Accident investigation and lessons not learned: AcciMap analysis of successive tailings dam collapses in Brazil

Tailings dam collapses, though rare, have significant human, economic and environmental impacts. In this study, we analyze two tailings dam collapses in Mariana and Brumadinho, Brazil, in 2015 and 2019 respectively, with a focus on the investigation of the first accident and the repeatability of its causal factors years later. We present an overview of tailings dams failures, followed by a literature review on these two disasters. We synthesize the findings of these reports and highlight the technical, managerial, and governmental factors which contributed to each accident, through an incremental AcciMap approach. We explore the investigation of the Mariana accident, emphasizing the "lessons not learned" which allowed similar causes to develop in Brumadinho. From these results, we propose three sets of recommendations geared towards enhancing the safety of tailings dams operation, improving the safety culture in the Brazilian regulatory environment, and improving the investigation process for dam accidents to ensure all contributing causes are uncovered and addressed. The key point in this discussion is the restructuring of the chains of accountability within dam accident response through nonpartisan inspection and investigation. We conclude with a discussion of the applications of such recommendations in reducing the risk of collapse at similar facilities.