Emergence of seismic metamaterials: Current state and future perspectives

Following the advent of electromagnetic metamaterials, researchers working in wave physics have translated concepts of engineered media to acoustics, elastodynamics and diffusion processes. In elastodynamics, seismic metamaterials have emerged in the last decade for soft soils structured at the meter scale, and have been tested with full-scale experiments on holey soils. Born in the soil, seismic metamaterials have emerged from the field of tuned-resonators buried in the soil, around building's foundations or near the soil-structure interface as local seismic isolators. Forests of trees have been interpreted as above-surface resonators, and coined natural seismic metamaterials. We first review some advances made in seismic metamaterials and dress an inventory of which material parameters can be achieved and which cannot, from the effective medium theory perspective. We envision future developments of large scale auxetic metamaterials for building's foundations, above surface resonators for seismic protection and metamaterial-like transformed urbanism at the city scale.