Economic Losses and Extreme Tornado Events
Advisor: Dr. Susan L. Cutter
Research on tornado impacts has previously focused mainly on analyzing the deaths and injuries associated with tornadoes. While economic loss from multiple hazards is a well-researched field, little has been done to assess the economic losses sustained during tornado events. Additionally, the literature regarding the Enhanced Fujita scale’s comparability to the Fujita scale is limited. This research aims to add to the literature by statistically analyzing the two tornado scales, determining the movement of tornadoes over time using a cluster analysis, comparing the location of extreme tornadoes to those which produce extreme loss, and looking at the statistical relationship between extreme tornadoes and extreme loss.
This study uses tornado data collected from the National Climatic Data Center to analyze tornadoes in the continental United States from 1990-2012. Tornadoes studied were limited to those that included a GPS location and any estimated property or crop damage, no matter how small. Loss estimates were adjusted for inflation using the Consumer Price Index and again using a county Gross Domestic Product method developed by Ash, Cutter, and Emrich (2013).
The results of this thesis conclude that the Enhanced Fujita and Fujita scales are statistically different from one another for lower-rated (0-2) tornadoes, but not for higher-rated ones (3-5). Geographically, clusters of tornadoes have moved northward and eastward over time. This research also demonstrates that the location of extreme tornadoes is not always the same as the location of tornadoes producing extreme loss. Finally, this research shows that economic losses from F/EF5 tornadoes have a greater mean, range, and standard deviation than those from F/EF4 tornadoes.
From a research perspective, this thesis demonstrates the importance of distinguishing between tornadoes rated on the Fujita and Enhanced Fujita scales, since they cannot be considered equivalent to one other. From a policy perspective, local mitigation plans would be improved by taking into account the historical movement of tornado clusters northward and eastward as identified here. Finally, this research has identified that it is not just the extreme tornadoes that deserve mitigation efforts, but also lower-rated tornadoes that are capable of producing millions of dollars in damage.