Earthquakes and Seismology in Earth’s Interior

While physical evidence like xenoliths and meteorites provide clues, geologists primarily use seismic waves to map the physical properties and layers of Earth's interior.

Seismic waves are produced by earthquakes which result from stress rupture along faults. Surface waves travel along the crust, while body waves (P-waves and S-waves) travel through the interior to provide data on density and composition.

By tracking how P-waves and S-waves travel, reflect, and refract through the planet, scientists identified the liquid nature of the outer core due to the S-wave shadow zone and the density shifts at the core-mantle boundary.

Detailed seismic analysis reveals the Moho boundary, the low-velocity zone separating the lithosphere and asthenosphere, the transition zone, and the complexities of the D'' layer, leading down to the solid inner core.