This helps identify where the greatest earthquake potential exists. Most faults mapped by geologists are inactive and have no earthquake potential. An earthquake is the shaking of the crust. A quake results when the crust moves suddenly along a fault. The sudden release of stored force in the crust causes waves of energy to radiate outward from the fault.
Internal waves form surface waves and the surface waves cause teh shaking of the ground.
Buildings in the path of waves may tilt and roll violently as the earthquake surface waves pass. The great movements of the crustal plates in western North America yield some of the most severe earthquakes. Central Idaho's high mountain ranges provide evidence of this crustal movement. Idaho is situated where the Basin and Range and Rocky Mountain provinces meet. Most of Idaho experiences the effects of tremendous crustal stretching.