Social media and public information management: the September 2009 tsunami threat to New Zealand. [Paper in themed section: The Victorian Bushfires and Other Extreme Weather Events: Case Studies in Crisis, Culture and Communications. North, Louise and Bainbridge, Jason (eds).]

Social media are often the first point of reference for emergency management information for many people, including the traditional media. As social media and online community networks produce early event awareness, and ongoing information and guidance, they can create an asynchronous disjunction with information provided by official Emergency Management (EM) channels. This article explores how social media and other information communication technologies act as ‘back channels' of communication, assaying, analysing and commenting upon official emergency management messages as they are disseminated. The research shows how official messaging in the early stages of a national (tsunami) warning is characterised by an ‘information and guidance lag’ period created by the institutionalised requirement of scientific assessment and validation in accordance with organisational protocols in the inherently uncertain business of predicting the path and impact of a tsunami. The research suggests that, despite concern by officials about the legitimacy of information shared through social media, such technologies are gaining prominence in the disaster arena. The methodology uses an analysis of social media conversations and posts, official documents reviewing the tsunami threat and its aftermath, and academic publications. This research will interest academics and EM practitioners who are concerned with improving Public Information Management (PIM).