Earthquakes happen, scientists believe, through the shifting of continental plates. The surface of the Earth consists of a dozen or so major plates, like most of North America, or Africa plus nearby ocean bottoms. These plates float on the mantle like rafts of bubbles on diswhwater. As they collide and rub against one another, the edges stick and build up pressure and tension. Eventually the tension breaks whatever is holding the plates stuck, they jump a few inches or feet or more, which is the earthquake itself. Then they stick together again, and the pressure begins to build again.
yeah what they said. its 2 continental plates getting stuck against each other then jolting forwards or backwards. I just repeated that but in a more simple way. :)
An earthquake refers to the sudden vibrations of the earth's crust.
At the plate boundaries, the crust would experiene enormous stress and the rocks are forced to bend, thus energy would build up. When the rocks can no longer hold the stress, they snap and break along the fault lines. The huge amount of stored energy is released in seismic waves which cause the plates to vibrate violently, forming an earthquake.