The Spacetime Continuum: Using Spatio-temporal Filtering Techniques to Revisit Rumor Theory

A characteristic feature of disasters is the disruption of routine activities in a society. This disruption spurs novel activity from a variety of social units, from organizations to public officials to ordinary citizens. A major component of this response is informal communication among the public and this public communication increasingly occurs in online settings. Much of this online, informal communication falls under the formal definitions of rumoring and I harness the precision of Twitter's timestamped, geolocated messages to probe the spatial and temporal features of rumoring. A challenge of relying on streams of online data is finding signal amid the overwhelming volume of activity. To overcome this obstacle I use what is known about the spatial and temporal characteristics of both rumoring and disaster-related information transmission to develop a spatio-temporal filtering approach for measuring rumoring. I demonstrate in the first chapter that this approach offers strong increases in signal of hazard-related rumoring activity across a variety of events, both natural and anthropogenic. The results shed light onto the distribution of rumoring activity across large spatial scales. In the second chapter I use the same spatio-temporal filtering approach to identify surges in signal of content of hazard-related rumoring as I look for evidence of topical convergence and content evolution throughout the rumoring process. In the third chapter I test a variety of rumor theories by measuring which features of each U.S. county---its demographics, history of tornado events, and volume interpersonal ties to the tornado-affected county---determine its propensity to rumor about severe tornado events. Using data whose spatio-temporal precision and scope (both in geography and variety of events) have historically been infeasible, this dissertation makes several valuable contributions to rumor theories.