How do sesmic waves suggest the layering of the earth interior?

Seismic waves, generated by earthquakes or artificial sources, travel through the Earth and behave differently depending on the materials they encounter. By analyzing the speed and path of these waves, scientists can infer the composition and state of Earth's interior layers. For instance, seismic waves travel faster through solid materials than through liquids, indicating the presence of a solid inner core and a liquid outer core. Additionally, the reflection and refraction of seismic waves at boundaries between different layers reveal the distinct layers of the Earth's crust, mantle, and core.