Plate tectonics is the theory (nothing in science can be absolutely proven) that the Earth is constantly moving, usually only a few inches per century. If it moves more than this, there is an earthquake. Plate tectonics mainly deals with the crust of the earth, not the mantle or core. The theory of Pangaea is relative to this. The Pangaea theory says that the continents as they are now have moved apart over millions of years to make the world the way it is today, although to be fair to them, some creation scientists/geologists say that Pangaea was pulled apart rather suddenly in geological terms (only 40-150 days!). Plate tectonics is the reason earthquakes in, say, Wisconsin are not as felt or as damaging as an earthquake in, say, California-because Wisconsin is at the center of a plate, and California is at the convulsion of two plates. Plate tectonics is the reason earthquakes happen-when the plates move too fast, an earthquake happens.