4. Free oscillation modes
Spheroidal mode (analogous to the P, SV and Rayleigh waves). Motions are parallel to the radial direction. Sensitive to gravity, or density. nSl
Toroidal mode (analogous to SH or Love waves). nTl

7. Spheroidal mode (example)

10. Spheroidal mode (example)

11. Toroidal mode (example)

27. Phase velocity and Group velocity
Phase Velocity: Velocity of a wave peak or trough of a harmonic component.
Group Velocity: Velocity of the energy packet

29. Phase velocity Medium parameters
(scale lengths of layering, intrinsic P and/or S velocities, rigidity, etc.).
Geometric “fit” of a particular harmonic component into the associated boundary conditions.

30. Group velocity
Medium parameters through their influence on the phase velocity.
Variation of phase velocity with frequency, which controls the interference between different harmonics.

34. Time
Wavepackets
Phases