Abstract
Social media, also called Web 2.0, is a generic term used to talk about applications that allow users to create, manipulate, and disseminate content as much as possible in real time. These applications allow for several possibilities that range from involvement to participation, communication, and collaboration of users. They allow everyone with minimal access to the Internet to publish, share, review, comment, and post items, such as mentions, comments, information, videos, and photos. In a crisis, social media becomes a double-edged sword. It can play an essential role during the prodromal, acute, chronic, and resolution phases of natural disasters and human-made crises. Social media can also be at the origin of the crisis or the reason for its amplification. Social media facilitates an increase of interactions between main actors at the center of a crisis. This chapter combines social media content analysis (opinion detection and sentiment analysis) with network analysis (ego network analysis) and nodes centrality assessment to critically evaluate how social media affects the crisis management process.