Although tsunamis have the potential to be extremely destructive, relatively little research on tsunami messaging has taken place. Discovering whether tsunami warning messages can be written in a way that leads to increased protective response is crucial, particularly given the increased use of mobile message services and the role they play in notifying the public of imminent threats such as tsunami and other hazards. The purpose of this study was to examine the possibility of designing warning messages for tsunamis that improve upon message style and content used by public alerting agencies to date and to gain insight that can be applied to other hazards. This study tested the impact of tsunami messages that varied in length and content on six message outcomes—understanding, believing, personalizing, deciding, milling, and fear. Relative to the short message, revised messages resulted in significantly more understanding and deciding, known precursors to taking protective action under threat. The revised message also resulted in significantly more fear, which is believed to influence behavioral intentions. Findings suggest that shorter messages may not deliver enough content to inform message receivers about the threat they face and the protective actions they should perform. Longer messages delivered with more specific information about the location of impact, threat-associated risks, and recommended protective actions were associated with better message outcomes, including quicker intended response. Recommendations for future tsunami warnings are provided.

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Published in Weather, Climate, and Society, v. 10, no. 1, p. 75-87.

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This research was supported by the National Science Foundation under Grant OCE 1331600.