Social media has become an integrated part of human communication, both as a means to establish and maintain social relationships, and as a means of sharing and co-creating information. Social media comes with an array of possibilities for individuals as well as organizations, corporations, and authorities. Within the field of crisis communication, social media possibilities such as online sharing and social networking have had an impact on the way crisis information is disseminated and updated. This paper addresses the issues related to using social media for communicating crisis information and broadcasting alert messages to the general population, discusses the role of social media in future pan-European crisis alerting, and presents a prototype system demonstrating the possibilities. An extensive systematic literature review was carried out to identify factors that affect the use of social media for alerting and warning. These factors were mirrored in experiences, collected through interviews, obtained by emergency management organizations in three European countries (Sweden, Czech Republic, and Spain). The factors finally form the basis for suggestions and recommendations regarding the design of technological tools for both communication and information collection to serve as an integral part of a future pan-European crisis alerting system.