Patrick Meier pointed out a recent paper in the top-tier journal Nature that studies the information flow during emergencies based on cell phone usage and compared them with communication patterns of mobile phone users outside the affected area. Understanding the communication patterns of mobile phone users can help to understand on how situational awareness spreads during a disaster.
The graphs simply present the change in call volume of mobile phone users for four events. Three of them are a crisis event and the fourth one is a non-emergency event. The set of users directly affected by a crisis is labeled G0 while users they contact during the emergency are labeled G1.
Note that G1 users are not affected by the crisis. Since the study seeks to assess how G1 users change their communication patterns following a crisis, one logical question is this: do the call volume of G1 users increase like those of G0 users?
It is quite interesting to see that the communication patterns varies depending on the event. The study is very useful for those (e.g., disaster authorities) who try to figure out how information spreads in a disaster event (e.g., to warn or inform the population).
In sum, a crisis early warning system based on communication patterns should seek to monitor changes in the following two indicators: (1) Volume of Call Backs; and (2) Deviation of Call Backs from baseline. Given that access to mobile phone data is near-impossible for the vast majority of academics and humanitarian professionals, one question worth exploring is whether similar communication dynamics can be observed on social networks like Twitter and Facebook.