The observation that earthquakes and volcanoes mostly occur along particular boundaries along with other lines of evidence gave rise to and fully support the theory of tectonic plates and continental drift. The following video presentations describe this in more detail. Both videos provide animations of how the plates move with respect to one another. The second gives a longer but more detailed description
1. https://www.youtube.com/watch?v=nCIR0pZuqck
2. https://www.youtube.com/watch?v=HrKTuCDierM