The diagram above illustrates the point that hazard events (such as earthquakes, hurricanes, floods, fires, etc.) do not occur in a vacuum. Events occurring in areas with dense population will result in greater harm (by absolute numbers) than events in l ess dense areas. Similarly, hazards occurring in areas made vulnerable by poor economic development will result in greater harm than those occurring in stable areas. Vulnerable areas include river water sheds, undefended coastal plains, and hillsides pr one to landslides (perhaps from deforestation). Many lesser developed countries have large populations living on vulnerable ground.

In the concentric circles above, areas of greater population density are represented in the outer circle. Similarly, areas of greatest vulnerability are depicted in the outermost circle.