They could diminish the surface waves' destructive power

Jul 21, 2009 07:36 GMT  ·  By
Surface waves are responsible for most damage that is inflicted on buildings during an earthquake
   Surface waves are responsible for most damage that is inflicted on buildings during an earthquake

Earthquakes are among the most brutal manifestations of nature, alongside volcano eruptions and tsunamis, and, as if that wasn't enough, oftentimes the three come together. Tremors strike in two ways – via body waves, which travel underground away from the initial point, and surface waves. The latter travel at ground level and are widely held responsible for the largest amount of damage that is caused when an earthquake hits. Scientists from the University of Liverpool now believe that using invisibility cloaks may help building owners experience catastrophic damage, by redirecting the force of a tremor's surface waves, AlphaGalileo reports.

According to the researchers, installing concentric plastic rings in the foundations of new buildings could be enough to redirect a sufficient amount of a tremor's force. They argue that the stiffness and elasticity of the plastic would be the factor that would have the most influence on how the shock waves are handled. Because of their circular structures, the rings would essentially mask the building behind them, hence the name “invisibility cloak.” The power of the surface waves would lose its destructive force, which would be converted into variations in the density and pressure of the plastics.

“The waves are then directed outside the cloak where they return to their previous size. The cloak does not reflect waves – they continue to travel behind it with the same intensity. At this stage, therefore, we can only transfer the risk from one area to another, rather than eliminate it completely,” University of Liverpool Department of Mathematics Professor Sebastien Guenneau explains about the new system. He has been one of the main developers of the new protective method, alongside Fresnel Institute (CNRS) experts Stefan Enoch and Mohamed Farhat. CNRS is based in Marseilles, France.

“This work has enormous potential in offering protection for densely populated areas of the world at risk from earthquakes. The challenge now is to turn our theories into real applications that can save lives – small scale experiments are underway,” the scientist adds. The team is, at this point, looking for appropriate materials to build their cloak from. The materials need to meet exact elasticity and density standards, so as to ensure that they do not rupture when intensive force is applied to them. Details appear in the latest issues of the journals Applied Physics Letters and Physical Review Letters.