Question

The diagram below is a cross-section through the Earth. The black and white rays represent the paths of P-waves and S-waves respectively as they travel through the Earth from an earthquake epicenter. Examine the diagram, then answer the question that follows.


The paths shown for S-waves represent direct paths. What can scientists infer from examining these direct paths of S waves and the S-wave shadow zone?
A.
Earth has a liquid layer.
B.
Earth has a solid core.
C.
Earth has a fractured crust.
D.
Earth has a thin crust.

Answer 1

A. Earth has a liquid layer.

S-waves cannot travel through liquids. The observed S-wave shadow zone (areas with no direct S arrivals) shows S-waves are blocked by a liquid outer core, so part of Earth's interior must be liquid.