To guarantee high quality data, these holes must comply with the standards indicated in the relevant ASTM standards. In this type of seismic prospecting, the source and/or geophones are located in a specially prepared hole in the ground. The data acquired is are thus considered during the design, in order to build structures with different resonant frequencies with respect to the ground, thereby preventing the double resonance effect which is extremely dangerous for structural stability. Seismic microzonation studies using the HVSR measurement method have therefore become an integral, essential instrument in the design of earthquake-resistant buildings. The acquisition of HVSR data, obtained using low frequency triaxial geophones, makes it possible to determine with accuracy the characteristic frequency of resonance of the site, an essential parameter for the correct dimensioning of earthquake-resistant buildings. The latter, which provides the most reliable results, is also known as the HVSR (Horizontal to Vertical Spectral Ratio) method or the Nakamura method. The analysis of seismic noise measurements can be conducted using three methods: 1) Fourier spectra 2) Spectral ratios 3) H/V spectral ratios. In light of the new seismic legislation, the measurement of environmental seismic vibrations or seismic noise has acquired considerable importance. WHAT YOU NEED for SURFACE WAVES: active methods - MASW/Vs30 In summary, even the use of surface triaxial triads in combination with single-component geophones has allowed the development of so-called "unconventional" methods. On the other hand, making use of the dispersion of Love waves together with the Rayleigh waves using horizontal component geophones is an interesting development in MASW analysis, simplifying the interpretation of the most complex situations. MASW is traditionally performed by analysing Rayleigh waves, which are recorded using common vertical component geophones, the same that used also for seismic refraction waves and the Re.Mi. As, typically, the speed of the seismic waves increases with depth, the lowest frequencies of the surface waves will travel at a higher speed than the higher frequencies. velocity of shear waves and thickness of the layers) from the determination of the dispersion curves. Since the dispersion of the surface waves depends on the vertical variations of the subsoil, it is possible to obtain the characteristics of the medium (i.e. the fact that different frequencies with different wavelengths travel at different velocities).
This indicates that the phenomenon being analysed is the propagation of THE surface waves, or rather, the analysis focuses in detail on the dispersion of surface waves (i.e. MASW is the acronym for Multichannel Analysis of Surface Waves. MASW - MULTICHANNEL ANALYSIS OF SURFACE WAVES
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