Question

What happens to the P and S waves at the Gutenberg Discontinuity?

Answer 1

At the Gutenberg Discontinuity, which marks the boundary between the mantle and the core, P-waves (Primary waves) slow down significantly, while S-waves (Secondary waves) disappear completely.

• P-waves can travel through both solids and liquids, but they slow down as they pass through the outer core, which is in a molten (liquid) state.
• S-waves, which can only travel through solids, cannot pass through the liquid outer core, causing them to disappear entirely at this boundary.

This behavior provides evidence that the outer core is liquid.