for National Geographic News
Places in the United States where people are most vulnerable to natural hazards have become more widespread over the past 40 years, a new map reveals.
The map reflects new research that uses a "social vulnerability index" to rate risk based on factors such as age, race, and socioeconomic status.
Scientists created the index to identify by county which populations may be less able to respond to and cope with natural disasters such as flooding, earthquakes, or hurricanes.
In the 1960s the greatest social vulnerability was centered in the Southwest, while in the 1970s one of the more dominant high-risk regions was the Texas-Mexico border.
Over the next few decades the concentrations of vulnerable people shifted so that there is now a more even distribution across the country.
"Social vulnerability is dynamic, changing over time and certainly across space," said lead study author Susan Cutter, a geography professor at the University of South Carolina.
"Our social vulnerability to natural hazards [overall] has been reduced a little bit, but there are areas where it has increased significantly."
Some of the current high-risk regions include Alaska, the Mississippi Delta, the Rio Grande border area, California's Central Valley, and large urban areas.
A paper describing the study appears today in the Proceedings of the National Academy of Sciences.
Today more U.S. citizens live in high-hazard areas—such as earthquake zones and coastal regions prone to hurricanes—than ever before.
But the new study focused exclusively on those people's vulnerability to the natural hazards they might face.
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