damaged boats are seen after an earthquake and a tsunami in the resort town of Gumbet in Mugla province, Turkey
Fallen bricks are seen on the Greek island of Kos after a 6.4-magnitude quake triggered tsunami waves to devastate surrounding land
If we can find a way to engineer AGWs, they could be fired at tsunamis to reduce the amplitude, or height, of the monstrous wave, the researcher said.
‘Within the last two decades, tsunamis have been responsible for the loss of almost half a million lives, widespread long-lasting destruction, profound environmental effects and global financial crisis,’ Dr Kadri said.
‘Up until now, little attention has been paid to trying to mitigate tsunamis and the potential of acoustic-gravity waves remains largely unexplored.’
The image illustrates the evolution amplitudes (wave height). As the tsunami moves from right to left, it comes in contact with the acousticâ€"gravity waves, that are moving left to right. This forces the tsunami's energy to spread out, reducing its amplitude
The illustration (a) shows the tsunami and acoustic-gravity waves generated in the 2004 Indian Ocean earthquake, revealing how AGWs travel much faster to the proposed detection station. An Illustration of the proposed mitigation system is shown as well (b)
For the plan to work, the researcher said it will first be necessary to develop highly accurate AGW frequency transmitters or modulators, though this will be challenging.
And, it may also be possible to harness the naturally occurring AGWs that are generated in the geological event itself.
The researcher has already shown that a deep ocean system of this kind could be used for early detection.
‘In practice, generating the appropriate acoustic-gravity waves introduces serious challenges due to the high energy required for an effective interaction with a tsunami, ’ Dr Kadri said.
‘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.’ Â
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