On the Absorption‐dispersion Characteristics of Channel Waves Propagating in Coal Seams of Varying Thickness1

The WKB‐method is used for the derivation of both the complex dispersion relation and displacement functions for Love channel‐waves that propagate in a coal seam of varying thickness. The constant Q‐model is used to describe the anelastic friction. With numerical solutions of the absorption‐dispersion relation, the influence of thickness changes on the phase velocity and absorption coefficient of Love seam‐waves is analysed at various frequencies. It is shown that the changes in the seam thickness can be optimally detected around the average Airy‐phase frequency. An equivalence is pointed out between the wave guide structures: homogeneous with varying seam thickness and horizontally inhomogeneous with constant seam thickness.