Final answer:
Seismic waves are used by scientists to study Earth's interior by observing their reflection and refraction through the planet's layers, which reveals information about composition and state of these layers.
Step-by-step explanation:
Scientists use seismic waves to study the interior of Earth by closely monitoring how these waves travel through different materials within the planet. These waves behave similarly to sound waves, where variations in frequencies can indicate different compositions and structures. Seismic waves are categorized into primary (P-waves) and secondary (S-waves), each with distinctive properties; P-waves are compression waves that can travel through both liquids and solids, while S-waves are shear waves that cannot travel through liquids.
As seismic waves move through the Earth, they get reflected and refracted by the different layers, which provides valuable information regarding the density, composition, and state (solid or liquid) of these layers. Seismographs capture the seismic waves at the surface, and by analyzing the wave patterns, including the speed and direction of travel, scientists can construct a model of Earth's interior. This method has revealed that the Earth consists of several distinct layers, with the outer core being liquid and the inner core being solid. The study of seismic data is instrumental in understanding not only the physical structure but also the temperature and dynamic processes within the Earth's interior.