Elastic anisotropy due to aligned cracks has been the subject of many seismic physical modeling experiments. Different experimental approaches related to sizes, shapes and density of cracks has been taken into account in earlier investigations. In this paper we present a physical study of shear-wave splitting in anisotropy induced aligned cracked media. In this experiment, rubber discs were used as inclusions in a solid epoxy resin matrix. Pulse transmission measurements were carried out on a reference model (without inclusions) and two other models with different aperture of cracks and dissimilar crack densities. The seismic records were measured using three different S-wave source transducers with dominant frequency of 0.1 MHz (low frequency), 0.5 MHz (intermediate frequency) and 1 MHz (high frequency). Crack apertures to seismic wavelength ratio were varied from 1.3 to 13.3 in one model and 2.3 to 23.5 in the second cracked model. Our results show that effects associated with acoustic scattering, attenuation and velocity dispersion interfere directly in shear wave splitting, which in turn is a function of crack aperture and source frequency.

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A physical modeling study of the effect of overburden pressure on anisotropic parameters was conducted using intrinsically orthorhombic phenolic boards as the model. These boards were coupled together with the help of a pressure device and uniaxial stress was gradually increased while time arrival and velocity measurements were repeated. Results show maximum increase in compressional and shear wave velocities ranging from 4% to 10% in different directions as a function of increasing uniaxial stress. Anisotropic parameter gamma generally diminished with increasing pressure and ranged from 0% to 33%. We observed anisotropic behavior attributable to both orthorhombic and VTI symmetries. Polar anisotropy behavior is due primarily to layering or bedding and tends to increase with pressure. Certain anisotropic parameters however unveil inherent orthotropic symmetry of phenolic.Abstract cover is not included in abstract body.