Which surface waves travel in a horizontal shear direction and can only move through solids?

Love Waves are a type of surface seismic wave that move in a horizontal shear direction, which is a characteristic that sets them apart from other types of seismic waves. They propagate through the ground by causing particle motion that is lateral and perpendicular to the direction of wave travel, which results in a side-to-side motion.

This unique movement is significant because Love Waves cannot travel through fluids or gases; they require a solid medium to propagate. This is due to their reliance on shear wave motion, which cannot occur in materials that do not have a definite shape, such as liquids.

In contrast, Rayleigh Waves involve both longitudinal and vertical motion and can travel through both solids and liquids. P Waves, or primary waves, are compressional waves that can move through gases, liquids, and solids. S Waves, or secondary waves, do indeed move through solids but are generally not categorized as surface waves like Love Waves. Therefore, the defining characteristics of Love Waves as horizontal shear waves specifically confined to solids make them the correct answer to the question.