Emotional responses and perceptions of false alarms in flood warnings and their impact on evacuation action in the Kyushu Region, Japan

Repeated false alarms for adverse weather events can undermine public trust, potentially leading to a reluctance in taking appropriate actions, such as evacuation. Therefore, understanding the mechanisms by which false alarms influence perceptions and actions is essential for building socially effective early warning systems (EWS). We aimed to examine perceptions, emotions, and actions regarding false flood warnings in Japan. Specifically, we investigated (1) people’s definition of hits; (2) emotional responses toward false alarms; (3) the effect of the false alarm ratio (FAR) on the perceived FAR (pFAR) and the heterogeneity of this effect according to participants’ definition of hits; and (4) the effect of pFAR on evacuation action and the heterogeneity of this effect according to the emotional responses toward false alarms. We used municipality-level FAR data newly derived for this study and questionnaire data collected from residents of the Kyushu Region (n = 997), which is recognized as a flood-prone area in Japan. The results showed that participants tended to consider a warning as a hit when the river water reached a hazardous water level or when an overflow or levee breach occurred. Furthermore, when a false alarm occurred, negative emotions such as sadness and anger tended to decrease, whereas positive emotions such as being pleased and at ease tended to increase. We found a non-significant relationship between FAR and pFAR, which was maintained regardless of the participants’ hit definitions. However, we found that pFAR had a significantly negative effect on the probability of evacuation, and this negative effect was weaker among those who experienced positive emotions toward false alarms. These findings suggest that effective EWS require not only improvements in scientific warning accuracy but also risk communication strategies that consider emotional responses to false alarms (e.g., encouraging the public to view false alarms as opportunities for evacuation drills).