Acquisition and inversion of shallow seismic surface waves (MIFO)
Shallow seismic surveys are used to investigate the shallow subsurface up to 20 m depth. The frequency content of the analysed signals is between 5 Hz and 100 Hz. The seismic waves are usually excited by a hammer blow on the surface. Therefore, the recorded seismograms are dominated by surface waves. Their high sensitivity to shear wave velocity and therefore shear modulus as well as the high signal to noise ratio (in comparison to body waves) make the analysis of surface waves attractive for shallow geotechnical investigations.
Surface waves are dispersive that means their propagation velocity depends on frequency. Analysing the dispersion provides information about the variability of material properties with increasing depth beyond the surface. Established methods used today (inversion of dispersion curves or wave field spectra) assume that there is no variability of material properties along the profile. This assumption is not satisfied in most applications of practical relevance. To overcome this limitation the full recorded seismograms have to be inverted. The development of an appropriate method is the aim of this project.