Impacts, assessments, and responses: Interdisciplinary perspectives on tornadoes
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The impacts of disasters should be examined from the aspects of natural phenomenon and human reactions. This dissertation builds on an interdisciplinary perspective that aims to reduce the negative social and economic impacts and enhance society's resilience to disaster. It consists of three papers on three studies that are independent and intertwined at the same time. The data are from two 2011 violent tornadoes that were rated as the costliest and second costliest tornadoes in U.S. history and together were responsible for 223 death and $5.2 billion in economic losses. The first study reconstructs near-surface wind field for the Joplin Tornado of 2011 based on the post-tornado damage survey of residential buildings. This study innovatively uses a translating analytical vortex model and fits the model with the wind speeds estimated from the degrees of damage of 4,166 buildings. It’s found that the peak wind field produced by the model agrees reasonably well with the observed damaged pattern. The simulated tornado model could be used to estimate the time history of wind speed and direction at any given point, as well as helping to better understand the relationship between tornado parameters and wind field structures. The second study develops an Enhanced Remote-Sensing (ERS) scale to improve the accuracy and efficiency of the use of remote-sensing images of residential buildings to predict their overall damage conditions. The new scale, by incorporating multiple damage states observable on the remote sensing imagery, substantially reduces measurement errors and increases the amount of information retained. Analysis of 1,400 residential buildings after the Joplin EF5 tornado shows that remote-sensing imagery assessed with ERS could precisely predict ground level damage. This offers strong empirical evidence for the effectiveness of the ERS scale and remote sensing technology in post- damage assessment for tornadoes and for other wind events, such as hurricanes and straight-line winds. The third study investigates how the number of tornado warning information sources affects people’s decision to take protective action. It also examines social disparity and contextual differences in the number of sources that people have access to. The data come from a telephone survey of more than 1,000 residents of Joplin and Tuscaloosa approximately one year after the EF5 and EF4 tornadoes. This study addresses the important but rarely examined association between the number of sources of warnings received and taking protective action at the individual level. This study also directs attention to social disparity and contextual differences in people’s access to tornado warnings. The findings in this study provide partial support for the positive effect of having more warning information sources and identify populations who are vulnerable in the access to warning information sources. Social disparity and the number of warning information sources play a more consequential role in places that are less prepared for storms. Thus, it is crucial for emergency management agencies and public health officials to target those places when allocating limited resources to promote protective action and reduce casualties. These three studies and their findings make significant contributions to the efforts of risk analysis and modeling within an overarching framework that takes into consideration the influences of social, economic, and building environment on individuals and communities. Thus, it will help insurance companies, emergency officers, and policy makers to assess potential losses and better prepare for future disasters in order to enhance resilience to these disasters.