How does an earthquake start?
What makes an earthquake happen? The rock of the earth\'s crust (地壳) may have a fault\', a kind of break in the surface. The blocks which make up the earth move, and sometimes this may cause the sides of the fault to move up and down or lengthways (纵向地) against each other. When one piece of rock starts to rub on another with great force, a lot of energy is used.