(4)Changes in social conditions and earthquake damage

The nature of earthquake damage changes as conditions in society change, particularly with respect to urbanization and the development of large housing areas. For example, the 1936 earthquake (M 7.5) and 1978 earthquake (M 7.4 Miyagi-ken-Oki Earthquake) that occurred in the Pacific Ocean off the coast of Miyagi Prefecture had nearly identical hypocenters and were of nearly the same magnitude. The extent and nature of the damage, however, were quite different. The damage in Miyagi Prefecture by the 1936 earthquake resulted in the injury of 4 people, the complete collapse of 3 houses, the partial collapse of 2 houses, and the fissuring of roads. The damage in Miyagi Prefecture by the 1978 earthquake was more severe, however. A total of 28 people died, 1,325 people were injured, and 1,183 houses were completely destroyed. The damage was particularly severe in those areas with new housing. The basic infrastructure urban area that are indispensable for daily life, including gas, water, and electrical supply, were also damaged, essentially bringing daily life to a halt in Sendai City (For details refer to 4-2 (3)). It has been surmised that the degree of urbanization and the development of large housing areas were key differences in the extent of the damage sustained.