What are S waves primarily characterized by?

S waves, or secondary waves, are primarily characterized by their ability to travel only through solid materials and not through liquids. This is a fundamental property of S waves, rooted in the mechanics of wave propagation. When an S wave encounters a liquid, it will not continue moving through it, causing a distinctive behavior during seismic events. This characteristic is crucial in understanding the Earth's internal structure, as scientists use S waves to infer the presence of liquid layers, such as the outer core, which does not produce S waves.

In contrast, options that suggest S waves can travel through both solids and liquids or are faster than P waves do not accurately reflect the behavior of these seismic waves. S waves are indeed slower than P waves, which are primary waves that can travel through both solids and liquids, allowing them to be detected in various types of geological formations. The shaking associated with S waves is often significant and can cause considerable damage during earthquakes, but the defining characteristic remains their restriction to solid mediums.