Satellites throw light on mine landslide


In the early morning of January 23, the northern wall of an open-pit copper mine collapsed in Spain.

Fortunately, no lives were lost, but the land slippage led owner First Quantum Minerals to suspend operations for a week.

When incidents occur, like this one at Cobre Las Cruces (CLC), the copper market is eager for information.

However, there can be a delay in knowing something even happened. Then there are important questions about the extent of damage that may go unanswered.

Satellite imagery can close this information gap by providing near real-time updates on market-moving events. It’s similar to having eyes on the ground.

That’s exactly what we did after the landslide occurred January 23 at Cobre Las Cruces. The mine is located in Gerena, approximately 20 km north of Seville.

We provided an update January 25 using imagery taken “before” and “after” to assess the situation on the ground.

It shows the central portion of the CLC mine pre- and post-collapse, which caused land slippage that destroyed most of the infrastructure located northwest of the open pit. The pit flooded and roads were destroyed.

The imagery below come from synthetic aperture radar (SAR). SAR is valuable because it works in any weather, day or night.

Take a moment and focus on the detail inside the red line.

The pre-slippage image shows the east/north side of the pit as a crescent-shaped area of dark pixels. That’s because the side of the pit is very steep. The radar signals are basically lost.

Pre Slippage Fixed-03.png

Credit: Copernicus Sentinel data 2019, processed by ESA
Image date: Jan. 22, 2019

After the land slippage, the signals bounce back to the radar because the geometry has changed. What had been a vertical drop is now a slope of rock and dirt.

An area of white pixels has replaced black pixels representing the same section of the CLC mine’s east/north wall.

Credit: Copernicus Sentinel data 2019, processed by ESA
Image date: Jan. 23, 2019

The difference might appear subtle, but to anyone accustomed to SAR images, like our team of radar engineers, the contrast between “before” and “after” is revealing. A major event like a landslide clearly took place.

Our expertise in processing and analyzing SAR imagery opens other avenues for exploration.

For example, it would be possible to detect subtle changes in positions and elevations to analyze the stress on the surrounding soil.

Technically, using SAR, this type of landslide might have been predicted if the area was being monitoring ahead of time. In addition, satellite imagery can be leveraged to assist and monitor recovery efforts by identifying safe paths into and out of the region.

Besides SAR, another type of satellite imagery we can utilize is optical.

The optical images below were also taken “before” and “after” the land slippage at the CLC mine.

The destruction is clearly visible, but remember that wouldn’t be the case on a cloudy day. Or if the image needed to be collected at night.

In some parts of the world, like the tropics or parts of China, it could take weeks before the conditions are ideal enough for an optical image to have any value.

pre slippage 01.png

Credit: PlanetScope
Image date: Jan. 14, 2019

post slippage 01.png

Credit: PlanetScope
Image date: Jan. 25, 2019

First Quantum said February 1 that copper production had resumed using stockpiles of lower-grade ore.

Another area of the mine (Phase 6) will be mined once regulatory approvals are granted. That area was unaffected by the incident.

First Quantum lowered its estimate of 2019 copper production by 25,000 tons to 45,000 tons.

The company also lowered its 2020 estimate by 25,000 tons because certain high-grade ore is no longer expected to be used.

First Quantum mines the ore in an open pit by blasting and drilling the rock. Copper is extracted from the ore and processed at the plant into copper cathodes.

The final product weighs approximately 50 kg each and meets the specifications of the London Metal Exchange (LME) contract.

LME copper prices rose by 3.7% to $6,146 a ton ($2.78/lb) from January 22 until January 31.

First Quantum said the 2018 costs at Cobre Las Cruces were $0.90 per pound versus an average spot price of $2.82/lb.

The costs at CLC mine ranked as the second least expensive among the eight places First Quantum has active operations. The other sites are in Panama, Zambia, Spain, Mauritania, Finland and Turkey.

The global nature of the mining industry makes it an ideal candidate for satellite imagery to be utilized.

And not only is monitoring important for the commodity business, but for a broader segment given the human and environmental costs associated with any disaster.

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