Final answer:
Seismic waves are vibrations caused by earthquakes and include pressure waves (P-waves) and shear waves (S-waves). They help scientists study Earth's internal structure because they travel at different speeds through different materials.
Step-by-step explanation:
Waves created by earthquakes that travel through Earth's interior and along Earth's surface are called seismic waves. Seismic waves include different types, such as compressional or pressure waves (P-waves), and shear or transverse waves (S-waves), both of which travel at different speeds and have different properties.
P-waves can travel through liquids and solids whereas S-waves can only travel through solids, which provided crucial insights into the liquid nature of Earth's outer core. Additionally, there are surface waves that are analogous to waves on water, affecting Earth's surface during earthquakes. By studying the behavior of these seismic waves, scientists can infer the internal structure and composition of Earth.