The type of seismic wave that can only pass through Earth's mantle is the S-wave, also known as a secondary wave or shear wave.

Here's why:

* S-waves are transverse waves: This means they vibrate perpendicular to the direction they travel, similar to how a wave moves across a rope.

* Liquids and gases cannot support shear stress: S-waves require a solid medium to propagate.

* Earth's outer core is liquid: Therefore, S-waves cannot pass through the outer core.

In contrast, P-waves (primary waves or compressional waves) can pass through both solids and liquids because they travel by compressing and expanding the material.

So, while P-waves can travel through the entire Earth, S-waves are blocked by the liquid outer core and only pass through the solid mantle and crust.