Since 1950, tornadoes have accounted for nearly one third of disaster-related fatalities in the United States, the third highest after floods and lightning. The largest share of fatalities occurred in the state of Texas, which also accounts for about 7 percent of the overall property damage from tornadoes. An increasing proportion of tornadoes occur during tornado outbreaks, which were responsible for almost 80 percent of tornado-related fatalities in the United States between 1972 and 2010. Although the relationships between tornado severity, economic damage, and injuries and fatalities are generally well understood, few studies examine how injuries and fatalities are affected by a single tornado versus those that are part of a tornado outbreak. This work analyzes a data set of Texas tornadoes that occurred between January 1973 and January 2007, through nonparametric statistical and spatial analyses, examining the associations between tornado severity, number, and geography of occurrence as related to direct injuries and fatalities in severe weather events. Results indicate that tornado severity exacerbates causalities, but outbreaks do have some effect as well. These findings have potential implications for improving forecasting, warning, and preparedness for tornado outbreaks, which could be critical to reducing deaths and injuries from future tornadoes.

自1950年以来，龙卷风已占美国因灾害造成的死亡的近三分之一，仅次于洪水和闪电。死亡人数最多的州是德克萨斯州，它也占龙卷风造成的全部财产损失的约7％。在龙卷风爆发期间发生的龙卷风比例越来越高，在美国到1972年至2010年期间，龙卷风造成了近80％的龙卷风相关死亡。尽管人们普遍了解龙卷风的严重程度，经济损失以及伤害和死亡之间的关系，很少有研究检查一次龙卷风与龙卷风爆发的伤害和死亡的影响。这项工作分析了1973年1月至2007年1月之间发生的德克萨斯龙卷风的数据集，通过非参数统计和空间分析，检查龙卷风严重程度，数量和发生的地理位置之间的关联，这些关联与严重天气事件中的直接伤害和死亡相关。结果表明，龙卷风的严重性加剧了因果关系，但暴发确实也有一定影响。这些发现对改善龙卷风爆发的预报，预警和准备工作具有潜在的意义，这对于减少未来龙卷风造成的伤亡至关重要。