Why the United States is becoming more vulnerable to natural disasters

The United States is becoming more vulnerable to natural hazards mostly because of changes in population and national wealth density—more people and more societal infrastructure have become concentrated in disaster‐prone areas. For most of the 20th century, the United States has been largely spared the expense of a catastrophic natural disaster. A great earthquake (magnitude 8 or larger) has not struck a major metropolitan area since the 1906 San Francisco earthquake. An extreme or catastrophic hurricane (Class 4 or 5) has not struck directly a major urban area since the one that hit Miami, Florida, in 1926. Yet even without such disasters, which might create losses well over 100 billion, the overall costs of natural hazards, such as extreme weather, drought, and wildfires, are estimated at 54 billion per year for the past 5 years, or approximately 1 billion per week National Science and Technology Council, 1997.