PurposeDisaster narratives constitute a crucial and unique element in disaster understanding, recovery and communication. Along with facing various severe disasters, China’s dominant official disaster narratives have played an indispensable role in promoting post-disaster social solidarity. However, the consequences of “weak” official disaster narratives remain unknown.Design/methodology/approachIn 2023, during a riverine flood in northern China’s Z City, diversified grassroots disaster narratives emerged, “filling the void” when the official narratives were comparatively “weak”. This paper uses this riverine flood in Z City as an uncommon case to analyze the official-grassroots disaster narrative interaction. During fieldwork, first-hand and second-hand data from in-depth interviews, on-site visits and public information were collected.FindingsBased on fieldwork, this paper first introduced the “weak” official disaster narratives in Z City. Second, this paper organized and classified these grassroots disaster narratives into three interconnected stages: the flood’s causes, government and social responses, and recovery. In “filling the void,” “sacrifice” and “betrayed” sensemaking are detected and functions of these diversified grassroots disaster narratives become clear.Originality/valueOfficial and grassroots disaster narratives are not simply competing, but complementary. As a unique soft lens to interpret disasters, this paper further discussed grassroots disaster narratives’ underlying connotations and potential impacts on social resilience building. Also, this paper provides insights into the disaster narrative dynamics, especially in China’s political and cultural context.