Brief Report
Number of Warning Information Sources and Decision Making During Tornadoes

https://doi.org/10.1016/j.amepre.2014.09.007Get rights and content

Background

Taking proper protective action upon receiving tornado warnings is critical to reducing casualties. With more warning information sources becoming available, how the number of such information sources affects decision making should be quantitatively investigated.

Purpose

To examine how the number of warning information sources affected individuals’ decisions to take protective action during tornadoes.

Methods

A telephone survey using random sampling was conducted in 2012 with residents in Tuscaloosa AL and Joplin MO, resulting in a working sample of 782 respondents. Both cities were struck by violent tornadoes (Enhanced Fujita Scale [EF]4 and EF5) in 2011. The analysis was conducted in 2013.

Results

Logistic regression analysis showed that relative to having only one warning information source, having two and three or more warning information sources significantly increased the odds of taking protective action in Joplin but not in Tuscaloosa; having three or more sources had a significantly stronger effect on taking protective action in Joplin than in Tuscaloosa. Having an emergency preparation plan in both cities and being white in Tuscaloosa significantly increased the odds of taking protective action, whereas being divorced in Joplin reduced these odds.

Conclusions

Receiving warnings from more warning information sources might be more beneficial in places with less previous exposure to tornadoes and for populations with lower awareness of a potential tornado and higher probability of receiving no warnings. Emergency management agencies and public health officials should give priority to these places and populations when formulating disaster mitigation decisions and policies.

Introduction

Increasingly more sources are available to communicate warnings of natural hazards with increasing access to social media and mobile applications.1 The greater number of warning information sources (WISs) could possibly promote compliance to warnings because it reduces threat denial and increases the perception and personalization of risk.2, 3 However, little empirical evidence exists about the association between the number of WISs and protective action being taken.

Tornadoes, especially violent ones, present great threats to people’s health and lives.4, 5 Total fatalities caused by tornadoes from 1950 to 2011 in the U.S. amount to 5,641, more than those by hurricanes and earthquakes combined.6 Taking proper protective actions upon receiving tornado warnings, such as taking shelter, is a key factor to reducing casualties.7, 8 With continuous improvements in technology allowing for longer lead time, a better understanding of social mechanisms and individual behaviors centering on responses to warnings is especially important.9, 10

In this study, the effect of WISs on the likelihood of taking protective action was investigated with two violent tornadoes in 2011: an Enhanced Fujita Scale (EF)4 tornado that occurred in Tuscaloosa AL and an EF5 tornado in Joplin MO. Both storms were properly forecasted and warned by the National Weather Service but caused extremely high casualties, with more than 60 fatalities and 1,500 injuries in Tuscaloosa and 160 fatalities and 1,000 injuries in Joplin.7, 11, 12 This triggered wide discussions about the effectiveness of warning communication.6, 11, 13 In addition, the differences between these two tornadoes in terms of residents’ past experiences with tornadoes, forewarning, storm’s timing, and local preparedness provided opportunities to examine the proposed research question under different social and historic contexts.

Section snippets

Subjects and Survey Instrument

A telephone survey was conducted in October 2012 with respondents aged ≥18 years upon the approval of the IRB of Texas Tech University. Altogether, 1,006 telephone interviews were completed based on about 5,000 telephone numbers randomly selected from the tornado paths (details available upon request). Respondents who did not receive any warning or did not report on their responses were later removed, resulting in a working sample of 782 cases.

Measures

The dependent variable was a dichotomous variable

Results

As shown in Figure 1, about 6% of respondents in Tuscaloosa and 21% in Joplin did not receive any warning. More details are presented in Figure 2.

As shown in Table 1, relative to having one WIS, having two (OR=2.19; 95% CI=1.08, 4.43) or having three or more (OR=2.57; 95% CI=1.31, 5.04) significantly increased the odds of taking protective action in Joplin but not in Tuscaloosa. Having three or more WISs had a significantly stronger effect in Joplin than in Tuscaloosa (OR=3.03; 95% CI=1.06,

Discussion

This study shows that the number of WISs significantly increased the respondents’ likelihood of taking protective action in Joplin but not in Tuscaloosa. Perception and personalization of the risk as influenced by past exposure may explain such a difference between these two cities.16, 17 Between 1995 and 2011, 35 tornadoes were reported in Tuscaloosa County and eight were rated EF2 or higher. In Tuscaloosa County, an EF3 tornado occurred 2 weeks prior to the one for which data were collected

Acknowledgments

Dr. Sara T. Norman, Director of the Earl Survey Research Lab at Texas Tech University, provided valuable assistance in survey design and data collection. This material is based upon work supported in part by the National Science Foundation under grant no. CMMI-1000251. Any opinions, findings, and conclusions or recommendations expressed in this paper are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Jianjun Luo and Daan Liang receive funding

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