Making decisions at the right time and in the right way is vital in dealing with extreme events. However, uncertainties and severe time constraints usually make the tasks hard and stressful. Since catastrophes are not frequent events in our lives, prior practice is essential to increasing preparedness. In accordance with its rapid development and extensive dissemination, information communication technology (ICT) has been recognised as an indispensable instrument, not only to assist onsite activities of professional emergency responders, but also to support collaborative actions of a wide-range of stakeholders for effective preparedness. This research intends to explore the feasibility of workshop-style decision-making exercises on the basis of scenarios of extreme events, and to examine the role of ICT in mediating the interactive processes during a workshop. A comparative approach between the UK and Japan was employed to find similarities and differences in the way of identifying major issues, proceeding to a discussion, and reaching a decision on which course of action to take. Interviews with Japanese and British experts, including researchers and practitioners, were conducted to develop realistic scenarios and to hear their opinions about the use of ICT in the crisis preparedness context. Experimental face-to-face (FTF) workshops and online workshops were respectively organised for Japanese and British research participants to examine the applicability of the scenario method under these two different methods of communication. Complementary online workshops were also conducted for Japanese and British practitioners to obtain practical feedback on the idea of scenario-based online workshops. The main finding of this study was that scenario-based exercises are beneficial regardless of the nationality or the methods of communication in decision problems in which individuals have no prior experience. The most noteworthy finding was that scenario-based online workshops are unlikely to be argumentative and results-oriented under certain conditions, such as complexity of issues and tasks, amount of time spent by participants, degree of facilitation and type of technology used. This finding indicates that online exercises require different strategies from FTF exercises. In theoretical aspects, this study provides a foundation for theory formation regarding scenario methods. In addition, this work contributes to further development of online communications based on the comparison with FTF communications. In practical terms, the examination of the scenario method and use of ICT offers methodological alternatives in order to implement more robust preparedness.