Actionable Information during Extreme Events -- Case Study: Warnings and 2011 Tohoku Earthquake

Social media is rapidly becoming an integral part of modern society. People use social media as a channel of communications with each other, a targeted group or a general public. Concurrently, researchers are studying this channel of communications in an attempt to link the characteristics of the message, such as content, sender-receiver, etc. to the behavior of those using this media. The focus of the research reported herein is to analyze human behavior in response to actionable information in the context of an extreme event. A specific case of actionable information presented in this paper is recommendations to take actions to reduce the chance of harm from the consequences of an extreme event i.e. an alert or warning. Authorized officials via multiple channels of communication issue the warnings to the public. At present, social media is not used universally as an official channel of communication. There is still no clear consensus among emergency management organizations on how the social media can be utilized to disseminate warnings to the public. The first step is to understand people's behaviors on social media in response to actionable information during extreme events. In order to understand people's behaviors on social media, we need to understand the content of their messages and how the messages travel through social media. The paper focuses on identifying hidden key actors (individual/organizations) using advanced social network analysis techniques. Additionally, the paper examines the formation of the cohesive groups in the network and the role of the key actors in those groups. Our conclusion is that the key actors play an important role in diffusion of actionable information. The diffusion begins with central and prominent actors and diffuses through the `gatekeepers' of information to the rest of the network. The key actors exhibit intentions to take a prescribed action and urge others to do so. Finally, the key actors play in important role of bridging cohesive groups in the network in order to facilitate the diffusion of actionable information.