(January 2011) Increasing disaster threats not only reflect the onset of events such as earthquakes or floods, but also the changing demographic and socioeconomic characteristics of the population. A large, violent tornado, for instance, passing through an open field presents little danger. On the other hand, a relatively weak tornado can pose significant risks to human life and can result in great economic losses in densely populated areas. While the intensity is important, of equal or greater importance is the presence of a population whose demographic or socioeconomic characteristics may place its members at greater risk of harm before, during, and after a day
The "vulnerability" perspective in disasters, which is rapidly emerging as a dominant view in the field, assumes that a real disaster occurs when it strikes an underprivileged population. Vulnerability is formally defined as "the characteristics of a person or group and their situation that influences their capacity to anticipate, cope with, resist, and recover from the impact of a natural hazard."1 Implicit here is "differential vulnerability"; that is, different populations face different levels of risk and vulnerability. Consequently, policies aimed at addressing risk and vulnerability must also take into account these differential impacts and outcomes of disasters. Although the sources of vulnerability are multiple and quite diverse, some of the most important factors that affect vulnerability include population growth and distribution and social diversity.
Population Growth and Distribution
Population growth and distribution, especially increased population density and urbanization, increases vulnerability to disasters.2 Nearly 80 percent of the U.S. population resides in urban areas, resulting in increasing population concentration in coastal communities and flood-prone areas. Congestion, limited escape routes, dense infrastructure, and poverty add to the vulnerability. Cities and countries in other regions of the world face similar problems. For example, researchers argue that in countries such as China, urban earthquakes are more dangerous because of the density of the infrastructure.3 The growth of coastal populations, for instance, raises important concerns about increased human exposure to coastal flooding, hurricanes, and tsunamis.4 The organization of work and leisure around coastal areas in India was one of the factors that resulted in high rates of injuries and fatalities following the 2004 Indian Ocean tsunami.5
social diversity