This paper offers a descriptive account of Twitter (a micro-blogging service) across four high profile, mass convergence events-two emergency and two national security. We statistically examine how Twitter is being used surrounding these events, and compare and contrast how that behavior is different from more general Twitter use. Our findings suggest that Twitter messages sent during these types of events contain more displays of information broadcasting and brokerage, and we observe that general Twitter use seems to have evolved over time to offer more of an information-sharing purpose. We also provide preliminary evidence that Twitter users who join during and in apparent relation to a mass convergence or emergency event are more likely to become long-term adopters of the technology.

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Designing and deploying groupware is difficult. Groupware evaluation and design are often approached from a single perspective, with a technologically-, individually-, or socially-centered focus. A study of Groupware Calendar Systems (GCSs) highlights the need for a synthesis of these multiple perspectives to fully understand the adoption challenges these systems face. First, GCSs often replace existing calendar artifacts, which can impact users' calendaring habits and in turn influence technology adoption decisions. Second, electronic calendars have the potential to easily share contextualized information publicly over the computer network, creating opportunities for peer judgment about time allocation and raising concerns about privacy regulation. However, this situation may also support coordination by allowing others to make useful inferences about one's schedule. Third, the technology and the social environment are in a reciprocal, co-evolutionary relationship: the use context is affected by the constraints and affordances of the technology, and the technology also co-adapts to the environment in important ways. Finally, GCSs, despite being below the horizon of everyday notice, can affect the nature of temporal coordination beyond the expected meeting scheduling practice.

Social media and other online communication tools are a subject of great interest in mass emergency response. Members of the public are turning to these solutions to seek and offer emergency information. Emergency responders are working to determine what social media policies should be in terms of their "public information" functions. We report on the online communications from all the coastal fire and police departments within a 100 mile radius of Hurricane Sandy's US landfall. Across four types of online communication media, we collected data from 840 fire and police departments. Findings indicate that few departments used these online channels in their Sandy response efforts, and that communications differed between fire and police departments and across media type. However, among the highly engaged departments, there is evidence that they bend and adapt policies about what constitutes appropriate public communication in the face of emergency demands; therefore, we propose that flexibility is important in considering future emergency online communication policy. We conclude with design recommendations for making online communication media more "listenable" for both emergency managers and members of the public.

We analyze microblog posts generated during two recent, concurrent emergency events in North America via Twitter, a popular microblogging service. We focus on communications broadcast by people who were "on the ground" during the Oklahoma Grassfires of April 2009 and the Red River Floods that occurred in March and April 2009, and identify information that may contribute to enhancing situational awareness (SA). This work aims to inform next steps for extracting useful, relevant information during emergencies using information extraction (IE) techniques.