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Imagine a slinky being stretched and compressed; this is similar to how Primary waves, or P waves, travel. They are the fastest type of seismic waves and one of the first indicators that an earthquake has occurred.

P waves can move through all types of materials—solids, liquids, and gases—because their motion involves the compression and extension of matter. The particles of the medium through which P waves travel move in a parallel direction to the wave energy itself. For instance, if a P wave is moving to the right, the particles are also pushing and pulling in the same rightward direction.

This feature allows P waves to be extremely fast, racing through the Earth's crust and mantle, and even penetrating its liquid outer core.

Imagine cracking a whip or the ripples from throwing a stone into water; this is akin to how Secondary waves, or S waves, move through the Earth. They are slower than P waves and surface waves because their movement is more complex.

S waves are characterized by their movement that shakes the ground perpendicularly to the direction they are traveling. If an S wave is traveling toward the east, it will move particles up and down or side-to-side in a north-south direction. This shearing motion can only occur within solid materials, making S waves unable to travel through liquids or gases, such as Earth’s outer core or the atmosphere.

During an earthquake, these waves trail behind P waves and can cause significant damage due to their shaking motion.

Imagine sliding a rug across a floor; this back-and-forth motion resembles the horizontal movement produced by Love waves, or L waves. Among surface waves, L waves travel quickly, but they are slower than the body waves P and S.

Love waves are trapped close to the Earth’s surface, gliding horizontally through the uppermost layers of the crust. They cause the ground to sway side-to-side, perpendicular to the direction of the wave. Efficient energy transmission makes Love waves particularly damaging to the foundations of structures. Because they require a rigid medium, you will not find Love waves moving through water or air but only through the solid crust of the Earth.

For a visualization of Rayleigh waves, or R waves, picture ocean waves rolling onto a beach. Rayleigh waves move in a rolling motion that involves both an up-and-down and a side-to-side movement as the wave energy travels forward.

These waves can travel through any type of material—solid, liquid, or gas—but they tend to be more intense at the surface and weaken with depth. This characteristic motion of Rayleigh waves can be especially destructive to buildings during an earthquake, as it results in the ground moving in elliptical patterns similar to the way particles move in water waves. R waves commonly follow L waves and are usually responsible for the rolling sensation felt during an earthquake.