中文摘要：

[目的／意义]政务微博是政府处置突发危机的重要信息发布平台，在引导公众舆论、调动社会资源等方面发挥着不可替代的作用，研究政务微博的集群效应有重要意义。[方法／过程]以天津港“8·12”特大火灾爆炸事故为例，以“天津发布”为中心的62个市、区级政务微博组成的微博群为研究对象，采用内容分析法，对爆炸事故中天津政务微博群第一响应情况、传播影响力、议题设置及交互微博议题进行分析。[结果／结论]研究发现地方政务微博在突发危机中第一响应较慢，议题设置缺乏主导，交互意识和策略均有待增强。地方政务微博在应对突发事件中应加强预警，快速响应网络舆情，抢占舆论引导权和话语权；科学设置议题，优化交互策略，促使信息公开与舆论引导有机结合；提高交互意识，发挥集群效应，加强与内部机构、媒体、意见领袖等沟通协调，强化联动协同网络。

英文摘要：

[ Purpose/Significance ] Government microblog has become an important information-releasing platform for government to deal with public emergency, and it plays an irreplaceable role in guiding public opinions and gathering social resources, which reveals the great significance of researching government microblog group. [ Method/Process] Choosing Tianjin Port explosion as the research case and the public mieroblog group containing 62 local government microblogs in municipal level and county level of Tianjin as research objective, this paper applied content analysis method to analyze first response status, spread influence, agenda-setting procedures, and the interactive issues of government microblog during Tianjin Port explosion. ~ Result/Conclusion ] The results demonstrate that local government microb- log presents inefficient response and unscientific agenda-setting during emergency. Mutual concern rate between different government microblogs and the interactive awareness among them are required to be enhanced. Consequently, this paper presents the following recommendations： the first one is to enhance collaboration among different government departments, and thereby improve the communication ca-pability and explanatory power; the second one is to set proper agenda and propose effective interaction strategies in terms of promoting combination between information disclosure and public opinion guidance; and the third one is to improve the communication and negotiation among different departments, medias as well as opinion leaders, in order to construct collaborative network and enhance the effectiveness and efficiency of collaboration.