Empirical Earth · Shape, Curvature & the Horizon

The seismic shadow zone — X-raying a layered sphere of known radius

The claim

“Nobody has dug deep, so the molten core and 6,371 km radius are invented.”

What is true

You cannot see inside the Earth. Everything about its interior is inferred from measurements taken at the surface.

What is measured

Earthquake waves cast a P-wave “shadow zone” between 103° and 142° from the quake. That is the fingerprint of a layered, spherical Earth with a dense core.

What would show this is wrong

S-waves detected on the far side of Earth, or no P-wave shadow zone between about 103° and 142°.

Sources

  1. Seismic shadow zone & Earth's layered interior. S-waves vanish beyond ~103° from a quake (liquid outer core); P-waves are refracted into a shadow ring ~103°–142°. The Gutenberg discontinuity link
  2. Earth’s interior, read from seismic waves. Lehmann (1936) inferred a solid inner core from PKIKP arrivals inside the P-wave shadow zone; Dziewonski & Anderson’s Preliminary Reference Earth M link
  3. The seismic picture of the core. Browser-based tools such as the IRIS (EarthScope) Seismic Waves Viewer animate real earthquakes traveling through the planet, showing P-waves passing through link
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