We just learned about the Tectonic Plates.
Another part of earthquake science is a fault.
When the tectonic plates smash into each other, the place where the earth's crust touches from two different plates is called a fault.
When the plates move, not every part of the crust will run into other parts.
There are a bunch of different types of faults, depending on how the two pieces of crust run into each other.
(from: wikipedia - earthquake)
Kid Facts - Blast from the past: Chisel