3 February 2020
Gongo Soco mine: Planet Labs images of the movement of the rock wall
Back in October 2019 I posted about the very large-scale deformation occurring in the rock wall above the Sol Superior tailings dam at the Gongo Soco mine in Brazil (location: -19.957, -43.599). This closed gold and iron ore mine, operated in recent years by Vale, has had a number of stability issues in recent years, of which the deformation of the rock wall is the most serious.
This part of Brazil suffered extremely heavy rainfall in the second half of January, inducing landslides and flooding that claimed a large number of lives. Last week Vale raised the alert level at Gongo Soco after the rainfall eroded the structure of the Sul Inferior dam, although to date no failure has occurred. Meanwhile the alert level for the Sul Superior dam remains at “Level 3”, which indicates that failure of the structure is “imminent or underway”.
This is an image that Planet Labs captured on yesterday, 2 February 2020, again using the PlanetScope instrument:-
It is clear that in the three month period between the two images the slope has evolved considerably. Most notable is the growth of the fresh rock surface at the crown of the landslide (immediately below the small cloud in the image above). This appears to be over 50 m long from top to bottom and over 300 m long across the slope. The implication is that the entire mass has slipped considerably. The fractures running from top to bottom on the slope are now better developed, indicating that the mass continues to deform.
The slope is being monitored 24 hours a day by Vale’s Geotechnical Monitoring Centre. Unfortunately, as far as I can tell, this data is not online.
Planet Team (2019). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/