Seismic waves, specifically Primary (P) waves and Secondary (S) waves, are vibrations generated by earthquakes or artificial explosions. These waves travel through Earth and provide crucial insights into the planet’s internal structure, much like how medical imaging reveals the inside of the human body.
Types of Seismic Waves:
- P-waves (Primary waves) are compressional waves that travel fastest and can move through both solids and liquids.
- S-waves (Secondary waves) are shear waves that travel slower and can move only through solids, not liquids.
Revealing Earth’s Interior:
- By observing how these waves travel, reflect, and refract through different layers, scientists can infer properties like density, composition, and phase (solid or liquid) of Earth’s interior.
- For example, the absence of S-waves in the outer core provides strong evidence that it is liquid, while P-waves bending at boundaries reveals transitions between layers like the crust, mantle, and core.
Seismic wave analysis has been vital in building a layered model of Earth, revealing a solid inner core, liquid outer core, viscous mantle, and brittle crust—all without physically accessing these depths.