Of all the natural disasters, none has a greater potential to cause widespread casualties and destruction of property than a large earthquake centered in an urban area. This scenario was tragically illustrated in 1976 when two large earthquakes occurred in heavily populated areas. In February, an earthquake measuring 7.6 on the Richter Scale struck Guatemala and left 30,000 dead and 100,000 people injured. In July ofthat same year, a Richter 7.8 earthquake devastated the city of Tangshan, China. The earthquake destroyed over 90% of the buildings in that city and caused the deaths of over 240,000 people. Since earthquakes strike without warning, preparation and disaster planning are mandatory in order to reduce injury and mortality.