Elastic waves as a Foucault pendulum?

The rotation of the Earth leads to a change in the equation of motion because of the Coriolis force. We study how Earth’s rotation affects elastic wave propagation. We show that the Coriolis force does not deflect seismic rays because the medium that carries the waves moves with Earth’s rotation. However, Earth’s rotation causes a weak traverse component of P-waves and a weak longitudinal component for S-waves. More importantly, S-waves with opposite circular polarizations propagate with different velocities. These two circularly polarized S-waves can be superposed to form a lineally polarized shear wave whose polarization slowly rotates in exactly the same way as Foucault’s pendulum. When Earth is rotated over 2π the polarization of the shear waves does not return to its original value, unless the wave propagates along the rotation axis. This is a seismic manifestation of the Berry phase.