The large and violent movements of the ground caused by an earthquake will generally disrupt many of the services we have come to rely upon for our comfort. Electric light poles are always vulnerable to damage and in most cases, after a serious tremblor, electric service will be severed. No electricity means no lights, heat (in most cases), and no water – assuming that the water mains are still intact. Those who use land-line phones will probably be without service, as may those with cell phones if the relay towers have been damaged or toppled. Natural gas pipelines could be broken, as well, presenting a danger of fire or explosion.Nearly all of our stores, including grocery stores, rely on food and other supplies being brought in by truck. When an earthquake has struck, and supply lines may be impacted, you will probably be startled at how quickly the shelves are stripped bare. A major quake can also damage local airports and train facilities, making it impossible for supplies to be brought in until repairs have been made. Bridges can also be destroyed or damaged to such an extent that they will be unusable. Other sections of the infrastructure can also be negatively impacted by an earthquake, such as power plants, especially nuclear power plants where the possibility of harmful radiation being released is present. Dams are another possible danger source, and if you live downstream of a dam while living in an earthquake zone, you might want to make sure that your plans for evacuation have been made. Facilities that process either sewage or hazardous industrial waste are other spots that might cause problems should an earthquake occur. Permanent ground deformations can tear a structure apart. Some foundation types are better able to resist these permanent ground deformations than others. For example, the use of pile foundations, with the piles extending beneath the anticipated zone of soil liquefaction, can be effective in mitigating the hazard’s effects. The use of heavily reinforced mats can also be effective in resisting moderate ground deformation due to fault rupture or lateral spreading. Most earthquake-induced building damage, however, is a result of ground shaking. When the ground shakes at a building site, the building’s foundations vibrate in a manner that’s similar to the surrounding ground. Brittle elements tend to break and lose strength. (Examples of brittle elements include unreinforced masonry walls that crack when overstressed in shear, and unconfined concrete elements that crush under compressive overloads.) Ductile elements are able to deform beyond their elastic strength limit and continue to carry load. For economic reasons, building codes permit buildings to be damaged by the infrequent severe earthquakes that may affect them, but prevent collapse and endangerment of life safety. For buildings that house important functions essential to post-earthquake recovery, including hospitals, fire stations, emergency communications centers, etc., codes adopt more conservative criteria that’s intended to minimize the risk that the buildings would be so severely damaged they could not be used for their intended function.