Model without layers and with the scattering parameters |$\sigma =15\%$| and a = 200 m; left-hand panel: L/R ratio as a function of the source–receiver distance. Note that the vertical scale is much smaller than in subsequent plots. The black line shows the mean over the 14 angular directions (see Fig. 2) and the yellow area shows one standard deviation; centre panel: dispersion curve for the rotations around the transverse axis Φ_T (perpendicular to the source–receiver direction). The black dotted line shows the theoretical Rayleigh wave fundamental mode; right-hand panel: dispersion curve for the rotation around the vertical axis Φ_V. The colour scale corresponds to rotation rate.