Satellite imagery collected in the months leading up to the catastrophic Samarco mine disaster on November 5 in Minas Gerais, Brazil reveal a substantial increase in the amount of water and mine waste being stored behind the now failed Fundão Dam. Images taken by the satellite Earth-imaging company Planet Labs two months before the dam collapse show that Samarco, co-owned by BHP Billiton and Vale SA, were acting on their plans to raise the height of the dam. Compared to 2013 Astrium imagery in Google Earth, additional structures appear at the top of the dam, trees have been cleared and roads have been cut to accommodate the heightened level of waste in the reportedly 55 million cubic meter impoundment:

On the left side of the image you can see that by September 2015 the fluid level had risen substantially since May 2013, filling valleys upstream of the dam. In the center, you can see the growth of the dam as new contours are added, presumably to raise the crest of the dam. According to our calculations, between May 2013 and September 2015 the surface area of the impoundment increased by approximately 100 acres (406,000 sq. meters).

Though the comparison is not nearly so stark, here is another image collected by Planet Labs on October 2, side-by-side with the same September 25 image seen above. The images were collected at different times of day, so features that were in the shadows on one image will be visible in the other:

Mining and Civil Engineers – See anything notable about developments at the Fundão Dam? Leave a comment below.