Which seismic wave moves side to side and can only travel through solids?

• A. P-waves
• B. S-waves
• C. Surface Waves
• D. Love Waves

Answer: (B)

Seismic waves differ in how they move rock and what they can travel through. The wave that shears rock side to side, moving perpendicular to the direction it travels, is a shear (transverse) wave. Because liquids can’t support shear stress, this type of wave can only propagate through solids. In contrast, compressional waves push and pull along the direction of travel and can move through solids, liquids, and gases. Surface waves travel along the Earth’s surface and include motions like horizontal shearing in some cases. So the description—side-to-side motion and travel only through solids—matches the shear waves.