Final answer:
The speed, direction, and intensity of seismic waves can change as they travel through different materials within Earth's interior, with speed depending on material rigidity.
Step-by-step explanation:
As seismic waves travel through Earth's different layers, the speed, direction, and intensity of the wave can change. The speed of seismic waves depends upon the density and rigidity of the materials they pass through. For instance, the velocity is higher in more rigid substances like granite, with P-waves traveling between 4 to 7 km/s and S-waves traveling between 2 to 5 km/s. In less rigid materials such as sediments, these waves travel slower. P-waves, being longitudinal, can travel through both solid and liquid mediums, whereas S-waves, which are transverse, cannot travel through liquids, leading to the creation of shadow zones. This behavior helps scientists to construct models of Earth's interior, revealing its layered structure consisting of a solid inner core surrounded by a liquid outer core.