Tailings dam collapse at Feijão iron mine in Brazil

Sentinel-1 CSAR IW acquired on 04 November 2015 at 08:21:34 UTC
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Sentinel-2 MSI acquired on 22 January 2019 at 13:12:41 UTC
Sentinel-2 MSI acquired on 27 January 2019 at 13:12:49 UTC
Sentinel-1 CSAR IW acquired on 29 January 2019 at 08:21:09 UTC
Author(s): Sentinel Vision team, VisioTerra, France - svp@visioterra.fr
Keyword(s): Geohazard, landslide, emergency, anthropic disaster, natural resources, geology, mountains, river pollution, toxic
Fig. 1 - S2 (22.01.2019) - 12,8,4 colour composite - Brumadinho (Minas Gerais state, Brazil) before the disaster.
Fig. 2 - S2 (27.01.2019) - 12,8,4 colour composite - Brumadinho after the tailings dam collapse at Feijão mine.
Another tailings dam collapsed in the mineral-rich state of Minas Gerais, Brazil. Feijão iron mine "is the main economic activity in Brumadinho and now the cause of this unprecedented tragedy that will mark generations to come. The Paraopeba river that cuts through the town has been tinted by iron ore residue and now smells of dead fish.", BBC reported. According to the Brazilian news network Globo, 121 people have died, 226 are still missing. And "since the 26th January, there are no survivors found." Their videos of the disaster show the magnitude of the event.
Fig. 3 - S1 (12.12.2018, 24.12.2018, 05.01.2019 & 17.01.2019) - vv(mean before),vh(mean before),vv(mean before) colour composite.
The 87-m high tailing dam had been built in 1976, it could hold 12.7 millions cubic meters according to its owner, Vale, the first mining company in Brazil. Among all its dams, Vale had assessed the risk of failure of this tailing dam in the lowest category.
Fig. 4 - S1 (29.01.2019) - vv,vh,vv colour composite - First descending radar acquisition after the disaster.
The Brazilian Report informed that: "In response to the mounting pressure, Vale has announced it will decommission all of its tailings dams which use the same structure as those in Brumadinho and Mariana, highlighted by experts as being a potential cause for the two catastrophic failures over the past three years. The dam in Brumadinho was raised using what is called an “upstream” design, where embankments, made from tailings, are piled on top of one another, creating a staircase effect and moving the dam upstream. This particular format is regarded as being the least safe and most cost-effective method of raising dams."
Indicative cross section of the tailings dam that collapsed to generate the Brumadinho disaster - Source: Pirete and Gomes (2013).
Fig. 5 - S1 (17.01.2019) - vv,vh,vv colour composite - Latest descending radar acquisition before the failure.
The image above highlights the difference between a single acquisition and the mean of several images acquired with the same viewing geometry. The latter processing is computed on the fly. By reducing the speckle, finer details are revealed and photo interpretation is made easier.

The Brazilian Report further explains "Vale administers a further ten upstream dams, all of which are situated in Minas Gerais, and are currently inactive (no further tailings are being deposited there). At the same time as the company has pledged to get rid of its own upstream dams, Minas Gerais courts have ordered that no licenses can be granted or renewed for such structures in the state."

"Vale takes the tailings drained from its dams to manufacture a product called Brazilian Blend Fines (BRBF), a mixture of different types of iron ores which has quickly become one of the company’s most important products. Even before the Brumadinho disaster, BRBF was set to be Vale’s highest volume product in 2019. The sale of BRBF is now particularly attractive, due to the high price of iron ore around the world. While it may appear to be a sacrificial measure in response to the dozens of lives lost in Brumadinho, Vale’s decision to decommission these upstream mines may actually be quite profitable. "
Fig. 6 - vv(mean before),vv(after),vv(mean before) colour composite - Multidate VV polarisation composite.
Fig.6 and Fig.7 show the mean of the latest four Sentinel-1 ascending images acquired before the disaster in the blue and red channel. The green channel shows the first post-disaster Sentinel-1 ascending acquisition. Greyish tones indicate little change before and after while saturated green or magenta colours show important change in the land backscattering. The impact of the mud flood is well visible: the reservoir emptied, buildings and bare soil were covered, some forested areas were destroyed, the river network was swollen by the volume of mud and it banks were flooded as well.

