Facing #emergencies. The linguistic role of keywords, hashtags and retweets in communicating critical events

In recent years, social media platforms have had a tremendous impact on the online world due to their effectiveness in multimodal communication events (Herring 2001). Social media users benefit from the digital nature of such interactions to gather data for different purposes, including discourse-related ones (Zappavigna 2012). Hashtags, in this sense, have proved to be an effective tool that is used to broaden communication but also to prompt real-life actions, especially to face and manage critical or emergency situations (Olteanu et al. 2015). This specific device is more likely to be used effectively on Twitter, a popular micro-blog used as an information aggregator and catalyst for action (Zappavigna 2015). Following previous studies focusing on the same topic (Burnap et al. 2014; Hughes, Palen 2009), the paper examines examples of context-based words and/or purpose-specific hashtags to explore their use by different sets of users with diverse intentions and aims. Twitter data are retrieved by means of real-time data mining tools (Brooker et al. 2016) to create relevant keyword- or hashtag-based sample corpora dealing with emergency situations (Aug – Sep 2017: two terror attacks and a natural disaster) which have caused remarkable media exposure. Data from such corpora identify some relevant words used in such situations, grouped according to several variables such as event-related, channel-dependent or sentiment-based criteria. Furthermore, an aggregated analysis is carried out in order to retrieve the most common patterns used to highlight performativity, thus emphasising the role of purpose-specific communication. Finally, a comparison of aggregated corpora with different tool-specific features (retweets) highlights the importance of such tool-specific devices in magnifying the range of communication effectiveness occurring in a proper 'online discourse community' (Herring 2008).