The seismic waves that travel only across the surface of the Earth are called surface waves.

There are two main types of surface waves:

* Love waves: These waves are horizontally polarized, meaning they shake the ground from side to side. They travel faster than Rayleigh waves.

* Rayleigh waves: These waves are a combination of both longitudinal and transverse motion, causing a rolling or elliptical motion of the ground. They are slower than Love waves.

Surface waves are responsible for much of the damage caused by earthquakes, as they can travel long distances and have a large amplitude.