  Materials engineered at the micro- and nano-meter scale have had a tremendous
and lasting impact in photonics and phononics, with applications ranging from
periodic structures disallowing light and sound propagation at stop band
frequencies, to subwavelength focussing and cloaking with metamaterials. Here,
we present the description of a seismic test held on a soil structured at the
meter scale using vibrocompaction probes. The most simplistic way to interact
with a seismic wave is to modify the global properties of the medium, acting on
the soil density and then on the wave velocity. The main concept is then to
reduce the amplification of seismic waves at the free surface, called site
effects in earthquake engineering. However, an alternative way to counteract
the seismic signal is by modifying the distribution of seismic energy thanks to
a metamaterial made of a grid of vertical, cylindrical and empty inclusions
bored in the initial soil, in agreement with numerical simulations using an
approximate plate model.
