Nakamura-HVSR (Horizontal Vertical Spectral Ratio)

The HVSR method (H/V Spectral Ratio or Nakamura) is a non-intrusive assay based on environment micro-vibrations recording (on ground surface according to the vertical and to N-S and E-W perpendicular directions). The horizontal and vertical components relation results in a composite signal which process and analysis lead to the Soil Fundamental Period. This parameter is critical to prevent that a man-made structure’s period matches the soil period resulting in seismic amplification for resonance with the consequent structural damage.