(a) Eigenfunctions for Rayleigh and Love wave fundamental modes at 20 s period computed using the effective transversely isotropic component of the 1-D model in western Alaska at (64|$^\circ$|N, 159|$^\circ$|W) (Data source 2). (b) Sensitivity kernels composing the integrals in eqs (42)–(45): |$A1 = W^2$|⁠, |$A2 = W^{\prime 2}/k^2$||$B1 = V^2$|⁠, |$B2 = (U - V^\prime /k)^2,$||$B3 = V U^\prime /k$|⁠, |$B4 = U^{\prime 2}/k^2$|⁠, |$E1 = WV$|⁠, |$E2 = (U-V^\prime /k) W^\prime /k$|⁠, |$E3 = W U^\prime /k$|⁠, |$X1 = V W^\prime /k$|⁠, |$X2 = W (U - V^\prime /k$|⁠), |$X3 = U^\prime W^\prime /k^2.$|⁠.