The Crisis Informatics of Online Hurricane Risk Communication by Melissa J. Bica B.S., Santa Clara University, 2014 M.S., University of Colorado Boulder, 2017 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Computer Science 2019 This thesis entitled: The Crisis Informatics of Online Hurricane Risk Communication written by Melissa J. Bica has been approved for the Department of Computer Science Prof. Leysia Palen (chair) Prof. Kenneth M. Anderson Dr. Julie L. Demuth Prof. Brian C. Keegan Prof. Clayton Lewis Date The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline. IRB protocol #19-0077, 19-0109 iii Bica, Melissa J. (Ph.D., Computer Science) The Crisis Informatics of Online Hurricane Risk Communication Thesis directed by Prof. Leysia Palen Social media are increasingly used by both the public and emergency management in disasters. In disasters arising from weather-related hazards such as hurricanes, social media are especially used for communicating about risk in the pre-disaster period when the nature of the hazard is uncertain. This dissertation explores the sociotechnical aspects of hurricane risk communication, especially information diffusion, interpretation, and reaction, as it occurs on social media between members of the public and authoritative weather experts. I first investigate the kinds of hurricane risk information that were shared by authoritative sources on social media during the 2017 Atlantic hurricane season and how different kinds of infor- mation diffuse temporally. This motivated a deeper qualitative analysis in a second study on the interactions between laypeople and experts around authoritative yet uncertain risk representations and how the mediation of the representations on social media impacts people’s risk interpretations. Risk communication, however, is not only concerned with what authorities/experts see as the im- portant message to get out and how people respond to those messages, but also about how people conceive of risk more independently. The issues that lay people are concerned about, as understood from their social media posts, are not necessarily the issues that authoritative sources are concerned about or would share in their risk messages. Thus, the third study takes this perspective and in- vestigates what people do under highly constrained situations while preparing for and experiencing a multi-hazard hurricane, revealing the liminality of such experiences and the supportive role of social media. Throughout the research, social media is both a tool used by stakeholders for risk information sharing and communication purposes, but also a source of data that allows for analysis of these activities in situ, an affordance that not many other methods of data collection offer, espe- cially in time- and safety-critical hazard events like hurricanes. Using social media to study these iv issues contributes new ways of thinking about communicating hurricane risk and of measuring the effectiveness of such communication as well as novel findings that could benefit national weather agencies’ operations. v Acknowledgements This dissertation came together with the support of many people. I first want to thank my advisor, Leysia Palen. Thank you for guiding and motivating me through this journey. I aspire to both your expertise in research and effectiveness in mentoring. To my committee members, Ken Anderson, Julie Demuth, Brian Keegan, and Clayton Lewis, thank you for your support and guidance. I appreciate the influence each of you has had in helping to shape this dissertation. To my colleagues at NCAR, especially Rebecca Morss, Jen Henderson, Heather Lazrus, and Olga Wilhelmi, among many others I have met with over the years, thank you for welcoming me into your research community and helping to make my work meaningful at a practical level. To the undergraduate research assistants who have worked with me on various parts of the research, Jamie Ackerson, Hande Batan, Jason Cummings, Marissa Kelley, Rohan Ramnani, Joy Weinberg, and Steven Yatko, thank you for your important contributions to this work. I know for many of you it meant reading tweets for hours on end, and I am so grateful for your time and hard efforts. To my friends and colleagues, Jennings Anderson, Marina Kogan, and Robert Soden, I have so appreciated our friendship over the years. Our time working at the “big table” and using walkie talkies between our offices are some of my best memories at