A broadband zero-frequency seismic metamaterial based on negative effective mass density

This study introduces the application of negative effective mass theory to design seismic metamaterials (SMs) featuring zero-frequency band gaps, targeting ultra-low frequency seismic surface waves (0-5 Hz). Investigating buried cylindrical SM unveils a zero-frequency band gap and its effective mass-spring model indicates a negative effective mass below the cutoff frequency. Based on the theoretical model, the optimized square cavity SMs achieve an impressive 267% wider zero-frequency band gap (0-4.29 Hz). For practical engineering, the equivalent attenuation effects of bedrock and fixed boundary conditions on the seismic surface waves are analyzed at ultra-low frequencies.