Final answer:
Seismic waves travel faster in solids due to the medium's rigidity, with P-waves being faster than S-waves, which cannot travel through liquids like Earth's liquid core. The speed difference is critical for understanding Earth's structure and pinpointing earthquake epicenters.
Step-by-step explanation:
Seismic waves travel faster in solids than in liquids; however, unlike P-waves, S-waves cannot travel through liquids.
The speeds at which seismic waves travel are significantly affected by the rigidity of the medium. For instance, P-waves, or pressure waves, in granite travel faster (4 to 7 km/s) because the bulk modulus of granite is greater than its shear modulus. On the other hand, S-waves, or shear waves, travel slower (2 to 5 km/s) in granite and cannot be supported by liquids, such as Earth's liquid core. This difference in wave speed and behavior through various mediums provides valuable data in geophysics, allowing scientists to understand Earth's interior structure and accurately locate earthquake epicenters.