Question

An earthquake generates a seismic wave that travels through several layers of the Earth's interior, shown below.



The lithosphere is made out of solid rock, the mantle is a combination of solids and liquids, and the outer core is a liquid.

The path of the seismic wave changes at the boundaries of each layer because
A.
each layer is made out of the same material.
B.
seismic waves always change direction after a few miles.
C.
each layer has different properties.
D.
the layers are different sizes.

Answer 1

C.

Seismic waves change direction at layer boundaries because each layer has different physical properties (composition, density, rigidity, and state: solid vs liquid), which change wave speed and cause refraction and reflection.