Science Olympiad Dynamic Planet Practice Test

What kind of wave is characterized by side-to-side motion in seismic activity?

1. P wave

2. S wave

3. Primary wave

4. Surface wave

The correct answer is: S wave

The correct choice is characterized by side-to-side motion, which is distinctly represented by S waves, or secondary waves. These waves move through the Earth following an earthquake and are known for their transverse motion, meaning they oscillate perpendicular to the direction of wave travel. When S waves travel, particles in the material they pass through move in an up-and-down or side-to-side motion, creating shear stress. This is opposed to P waves (primary waves), which are longitudinal waves that compress and expand the medium in the direction of their travel. Surface waves, while also a type of seismic wave, involve complex motion as they travel along the Earth's surface and can include both transverse and longitudinal components, but they do not strictly represent the side-to-side motion that defines S waves. Thus, the side-to-side motion in seismic activity is a definitive characteristic of S waves, clarifying why this choice is the best answer.