How do you know that the tectonic plates move?

Tectonic plates move as the result of enormous pressures placed on them by the forces of the Earth. They float on the molten rock that is deep underground. Where the plates come together is a fault line, and pressure may build up here as plates try to move in different directions but are unable to because they hold each other back. When there is enough pressure the plates will move suddenly, slipping against each other and causing an earthquake.