The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
Just under a month ago, I wrote about the tailings failure at the Siana gold mine in Surigao del Norte, Philippines. Capella Space captured good radar imagery of the site. We now have high quality optical satellite imagery too, captured by BlackSky.
They have kindly provided a montage of three images that show the failure:-
It’s clear from the largest (most recent) of the three images that work is underway to rebuild the wall of the tailings storage facility (TSF), presumably to ensure that the remaining waste cannot mobilise. The failed mass is still mostly in situ, but it does not seem to have moved much since the failure.
Meanwhile, Lindsay Newland Bowker of WMTF has been posting other updates about the Siana failure on to LinkedIn, based on work undertaken with a range of volunteer analysts. Interestingly, WMTF is now classifying this as a very serious failure in thickened tailings.
Perhaps most interestingly, two separate InSAR analyses of the site raises concerns about the stability of the walls of the TSFs at Siana. The particular focus is on TSF2 (it was TSF3 that failed last month), which appears to show ongoing deformation.
InSAR is not a definitive tool for the analysis of stability, but these results should lead to a more detailed analysis of the state of the tailings storage facilities at Siana. WMTF is rightly campaigning that InSAR should be adopted more widely to provide advanced warning of potential instability in tailings facilities, especially at sites where the level of conventional monitoring is inadequate.
Once again, Siana is a great example of the ways in which we can independently gain an understanding of these events. Large investors in mining, and their insurers, really should be drawing upon this work to understand the risks that they are carrying.