Lateral Waves in a One-Dimensionally Anisotropic Half-Space
Anisotropy in conductivity is found in various stratified media including alternating layers of dense rock with low conductivity and less dense rock with higher conductivity shown schematically in Fig. 9.1.1. In such media, the conductivity transverse to the bedding surfaces is always smaller than that along these surfaces (Parkhomenko 1967). For horizontal surfaces, this means that σ2z is smaller than σ2x = σ2y, e.g., σ2z ~ 0.002 S/m and σ2x = σ2y ~ 0.004 S/m. Anisotropy in conductivity is also found in only slightly stratified hard clay (for which the conductivity ratio of 2 is appropriate) and in rocks with different conductivities along the principal crystallographic axes. It may be added that a slightly inclined stratification must also exhibit different conductivities to the components of current parallel to the bedding surfaces and those perpendicular to them. In this case, σ2x and σ2y may differ somewhat from each other and more substantially from σ2z.
KeywordsClay Anisotropy Attenuation Stratification Bedding
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