Love Seam‐waves in a Horizontally Inhomogeneous Three‐layered Medium*

Using the WKBJ‐method the absorption‐dispersion relation and the amplitude functions are derived for Love seam‐waves that propagate in a horizontally inhomogeneous three‐layered medium. To describe the anelastic friction the constant Q‐model is applied. The inhomogeneity that appears in either the elastic moduli or quality factors is assumed to remain weak in the coal as well as in the adjacent layers, which are assumed to have different material properties (asymmetric channel). Using numerical solutions of the dispersion relation, it is shown that the weak horizontal inhomogeneities can be optimally detected using channel‐wave constituents of a frequency near to the Airy frequency while inhomogeneities of the adjacent rock can only be detected at frequencies close to, but higher than, the cut‐off frequency.