On March 9th, 2018, a tailings dam has failed at Cadia, a large open pit gold mine in Australia. Dave Petley for the AGU landslide blog collected aerial and satellite (Planet) images of the dam before and after the event. The Newcrest mining company also published a report on the failure.
The embankment slump is also clearly visible in Sentinel-2 imagery. Here I used a near-infrared compositing because it enhances the contrast between the vegetation (bright in the near-infrared) and the water (dark in the near-infrared).
When I did this animation, I was not expecting to see this progressive color change in the northern tailings -- as if someone was methodically painting the landscape?
Tim Barrows and Dave Petley kindly helped me figure out that this is a crusting agent spread by an aircraft. This type of product is used to prevent dust lift off.
The aircraft is visible in this video by Jeremy Buckingham.
According to him, the Newcrest company is spreading this crusting agent because the tailings deposit became very dry after the dam failure. Jeremy is a New South Wales Member of Parliament, with the portfolio interests of Mining and Gas extraction and affiliated to the Australian Greens. I trust him when he says that he's smarter than he looks. In fact, his explanation sounds better than my land art hypothesis...