=> How is it that we know so much about the Interior of the Earth?

* deepest wells ever drilled into the Earth only penetrate around 12 km (7.5 mi)

=> Seismic Waves (body waves = P & S) behave in predictable ways as they pass through earth materials => and we can follow
their path

Seismic Wave Behavior

- refraction and reflection

- velocity

- propagation

- shadow zones