Crowd Psychology: Has The Boston Marathon Bombing Ruined Mass Public Events? "Will the masses at NFL events do 'the wave' only in the watchful sights of a police sharpshooter's high-powered rifle? Is tailgating before the game all but nostalgic history? Will major marathons be relegated to a dull repetition of 105 or so loops around a stadium track?" Probably not. But there will be some lasting ill effects, especially for certain groups.
Scientific American 04/16/13