U. Kracalik, I. T„ Widmer. One researcher analyzed New York City tweeters before, during, and after Superstorm Sandy to show that predisaster mobility patterns can indicate the potential range of mobility during a disaster.30 Other indicators of mobility include transit data by bikes,3' buses and subways being made available by hundreds of municipalities.32 Transit data can monitor population flux at different times of day, and provides just one example of open data which cities are releasing that could be valuable for risk assessment. Despite some initial challenges, epidemiological models of the spatial spread of Ebola were developed to model the spread of the virus, and predict its possible development {Figure 11, page 30). These models can help assess the likely routes of infected individuals between populations, predict possible new outbreaks and help focus the delivery of eventual vaccines.