Society For Risk Analysis Annual Meeting 2017

Session Schedule & Abstracts

* Disclaimer: All presentations represent the views of the authors, and not the organizations that support their research. Please apply the standard disclaimer that any opinions, findings, and conclusions or recommendations in abstracts, posters, and presentations at the meeting are those of the authors and do not necessarily reflect the views of any other organization or agency. Meeting attendees and authors should be aware that this disclaimer is intended to apply to all abstracts contained in this document. Authors who wish to emphasize this disclaimer should do so in their presentation or poster. In an effort to make the abstracts as concise as possible and easy for meeting participants to read, the abstracts have been formatted such that they exclude references to papers, affiliations, and/or funding sources. Authors who wish to provide attendees with this information should do so in their presentation or poster.

Common abbreviations

Risk Communication and Severe/Extreme Weather

Room: Salon 2   10:30 am–12:10 pm

Chair(s): Gina Eosco

Sponsored by RIsk Communication Specialty Group

W2-K.1  10:30 am  Perceptions of risk and vulnerability following exposure to a major natural disaster: The 2013 Calgary flood . Tanner A*, Arvai J; University of British Columbia, University of Michigan

Abstract: Many studies have examined the general public’s flood risk perceptions in the aftermath of local and regional flooding. However, relatively few studies have focused their attention on large-scale events that affect tens of thousands of people within an urban center, and that garner significant local and international media attention. Likewise, in spite of previous research on flood risks, unresolved debates persist regarding the variables that might influence perceptions of risk and vulnerability, along with management preferences. In light of the opportunities presented by these knowledge gaps, the research reported here examined public perceptions of flood risk and vulnerability, and management preferences within the City of Calgary in the aftermath of extensive and high-profile flooding in 2013. Our findings, which come from an online survey of residents, reveal that direct experience with flooding is not a differentiating factor for risk perceptions when comparing evacuees with non-evacuees who might all experience future risks. However, we do find that judgments about vulnerability—as a function of how people perceive physical distance—does differ according to one’s evacuation experience. Our results also indicate that concern about climate change is an important predictor of flood risk perceptions, as is trust in government risk managers. In terms of mitigation preferences, our results reveal differences in support for large infrastructure projects based on whether respondents feel they might actually benefit from them.

W2-K.2  10:50 am  Effect of risk and protective decision aids on flood preparation in vulnerable communities. Wong-Parodi G*, Fischhoff B, Strauss B; Carnegie Mellon University and Climate Central

Abstract: Although the risks of flooding demand responses by communities and societies, there are also many cost-effective actions that individuals can take. We examine two potential determinants of such adoption: individual predisposition to act and the impact of decision aids that emphasize the risk, the actions, both the risks and actions, or neither (control). Respondents were a representative sample of 1,201 individuals in the areas most heavily impacted by Super Storm Sandy, in 2012. We find that individuals who report having taken action previously are more responsive to all messages except for the combined message – which had a positive effect on those who had not acted previously, but a negative effect on those who had. Finding individual differences in propensity to act supports previous results, as does finding that both stating a problem and providing solutions can motivate people who have not acted previously. Finding that a combined message can reduce reported intention for future action among people who have already taken protective measures, is a new, and potentially troubling result. One possible explanation is that the decision aids generally reduced participants’ estimates of flooding risk. Although even those risks were still high enough to motivate action for many participants, those who had already acted may have felt that they had done enough, after reviewing the full picture described in the combined aid.

W2-K.3  11:10 am  Weather forecasters’ use of ensemble-based uncertainty information for communicating risks of extreme weather. Demuth JL*, Morss RE, Jankov I, Alexander C, Alcott T, Nietfeld D, Jenson T; National Center for Atmospheric Research

