1. The decay of nuclear substances in the Earth produces heat.
2. This heats the liquid mantle which forms a convection current.
3. These convection currents circulate beneath the crust.
4. These circulations cause massive forced to be built up as potential energy.
5. When this energy is released, it is usually as an earthquake.
Heat in the earths core causes convection currents in the mantle. These currents pull (can't think of a better word) on the tectonic plates and cause them to move across the surface of the earth.
Nearly all earthquakes occur at plate boundaries. The different plates are moving past each other in different directions and at different rates. If they slid past each other with no friction we would have no earthquakes. However they have a tendency to get stuck. This halts the movement building stress. The energy stored in the stress eventually overcomes friction and releases as seismic waves (earthquakes). The longer the build up of stress, generally, the larger the magnitude of the earthquake
Sorry this isn't explained very clearly but I'm tired. I'm sitting a mock on this tomorrow though so I need to know it
Posted from TSR Mobile