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.


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

Answer 1

A.

P-waves change speed when they pass from the solid mantle into the liquid outer core, causing them to refract (bend). That refraction redirects P-wave rays and produces the angular shadow zone on the opposite side of the Earth.