The collapse of a deadly reservoir – causing one of the worst environmental disasters in Brazil – could have been predicted

The top left and bottom right are Google Earth satellite images of the Brumadinho wastewater dam taken before and after the collapse on January 25, 2019. Top right and bottom left, shows warm movement along the dam (red and yellow). find that collapse is predictable. Credit: Google Earth

According to a new study from the University of Nottingham and the University of Durham, one of Brazil’s worst environmental disasters – the collapse of a dam that killed more than 200 people – could be expected with proper monitoring technology.

The high-profile disaster occurred on January 25, 2019, at a landfill near the Córrego do Feijão iron ore mine near the town of Brumadinho in the southeastern Brazilian state of Minas Gerais.

When the dam collapsed, a flood of silt caused the surrounding lands to be covered; take lives, destroy homes and livelihoods, and pollute rivers with toxic substances.

Brumadinho satellite image

Satellite image of Brumadino before and after the dam collapsed. Credit: Images of NASA Earth Observatory by Lauren Dauphin using Landsat data from the US Geological Survey

The tailings dam, owned by Brazil’s largest mining company, Vale, has been used to store waste at the mine for more than 40 years. It is not uncommon for such items to move when more material is added and compacted and changed, and there should be no accelerated movement; is a warning that failure will occur. Brumadinho was Vale’s second mine, which collapsed in recent years, and was one of many reported failures around the world.

Professor Stephen Grebby, a lead assistant professor at the University of Nottingham’s Institute of Geography, says concerns about the sustainability of this type of dam are growing and that more advanced monitoring is needed.

Specialist in mapping the Earth’s surface from space Dr. “Most mining companies now rely on surface sensors to monitor the stability of dams,” Grebby said. However, they generally offer insufficient coverage of measurements throughout the paragraph, which may make it difficult to detect movement or other signs of concern. ”

Stephen Grebby

Dr. Stephen Grebby is a lead research author at the Nottingham Institute of Geography at the University of Nottingham. Credit: University of Nottingham

Applying InSAR (satellite radar imaging) to check for dams and small ground movements in the vicinity is not the current standard practice, and Dr. That’s something Grebby wants to see change.

He partnered with Terra Motion Ltd, a split company at Durham University and the University of Nottingham, to determine if the failure at Brumadinho could have been predicted.

The University of Nottingham and Terra Motion used an advanced InSAR technique called the Intermediate Small Beginning Subgroup (ISBAS), which can help overcome the limitations they face when using some of the more traditional InSAR techniques in vegetated areas. Another benefit of this technology over ground sensors is that it looks from top to bottom and provides a fuller view of ground movements at the millimeter level. accuracy.

Andy Sowter

Dr. Andy Sowter, CTO Credit of Terra Motion Ltd.: Terra Motion

Dr. Grebby adds: “Our ISBAS InSAR results show that different parts of the dam are moving at different speeds, and some of them are accelerating suddenly in the two months before the collapse. Although the dam was tracked by the mining company using standard techniques without any explicit warning, our initial motion analysis shows the time of the collapse. was predictable.

“If the ISBAS were monitored regularly using the InSAR technique, the failure could have been predicted a week after it occurred. Critically, this prognosis could have been possible about 40 days before the collapse, and time is given for a warning that the dam will become unstable. This could lead to deeper monitoring or other mitigation measures to prevent catastrophic human losses and environmental disasters. ”

Full findings published in a recent article ‘Advanced Analysis of Satellite Data Reveals Predictions of Earth Deformation at the Brumadinho Tailings Dam In the journal Nature Contact Earth & Environment.

Professor David Toll, co-director of the Institute for Danger, Risk and Sustainability at Durham University, said: “Determining the acceleration of earthquakes during pre-failure aging has helped confirm the expected failure mechanism. The collapse of the waste dam can be explained by the reduced absorption in the waste, which affects the internal strains, which can lead to static liquefaction in the fractured materials. ”

Professor John Gluyas, Executive Director of the Durham Energy Institute at the University of Durham, said, “The new use of InSAR satellite data to monitor dam sustainability is a real breakthrough because it means you don’t have to build a ground around and around the earth. dam to watch it. Thus, monitoring is no longer in the hands of the operating company alone. ”

KTO of Terra Motion Limited and the inventor of ISBAS advanced InSAR equipment, Dr. Andrew Sowter said, “This would not have been possible without the free and rich global satellite data from the Sentinel-1 mission. near future. In addition to the innovative approach described in this article and our unique InSAR products, this low-cost remote waste monitoring system is available locally, regionally and even nationally around the world. ”

Researchers are now trying to develop the technology as a program that can be offered to the mining industry looking for a reliable, early warning system to predict the risk of imminent collapse in mining depots. Dr. combined with sensors on the ground. Grebby sees advanced InSAR techniques as a valuable addition to the tracking toolbox to free up and protect lives.

Reference: “Analysis of Advanced Satellite Data Reveals Predictors of Earth Deformation of Brumadinho Tailings Dam Dam” Stephen Grebby, Andrew Sowter, John Gluyas, David Toll, David Gee, Ahmed Athab and Renoy Girindran, January 4, 2021, Contact Earth & Environment.
DOI: 10.1038 / s43247-020-00079-2

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