Combining surface waves and common methods for shallow geophysical survey
Geophysical data were acquired during a survey of the Hluboká Fault in the Czech Republic, Central Europe. The recorded surface waves are studied in the frequency range 8–200 Hz. Phase velocity dispersion curves of Rayleigh and Love waves are determined from pairs of three-component seismograms with a 5 m receiver spacing by means of a frequency-time analysis along the profile. Rayleigh waves are analysed on the vertical (Z) and radial (R) components and Love waves on the transversal (T) component. Dispersion curves from the vertical component are then inverted to 1-D S-wave velocity models using the isometric method. A set of 1-D S-wave velocity models representing a pseudo 2-D S-wave velocity distribution along the profile is obtained. This velocity distribution is compared with the results of other geophysical methods and also with direct observation from a shallow paleoseismic trenching. A combination of the S-wave velocities obtained from the surface wave analysis and P-wave velocities from refraction tomography is used to estimate the Poisson ratio distribution. It is shown that the resolution capabilities of surface waves are comparable in this case with electric resistivity tomography in near surface medium and with P-wave tomography in the depths exceeding approx. 15 metres.