Scientists have observed that certain phenomena seem to occur before an earthquake as the pressure within the plates intensifies. Myriads of tiny cracks appear in the rock, causing it to expand and uplift the ground above it. The pressure squeezes water out of the rock, thereby raising nearby water levels. Also the rock becomes more resistant to electric current, and radon gas is released. Scientists hope that these interrelated phenomena will provide keys to predict when and where an earthquake will occur, thereby enabling them to warn people to evacuate the area. While the earthquake itself cannot be prevented, at least lives may be saved. Particularly if they occur in sparsely _____ areas.