Book Review: In Christchurch, New Zealand, in 2010 and 2011, a series of earthquakes destroyed buildings, caused liquefaction, and deprived survivors of electricity, transport routes, and water. Canterbury University student, Sam Johnson, used Facebook to mobilize other student volunteers (the ‘Student Volunteer Army’, http://www.sva.org.nz), who helped to ameliorate the effects of the earthquakes. With this example in mind of how social media was successively used by local people following a disaster, I was excited by the title of Joseph Bock’s book, which promised insight into the ways that social media might also be used to predict and prevent outbreaks of violence.