Abstract: The weather community is leveraging improved understanding of atmospheric processes and observations and enhanced computational ability to develop numerical weather prediction model guidance. Further, due to limited predictability of weather, model ensembles--i.e., guidance from multiple models or that uses different initial conditions--are being developed to generate an envelope of possible future states (i.e., forecasts). These future possibilities are used to provide uncertainty information in the form of deterministic outputs from different ensemble members (e.g., multiple forecasts of precipitation amount), or as statistically post-processed probabilities (e.g., a probability density function of different precipitation amounts). Such ensemble guidance is being developed at increasingly higher spatial and temporal resolutions. This guidance has the potential to offer tremendous value to National Weather Service (NWS) forecasters who assess and communicate the risk of extreme weather. Yet, very little is known about when and how forecasters access, interpret, and use this guidance--especially high-resolution ensemble-based guidance. To address these knowledge gaps, participant observations and semi-structured interviews were conducted with NWS forecasters from several forecast offices throughout the U.S. to elicit data pertaining to risks of heavy precipitation, winter weather, and severe convective weather (e.g., tornadoes, flash flooding). Data were collected about forecasters’ role and forecast process; current use of model guidance and associated verification information; needs for information from high-resolution ensembles; and interpretations of example products from high-resolution ensembles. This presentation will discuss how forecasters do (and do not) use ensemble-based uncertainty information for communicating these different weather risks and the moderating effects of their expertise, experience, cognitive heuristics, and other factors.

W2-K.4  11:30 am  Differing perceptions of hurricanes and nor'easters. Cuite CL*, Hallman WK, Shwom RL, Demuth J, Morss R; Rutgers University

Abstract: While meteorologists name hurricanes, they do not name nor’easters, even though both types of storm can be deadly. Recent studies indicate that named storms may seem more serious to the public, encouraging more protective action. The current research investigates whether, when all other features of a storm are held constant, coastal residents perceive differences in the severity of nor’easters and hurricanes, and whether there are differences in the likelihood of their taking protective action. We conducted an online survey of 1,700 residents of NJ, NY, and CT living in coastal zipcodes. A series of experiments about hypothetical storm scenarios was used to test message variables, including the type of storm (hurricane vs. nor’easter). Respondents were told that there was an evacuation order in their area, and that the storm was expected to be severe. While message comprehension was similar across both the hurricane and nor’easter conditions, we found small but significant effects on a range of other dependent measures. Those who were told the storm was a hurricane were more likely to believe the storm would be severe (p<.05), and they were more likely to say they would evacuate their homes, to recommend to their neighbors that they evacuate, and to say that it is important to evacuate (ps<.001). They were also more likely to say that they would engage in some protective behaviors, such as moving their belongings to a higher location in their home, withdrawing cash from the bank, and boarding up windows (ps<.01). Taken together, these findings provide evidence that people perceive hurricanes as more severe and more likely to require protective actions, even when the details of the storm themselves are identical. This study provides support for naming nor’easters, as well as for educating broadcast meteorologists and emergency management professionals about these small but consistent differences in perceptions between the types of storms.

W2-K.5  11:50 am  Communicating earthquake hazard. Marti M*, Stauffacher M; ETH Zurich

Abstract: Earthquakes are among the most destructive natural hazards on earth and cannot be predicted nor prevented. Worldwide seismological services model, analyze and provide seismic hazard values. These are essential to implement an earthquake resistant building design, the most efficient measure to reduce potential damage. A common means to communicate results and raise awareness for seismic hazard are maps. Up to now, seismic hazard maps were mainly tailored to the needs of primary users like civil engineers, but they are used likewise to communicate with the public. Even though, maps are an established way to illustrate hazards, there is evidence that they are often misconceived. For example, same hazard levels were interpreted differently, depending on the color hues chosen to illustrate them. Besides color settings, textual characteristics, the conceptualization of legends as well as the manner of presentation are influencing how maps are understood. Accordingly, the Swiss Seismological Service at ETH Zurich revised its hazard maps and information material in line with current best practices in map design and text conceptualization. This study analyses, how experts from the building sector and the general public read and understand maps and information provided in this new format. Two workshops with engineers and architects not specialized in seismic retrofitting (N = 26) and a representative online survey with the Swiss population were conducted. Preliminary results show that understanding seismic hazard remains challenging for experts and non-experts. Especially, understanding more detailed results and navigating within the web pages has shown to be very demanding. Despite its interactive map setting, the platform of the Swiss Seismological Service cannot respond to the users’ expectations with respect to the web design known from frequently used applications like for example Google maps.

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