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.

Question

Which of the following statements best explains the P-wave shadow zone?
A.
Unlike S-waves, P-waves are not capable of moving in a curved path, and thus travel through the liquid outer core.
B.
P-waves are attracted to the electrical currents in the liquid outer core, and thus are pulled towards the core and away from the mantle.
C.
P-waves carry more energy than S-waves, thus enabling them to travel through Earth in nearly straight paths.
D.
As P-waves move from the mantle into the liquid outer core, they refract due to the change in density.

Answer 1

The best explanation for the P-wave shadow zone is:

D. As P-waves move from the mantle into the liquid outer core, they refract due to the change in density.

This statement accurately describes the behavior of P-waves when they encounter different materials within the Earth. P-waves (primary waves) can travel through both solid and liquid, but their speed changes when they move from a solid medium (the mantle) to a liquid medium (the outer core), causing them to bend or refract. This bending results in a shadow zone where P-waves are not detected.