| Prior research on tornadoes has investigated tornado climatology, societal vulnerability, and mitigation techniques. This study is one of the first to combine all three measures to develop a more comprehensive estimate of the vulnerability of counties to tornadoes. Two research questions are posed. First, what is the spatial variability in place vulnerability to tornadoes, and what factors are responsible? Second, how does place vulnerability operate at different scales?; A physical vulnerability index was created using tornado segment data from 1950--2002 for US counties. Social vulnerability indicators culled from the 2000 Census were used to create a social vulnerability index. All county-level variables were standardized, and a factor analysis (principal components analysis) was used to create vulnerability indices from these variables. A county mitigation index was constructed from a number of sources. The place vulnerability of counties was computed as the sum of physical vulnerability plus social vulnerability minus mitigation.; The national assessment of place vulnerability to tornadoes showed considerable geographic variation. As expected, most of "Tornado Alley" was identified as highly vulnerable, but portions of it had low place vulnerability index values. Other counties in the Deep South, Midwest, Florida, Colorado, and urban counties were also highly vulnerable. The place vulnerability index significantly correlated with observed tornado losses, but the strength was only moderate (R = .27).; The case studies (Marion County, IN and Georgetown County, SC) provided details on the nature of vulnerability at a sub-county level. Marion County, IN had a higher place vulnerability score than Georgetown County, SC largely due to more physical risk. Better mitigation offset the risk, but social vulnerability is higher in Marion County. The results of the public surveys provide two consistent findings: older residents were less likely to seek shelter; and African-Americans were less likely to understand the meaning of a tornado watch.; Synthesizing the three main components of place vulnerability provided a more comprehensive view of tornado vulnerability in the U.S. This knowledge is important in determining how to best develop methods for loss reduction. Mitigation efforts can become more cost effective by targeting specific socioeconomic groups in highly vulnerable areas. |
