Seismic Layering, Gravity Anomalies, and the Magnetic Field — Probing Earth’s Interior | Interlude D from Earth: Portrait of a Planet
Seismic Layering, Gravity Anomalies, and the Magnetic Field — Probing Earth’s Interior | Interlude D from Earth: Portrait of a Planet How do geologists know what’s inside the Earth? In Interlude D of Earth: Portrait of a Planet , Stephen Marshak reveals the geophysical detective work that has unraveled our planet’s internal structure—using seismic waves, gravity measurements, and the mysteries of Earth’s magnetic field. To see a visual breakdown, watch the chapter video on YouTube , or keep reading for a comprehensive summary of how we peer into Earth’s hidden depths. Seismic Waves: Earth’s X-Rays Reflection & Refraction: Seismic (P- and S-) waves bend and bounce as they pass through materials with different properties, revealing Earth’s internal layers. Key Boundaries: The Moho marks the crust-mantle boundary. The low-velocity zone (LVZ) beneath the oceanic crust is linked to the ductile asthenosphere. Seismic shadow zones reveal the existence of the liquid oute...