Network analysis has emerged as a powerful way of studying phenomena as diverse as interpersonal interaction, connections among neurons, and the structure of the Internet. Appropriate use of network analysis depends, however, on choosing the right network representation for the problem at hand.

Significance: We examine the effects of an uneven population distribution on the spread of the COVID-19 disease spread, using a diffusion model based on interpersonal contact networks. Taking into account spatial heterogeneity, the spread of COVID-19 is much “burstier” than in standard epidemiological models, with substantial local disparities in timing and severity and long lags between local outbreaks. We show that spatial heterogeneity may produce dramatic differences in social exposures to those with the illness, and may stress health care delivery systems in ways that are not well captured by standard SIR-like models.

Significance: Online social networks (OSNs) enable time-resolved measurement of communication behavior during disasters, making it possible to probe the mechanisms by which messages are amplified or suppressed with precision unattainable by traditional data sources. To our knowledge, this research provides the first systematic study of the factors predicting the social amplification of risk communication in OSNs by examining the retransmission of official messages across five hazards. Our findings demonstrate the respective impacts of sender characteristics, message content, and message style in determining whether an official message will be passed on during an emergency, as well whether these vary across hazards. These results contribute to the evidence base for policies guiding the delivery by emergency management organizations of lifesaving information to the public.

Using archival materials obtained from the Port Authority of New York and New Jersey, we analyze networks of communication and interaction among responders to the World Trade Center disaster. Our findings indicate substantial variability in individual radio communication system usage, with both communication volume and number of partners exhibiting distributions with long upper tails. Responder communication patterns are well-described by a fairly simple four-role structure and exhibit substantial similarity across responder groups (both specialist and non-specialist). Occupancy of coordinating roles is influenced by formal institutional status, but the vast majority of hub role occupancy appears to be emergent in character. Examination of both radio transcripts and police reports suggests that much of the communication among WTC responders is centered on problems of spatial reasoning and peer location, possibly providing an explanation for the importance of improvised coordination at the event site. Although these problems appear to have posed substantial challenges for responders at Ground Zero, we find the global communication/interaction network among Port Authority officers to be fairly well-connected, with little evidence of large-scale fragmentation (despite perceptions to the contrary). Implications of these findings for the modeling of communication networks in emergency settings are discussed.