Empirical analysis of volunteer convergence following the 2011 tornado disaster in Tuscaloosa, Alabama

Volunteer convergence refers to the mass movement of volunteers toward affected areas following disaster events. Emergency management professionals sometimes refer to volunteer convergence as “the disaster within the disaster,” which is an indicator of the tremendous challenge that managing the post-disaster influx of spontaneous volunteers presents. In order to develop effective strategies for managing volunteer convergence, it is imperative that emergency managers and coordinators understand the nature of convergence from a quantitative perspective. This paper presents a case study of volunteer convergence following the April 2011 tornado disaster in Tuscaloosa, Alabama, and represents the first academic study to rigorously analyze volunteer convergence data. Specifically, we characterize selected stochastic variables that are relevant to volunteer task assignment within the context of a disaster relief warehouse environment using data collected during tornado relief efforts in May 2011. Time series analysis and a hierarchical clustering method based on the Kruskal–Wallis test revealed both non-stationarity and non-homogeneity in the data with respect to time of day, day of the week, and number of weeks past the disaster event. We also discuss the implications of our findings with respect to modeling relief center convergence as a queuing system.