Temporal and spatial changes in social vulnerability to natural hazards

doi:10.1073/pnas.0710375105

Temporal and spatial changes in social vulnerability to natural hazards

Susan L. Cutter* and
Christina Finch

Hazards and Vulnerability Research Institute, Department of Geography, University of South Carolina, Columbia, SC 29208

Edited by B. L. Turner II, Clark University, Worcester, MA, and approved December 21, 2007 (received for review November 2, 2007)

Abstract

During the past four decades (1960–2000), the United States experienced major transformations in population size, development patterns, economic conditions, and social characteristics. These social, economic, and built-environment changes altered the American hazardscape in profound ways, with more people living in high-hazard areas than ever before. To improve emergency management, it is important to recognize the variability in the vulnerable populations exposed to hazards and to develop place-based emergency plans accordingly. The concept of social vulnerability identifies sensitive populations that may be less likely to respond to, cope with, and recover from a natural disaster. Social vulnerability is complex and dynamic, changing over space and through time. This paper presents empirical evidence on the spatial and temporal patterns in social vulnerability in the United States from 1960 to the present. Using counties as our study unit, we found that those components that consistently increased social vulnerability for all time periods were density (urban), race/ethnicity, and socioeconomic status. The spatial patterning of social vulnerability, although initially concentrated in certain geographic regions, has become more dispersed over time. The national trend shows a steady reduction in social vulnerability, but there is considerable regional variability, with many counties increasing in social vulnerability during the past five decades.

Footnotes

*To whom correspondence should be addressed. E-mail: scutter{at}sc.edu
Author contributions: S.L.C. designed research; S.L.C. performed research; S.L.C. and C.F. analyzed data; and S.L.C. and C.F. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
↵ † A description of the complete county geography changes (metadata) used in the construction and mapping of SoVI can be found at www.cas.sc.edu/geog/hrl/SHELDUSmetadata.html. Alaska counties provide a unique challenge for historical analyses. Gaining statehood rather late (1959), the early census divisions were significantly altered to boroughs and census areas in the 1980s and further changed to boroughs and counties in subsequent censuses. The geographic areas were changed as were the names and identifying codes. For example, in the 1990s, Yakutat borough was formed from pieces of other divisions. These changes are noted in the U.S. Census documentation of changing geography (www.census.gov/geo/www/tiger/ctychng.html).