Answer:
Seismic waves
Step-by-step explanation:
The seismic P and S waves are two waves that releases energy during propagation, resulting in the sudden shaking of the earth, which is commonly known as the earthquake.
The point from which the earthquake originates, is known as the focus and the location that is directly above the focus, on the ground surface is known as the epicenter.
The P waves and S waves are primary and secondary waves respectively. The P waves are characterized by the contraction and expansion in its direction of propagation. Whereas the S waves are shear waves.