APPLICATION OF SEISMIC RADIAL ANISOTROPY FOR NEAR-SURFACE FRACTURES IDENTIFICATION

Fractures significantly control the groundwater flow and solute transport in geological settings of low-permeable rocks. Fractures also affect seismic wave propagation. For instance, they can create a directional dependence of seismic velocity with respect to their orientations, known as seismic anisotropy. Seismic radial anisotropy as used here is the difference between the velocity of a vertically polarized S-wave (SV) and one polarized horizontally (SH). In this thesis, seismic radial anisotropy was used to evaluate its usefulness for correlating with near-surface fractures. The seismic radial anisotropy models were obtained at two sites from dispersion analyses of the Rayleigh waves, with vertical polarization, and Love waves, with horizontal polarization, using the Multichannel Analysis of Surface Waves (MASW) method. The seismic radial anisotropies at these two sites in different geological settings (one metamorphic-igneous bedrock and the other sedimentary), shows a strong correlation of seismic radial anisotropy with near surface fractures, and hence, can be used to characterize near-surface fractures.