The tailings dam failure of 5 November 2015 in SE Brazil and its preceding seismic sequence

• Published in: Geophysical research letters 2016-05, Vol.43 (10), p.4929-4936
• Main Authors: Agurto‐Detzel, H., Bianchi, M., Assumpção, M., Schimmel, M., Collaço, B., Ciardelli, C., Barbosa, J. R., Calhau, J.
• Format: Article
• Language: English
• Subjects: Accidents; Brazil; Collapse; Dam failure; Dam safety; Dams; Earthquakes; Failure; Floods; Legislation; Liquefaction; Mine tailings; Mine wastes; Mining accidents & safety; Mudflows; Samarco; Seismic activity; seismic hazard; seismic noise; Seismic phenomena; Seismography; Sequencing; Shaking; Soil; Soils; Tailings; tailings dam; Turbulence
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2016GL069257

The collapse of a mine tailings dam and subsequent flood in SE Brazil on 5 November 2015 was preceded by a small‐magnitude seismic sequence. In this report, we explore the spatiotemporal associations between the seismic events and the accident and discuss their possible connection. We also analyze the signals generated by the turbulent mudflow, as recorded by the Brazilian Seismographic Network (RSBR). In light of our observations, we propose as possible contributing factor for the dam collapse either ground shaking and/or soil liquefaction triggered by the earthquakes. The possibility of such a small‐magnitude earthquake contributing to the collapse of a tailings dam raises important concerns regarding safety and related legislation of dams in Brazil and the world. Key Points We detected and characterized a small‐magnitude earthquake sequence preceding the collapse of a tailings dam in Southeast Brazil Seismic signals from the mudflow were recorded at regional stations for 25 min and confirmed by their polarization The tight spatiotemporal relation between quakes and accident makes the contribution of ground shaking to the dam rupture highly probable