CU. I am also grateful to my colleagues and labmates Jim Dykes and Gerard Casas Saez for your collaborations. To my former advisors at Santa Clara University, Silvia Figueira and Ruth Davis, thank you for being such wonderful mentors, for being the first professors to introduce me to computer science vi and engineering, and for encouraging me to pursue graduate school! Finally, I want to thank my family and friends. To my parents, Ruth and Vito, especially, thank you for your unwavering support and encouragement through all the ups and downs. And to Jared, thank you for being with me and believing in me every step of the way. Contents Part I: Introduction & Background 1 1 Introduction 2 1.1 Communication of Hurricane Risk Information . 4 1.2 Overview of Dissertation . 6 1.3 HCI/CSCW Perspective on Risk Communication . 7 1.4 Overview of Research Studies . 11 1.5 Overview of Methodology . 13 1.6 Organization of Dissertation . 14 2 Background Literature 16 2.1 Disaster Sociology . 16 2.1.1 Convergence in Disasters . 16 2.1.2 Temporality of Disasters . 17 2.2 Crisis Informatics . 18 2.2.1 Early Crisis Informatics Research . 18 2.2.2 Social Media . 20 2.3 Risk Communication . 27 2.3.1 Social Media Studies of Risk Communication . 29 2.3.2 Hurricane Risk Commuication . 31 2.4 Hurricanes . 33 2.4.1 Overview of Hurricanes and their Impact in the US . 33 2.4.2 Forecast and Risk Images . 35 2.4.3 Evacuation . 38 Part II: Hurricane Risk Imagery Diffusion 41 Prologue 42 3 Communicating Hurricane Risks: Multi-Method Examination of Risk Imagery Diffusion 44 3.1 Introduction . 44 3.2 Background . 47 3.2.1 Perceptions about Hurricane Risk Images . 48 3.2.2 Imagery & Risk Studies in Crisis Informatics . 49 vii viii 3.2.3 Diffusion via Social Media . 50 3.3 2017 Atlantic Hurricane Season . 50 3.4 Study 1: Image Collection & Coding . 51 3.4.1 Data and Methods . 51 3.4.2 Hurricane Risk Images: What Does (Not) Diffuse . 55 3.5 Study 2: Defining & Measuring Diffusion . 56 3.5.1 Method . 57 3.5.2 Diffusion by Risk Image Category . 58 3.5.3 Diffusion by Authoritative Source Category . 61 3.6 Study 3: Qualitative Analysis . 62 3.6.1 Method . 62 3.6.2 Forecast Risks: Cone of Uncertainty . 63 3.6.3 Observational Risks: Radar/Satellite . 64 3.6.4 Preparedness Information: Evacuation . 64 3.6.5 Past Hurricane Graphics . 65 3.6.6 Political and Off-Topic Diffusion . 66 3.7 Discussion and Implications . 66 3.7.1 Design Implications . 67 3.7.2 Methodological Contributions . 68 3.7.3 Policy Implications . 69 Part III: Interpretation of Risk and Uncertainty Information 71 Prologue 72 4 Accuracy and Ambiguity: How Experts and Laypeople Cooperatively Make Sense of Hurricane Risk Imagery 74 4.1 Introduction . 74 4.2 Hurricane Models and Forecasts . 77 4.3 Interaction with Representations of Uncertainty . 78 4.3.1 Visualizing Risk and Uncertainty . 79 4.3.2 Risk Communication, Perceptions, and Response . 81 4.4 Data Collection and Analysis . 82 4.4.1 2017 Atlantic Hurricane Season . 82 4.4.2 Method . 82 4.5 Public-Authoritative Interactions on Spaghetti Plot Social Media Posts . 86 4.5.1 Spaghetti Plot Literacy . 87 4.5.2 Localizing Risk . 91 4.5.3 Broader Sensitivity to the Larger Region . 93 4.5.4 Communicative Responsibilities of Authoritative Sources . 96 4.6 Discussion and Implications . 106 4.6.1 Implications of the Research . 108 4.7 Conclusion . 110 ix Part IV: Reactions to Risk in Highly Constrained Situations 112 Prologue 113 5 The Liminality of Uncertainty: What Happens When Social Media is Employed by Those in Highly Constrained Disaster Situations 116 5.1 Introduction . 116 5.1.1 Vulnerabilities as Constraints . 119 5.1.2 Situated Accounts of Liminality . 120 5.2 Research Site and Study Method . 122 5.2.1 Event Description . 122 5.2.2 Overlapping Tornadoes and Flash Floods . 123 5.2.3 Data Collection and Analysis . 124 5.3 Using Social Media When Highly Constrained . 125 5.3.1 Seeking Financial Help . 126 5.3.2 Negotiating Structural Power Dynamics . 130 5.3.3 Confronting Institutional Demands . 134 5.3.4 Publicizing Action . 139 5.4 Discussion . 140 5.5 Conclusion . 143 Part V: Discussion & Implications 144 6 Discussion 145 6.1 Discussion of Research Studies and Implications . 145 6.2 Additional Practical Implications . 152 6.3 Contributions of Resources to Future Research . 155 Bibliography 157 Appendix A Risk Image Coding Scheme 174 Tables Table 2.1 The eight stages of disaster. 17 3.1 Counts of Twitter accounts and risk.