Artificial Seismic Shadow Zone Created by Metamaterials
We developed a completely new method of earthquake-proof engineering to create an artificial seismic shadow zone using acoustic metamaterials. Helmholtz resonators intercept acoustic waves according to their resonance frequency, which creates a negative modulus or stop-band of the wave. By designing huge empty boxes with a few side-holes corresponding to the resonance frequencies of seismic waves and burying them around the buildings that we want to protect, the velocity of the seismic wave becomes imaginary. The meta-barrier composed of many meta-boxes attenuates the seismic waves, which reduces the amplitude of the wave exponentially by dissipating the seismic energy. This is a mechanical method of converting the seismic energy into sound and heat. We estimated the sound level generated from a seismic wave. The meta-barrier creates a seismic shadow zone, protecting all the buildings within the zone. This method of area protection differs from the point protection of conventional seismic design, including the traditional cloaking method. By adjusting the width and refractive index of the meta-barrier, the seismic range of the building can be upgraded and downgraded as needed without altering the building.