Where is the energy stored before an earthquake?
Before an earthquake, the tectonic forces that drive the plates cause the rock in the vicinity of a fault to distort and bend. Energy is stored in the rock as it deforms, in much the same way as energy is stored in a rubber band as it is stretched. This energy is called elastic energy. When the forces exceed the strength of the rock along the fault, the fault suddenly slips, just as the stretched rubber band snaps back to its original shape when it is let go. The point on the fault at which slip first occurs is the focus (or hypocenter) of the earthquake. The point on the surface of the Earth directly above the focus is the epicenter of the earthquake. The area of slip on the fault grows rapidly outward from the focus and may extend upward to the surface of the Earth.
so if the fault is fairly smooth and straight not much energy would have to be stored before each earthquake. a strong, rough, crooked fault would store a lot of energy. anything that acts as a lubricant would lower the energy stored. Near Denver, Colo. they stored poison gas underground and people were worried that it would cause an earthquake and the gas would escape.