the labeling is correct,
S waves are transverse wave in which motion of particle is perpendicular to the direction of propagation,
Therefore, the shearing force, for the direction of propagation shown in the figure, will act in the same direction (up and down) and therefore particle displacement will be up and down.
What is shear displacement?
displacement along the surface on which shear force is acting are shear displacement.
Please explain me with the help of this picture.
But i think in this picture the labelling of shear displacement is not correct.
the labeling is correct,
S waves are transverse wave in which motion of particle is perpendicular to the direction of propagation,
Therefore, the shearing force, for the direction of propagation shown in the figure, will act in the same direction (up and down) and therefore particle displacement will be up and down.
Thank you..