Exploring dynamic public trust in mega infrastructure projects during online public opinion crises of extreme climate emergencies: Users' behaviors, trust dimensions, and effectiveness of strategies.

The vulnerability of mega infrastructure projects (MIPs) has generated online public opinion crises, leading to public trust damage. However, few studies focused on the online dynamic trust of MIPs in such crises from the perspective of multiple users. Based on situational crisis communication theory, this study aims to explore the dynamic public trust in MIPs during online public opinion crises of extreme climate emergencies. The extreme heavy rainstorm event in Zhengzhou City, China, was selected as the case. Content analysis, the curve fitting method, and sentiment analysis were conducted to process the collected data from multiple users. The results indicated that the opinions of trust damage were set by "media practitioners" and led by "elites," whereas the opinions of trust repair were directed by "elites," led by "media practitioners," and defended by "individuals." Besides, trust dimensions would change over time; integrity-based and competence-based trust diffused alternatively. "Diminish," "deny," and "rebuild" strategies were proved to be the most effective strategies in integrity-based, competence-based, and competence and integrity-based trust repair, respectively. The findings can contribute to the authorities monitoring online public opinions in extreme climate emergencies and repairing trustworthy images.