The Influence of Previous Disaster Experience and Sociodemographics on Protective Behaviors during Two Successive Tornado Events

Authors: Amber Silver and Jean Andrey

Discipline: Geography

Hazard of Interest: Tornado

Methods: Semi-structured interviews and close-ended questionnaires

Key Research Issues:

• This research examines two successive, potentially tornadic events that occurred in Goderich, Ontario, Canada on 21 August 2011 and 24 August 2011.
• The purpose of this socio-behavioral study was to investigate the influence of previous disaster experience on risk perception and response to a low-probability, high-impact disaster.

Key Research Findings:

• Physical cues were the primary motivators of protective action on 21 August 2011, while the Environment Canada tornado warning was the primary motivator on 24 August 2011.
• Respondents were more likely to take protective action during the subsequent storm on 24 August 2011, regardless of whether they were physically present for the tornado on 21 August 2011. This highlights the important influence of indirect disaster experience on hazard perception and response.
• Socio-demographics were not found to influence protective decisions made on 21 August 2011, while gender (female) was related to decision-making on 24 August 2011.
• The intense media coverage of the impacts of the 21 August 2011 tornado may have contributed to a social amplification of risk on 24 August 2011.

Tornado Warning Trade-Offs: Evaluating Choices for Visually Communicating Risk

Authors: Kevin D. Ash et al.

Discipline: Geography

Hazard of Interest: Tornado

Methods: Questionnaire, Mann-Whitney U test, Getis-Ord G*i Hotspot analysis, linear-by-linear chi-square test, GIS

Key Research Issues: Do deterministic-style and probabilistic-style tornado warning graphics elicit different fear responses and protective action intentions?

Key Findings:

• The deterministic warning showed higher fear and protective action responses than the probabilistic-style warnings

• Participant responses dropped off more sharply near the edge of the deterministic warning

• Probabilistic warnings elicited clusters of high fear and protective action responses coincident with the higher probabilities of a tornado, which aided in understanding the direction of movement implied by the warning shape and color patterns

• The cluster of high responses for the deterministic warning was near its centroid and did not clearly indicate that viewers understood the direction of movement from the shape alone