This article analyzes the communication actions and response strategies adopted by the State Secretariat for the Environment and Sustainable Development, of the State of Minas Gerais (Semad) and by the National Mining Agency (ANM), public bodies that act in the concession and inspection mining activity in the State and Brazil, during the crises caused by the failure of the ore tailings dams in Mariana (2015) and Brumadinho (2019), operated by the mining companies Samarco and Vale, respectively. From the content and discourse analysis of a set of 357 notes issued to the media, notices, bulletins and videos published on their websites and online social networks, it was concluded that state bodies failed to provide local communities with information that could be substantial in providing security for their lives, property and the environment in which they live. It was found that there was: i) the production and dissemination of information, but without attention to message recipients and marked by unidirectional, top-down, non-dialogical communication; ii) intergovernmental communication, when state organizations speak within the very government entities to which they are linked or hierarchically submitted; iii) low presence and use of social media; iv) low interactivity with users on online social networks; and, v) non-existent interactivity channels, for direct communication with local communities. [ABSTRACT FROM AUTHOR]