Representative snapshots of the velocity field (the blue arrows) and energy density distribution (ϵ, filled contours) for (a) the S​_x motion and (b) the A_x one in a two-elliptic-tube configuration with the x-major orientation. The inset in each panel emphasizes the distribution of ϵ in a representative nonuniform layer, whose boundaries are shown by the solid red curves. The white contour indicates where the Alfvén frequency, ω_A = kv_A, equals the quasi-mode frequency deduced with the fitting procedure. Both computations pertain to a fixed combination, $[{\rho }_{\mathrm{i}}/{\rho }_{\mathrm{e}}=3,a/b=2.5,\overline{l}=0.4,d/b=5,kb=\pi /30]$. This snapshot is extracted from the animation available online. The ϵ contours in all snapshots are filled in such a way that darker portions correspond to larger ϵ. The blue arrows are also consistently scaled in all snapshots such that longer arrows correspond to stronger velocities.