Abstract: [Purpose/Significance] In the context of sudden-onset natural disasters, the dissemination of help-seeking information via social media directly impacts the timeliness of emergency responses. This study examines the characteristics distribution and cascading diffusion paths of such information, aiming to provide a basis for optimizing emergency information management strategies and enhancing effectiveness of emergency management. [Design/Methodology] Firstly, an influencing factor framework is constructed based on the Heuristic-Systematic Model of information processing. Natural language processing techniques such as topic extraction and sentiment analysis are employed to extract and quantify the characteristics of help-seeking information. Secondly, combining the Independent Cascading Model with social network analysis, the scale, depth, and structural virality index of the help-seeking information cascade are quantified. Finally, negative binomial regression and multiple linear regression models are utilized to explore the influencing mechanism of various factors on the cascading spread effect of help-seeking information. [Findings/Conclusion] The study reveals that there exists a phenomenon of attention inequality in social media under crisis communication contexts: a small number of help-seeking messages attract most of the attention, which easily leads to some help-seeking messages being overlooked; meanwhile, the expression of negative emotions facilitates the spread of help-seeking messages, while emotional fluctuations inhibit information spread; furthermore, although structured information is beneficial to information spread, the proportion of structured help-seeking messages in real-world scenarios is generally low. [Originality/Value] By integrating the Heuristic-Systematic Model and the Independent Cascading Model, this study expands the research perspective on the spread of help-seeking information during sudden natural disasters. It is helpful for social media help-seekers to optimize their help-seeking strategies, and provides references for emergency management and public opinion managers to develop more scientific and reasonable emergency management decisions.

Keywords: Online help-seeking information, Sudden natural disasters, Emergency management, Crisis communication, Social media