We have previously learned that the leading edge of a ripple on water is roughly concentric because water is essentially consistent or made up of the same material.
We also noted that the edges of the earthquake waves are not concentric. This is because the material that makes up Earth is not consistent. In fact, the type of material the seismic waves are traveling through influences how fast or slow the waves can travel. Thus changes in the material causes the waves to speed up in some places and slow down in others.
Watch the clip to see one way seimic waves help us infer what is inside Earth.