The Brazilian Report concludes : "Much of the outrage surrounding the Brumadinho catastrophe concerns the fact that the collapsed tailings dam had all of its environmental permits and licenses up to date at the time of the incident. The fact that these safety concerns were “unnoticed,” casts a shadow over the inspection process of this and the rest of Brazil’s dams. In truth, big Brazilian mining companies have been given an easy ride by environmental regulators, with Vale even receiving some slack from state legislators just days after the collapse in Mariana, in 2015."
Fig. 7 - vh(mean before),vh(after),vh(mean before) colour composite - Multidate VH polarisation composite.
Fig. 8 - S1 (04.11.2015) - vv,vh,vv colour composite - Bento Rodrigues in november 2015 before it was hit by a dam failure.
Only 3 years before, the company Samarco, which is jointly owned by the Anglo-Australian company BHP Billiton and, already, Brazil’s Vale, was responsible for another disaster which reached a lower toll in humain lives but likely had a worse environmental impact. The Bento Rodrigues dam disaster, happened on 5 November 2015, when an iron ore tailings dam in Mariana (67 kilometers south-east of Belo Horizonte, in the state of Minas Gerais, Brazil) suffered a catastrophic failure, resulting in flooding that destroyed the village of Bento Rodrigues. The failure of the Bento Rodrigues dam has been described as the worst environmental disaster in Brazil's history.
Fig. 9 - S1 (16.11.2015) - vv,vh,vv colour composite - Bento Rodrigues devastated after a similar tailings dam collapsed.
Around 33 million cubic meters of iron waste flowed into the Doce River, causing toxic brown mudflows to pollute the river and beaches near the mouth when they reached the Atlantic coast 17 days later. The disaster sparked a humanitarian crisis as hundreds were displaced and cities along the Doce River suffered water shortages.

A United Nations report counts "Nineteen people were killed", "the tailing slurry traveled 620 km downriver, eventually reaching the Atlantic Ocean", "entire fish populations – at least 11 tons – were killed immediately when the slurry buried them or clogged their gills" and "the force of the mudflow destroyed 1 469 hectares of riparian forest". The mudflow "contained high levels of toxic heavy metals and other toxic chemicals" such as arsenic.

Landsat -7 & -8 showing the pollution extent of the Bento Rodrigues tailings dam disaster, 500 km further at the mouth of Doce River - Source: VtWeb
Fig. 10 - S2 (26.12.2015) - 4,3,2 natural colour - The huge mudflow that covered the valley shows on this early Sentinel-2 image.
The Guardian then reported: "In Rio de Janeiro, the headquarters of Vale have had regular protests since the accident on 5 November. But the government has also come in from strong criticism for the laxity of the dams’ inspection regime and Brazil’s weak environmental legislation." "So far, Samarco has agreed to pay R$1bn (US$270m) in clean-up costs and compensation, along with a further R$250m in fines. But critics argue this is nowhere near the cost of the damage. 'The economic value of the fines that have been applied so far are comical,' Mario Moscatelli, a Rio-based ecologist, said. 'They merely provide an incentive for big companies to continue polluting Brazil because it’s worth it.'"

All the more since Globo has signaled that: "Companies involved in environmental disasters have paid only 3.4% of the fines they received."
Fig. 11 - S2 (26.12.2015) - 12,8,4 colour composite - Sediments also filled the floor and banks of Doce River.
This time, it could be more painful for Vale, Agence France Presse wrote: "Brazilian judicial authorities announced they had frozen $3 billion of Vale's assets, saying real estate and vehicles would be seized if the company could not come up with the full amount. The company also has been hit with fines by the federal and state government totaling some $92.5 million." Furthermore, at the end of January 28, Vale's stock price had fallen by 24%. Vale's debt was downgraded to a rating of BBB- by Fitch Ratings. Vale S.A. lost more than R$70 billion (approximately US$19 billion) in market value.