Rayleigh waves cause the ground to move in a retrograde elliptical motion. This means the ground moves in a circular path, but the direction of the movement is backwards compared to the wave's direction of travel.

Here's a breakdown:

* Horizontal motion: The ground moves back and forth in the direction the wave is traveling.

* Vertical motion: The ground also moves up and down, perpendicular to the wave's direction of travel.

* Combined motion: The horizontal and vertical motions combine to create a circular, or more accurately, elliptical path. The movement is "retrograde" because the direction of the ellipse's rotation is opposite to the wave's direction of travel.

Think of it like a rolling wave on the ocean. As the wave passes, a piece of seaweed on the surface will move in a circular path, but the direction of the circle's rotation will be opposite to the wave's direction of movement.

Rayleigh waves are also known as ground roll, and they are the slowest surface wave, but they can be very destructive due to their larger amplitude and long wavelength.