The type of seismic wave that travels the fastest through rock material by causing rocks to vibrate in the same direction as the waves is called a primary wave or P-wave.

Here's why:

* Fastest: P-waves travel faster than other seismic waves (S-waves and surface waves) because they are compressional waves. They cause particles in the rock to move back and forth in the same direction the wave travels.

* Compressional: This back-and-forth motion creates areas of compression (where the rock is squeezed) and rarefaction (where the rock is stretched).

Let me know if you'd like to know more about seismic waves!