You're only somewhat over two years late with that . . .
Put your hands flat on a table. Each hand is like a tectonic plate. The tabletop is like the earth's core. Move one hand toward the other and keep pushing. Usually one hand will push under the other and push that one up. That's how mountains are formed (that's what the pushed-up hand is: a mountain being formed). Push your hands straight together, without letting one be pushed up. Your fingers crumple up. That's also like mountains forming.
Put your hands side by side, and slide them past each other. They don't slide smoothly, but mementarily get hung up together, as knuckles pass knuckles and so on. Similarly tectonic plates don't have smooth, polished edges. They ruba gainst each other and get hung up on the unevenness. When they keep on moving, inevitably those hangups will eventually break loose and jerk. That's an earthquake.