Phys. Rev. Lett. 112, 133901 (2014)

Cloaking, the ability to render an object invisible to electromagnetic and acoustic waves, has been the subject of intense research thanks to recent developments in the field of metamaterials. A cloaking metamaterial acts as an invisibility shield, which cancels any presence of the propagating wave within the shielded region. This is a powerful idea that has potential applications beyond electromagnetic and acoustic cloaking. Stéphane Brûlé and co-workers have now proposed a proof of concept by applying this idea to realize a seismic cloak. In their experiment, the authors built a seismic metamaterial constituted of a 'mesh' of vertical cylindrical voids dug out of silty clay soil and analysed its masking behaviour by shocking it with 50-Hz seismic waves. Their results show how the metamaterial is capable of strongly attenuating the energy of the seismic wave, as close as 10 m from the wave epicentre.