In the presentation they note that between 1968 and August 2009 there were 143 documented tailings dam failures worldwide. However, the occurrence of these failures appears to be cyclic with time, with peaks in the periods 1976-8, 1984-6, 1990-2, 1998-2000 and 2008-now. They compared these peaks with the cyclicity of the global copper and gold prices. The key part of the presentation is a table that compared the timing of the peaks:
The authors' conclusion is that there is a relationship between the peak in commodities prices and the occurrence of tailings dam failures, with a lag between the two of about two years. I must admit that I am a little unconvinced by the statistics of this analysis (I would like to see a proper regression analysis to see whether this link is statistically valid - and to be fair the authors recognise that this is not a scientifically-rigorous analysis), but the central point is one that is certainly very thought provoking. Increased commodity prices drive increased exploitation. The relationship between the peak in prices an the peak in accidents is ascribed by the authors to:
- The rush to mine quickly means that design and construction standards may be low;
- Rapid turn-over of key staff as new (presumably lucrative) opportunities arise during the boom;
- The boom drives the development of resources in areas that are known to be difficult;
- after the boom there are pressures to cut costs as commodity prices decline;
- The boom drives the use of inappropriate designs imported from other locations;
- There may be a lack of independent review, presumably to avoid the time delays and costs associated with this.
Hat-tip to Jack Caldwell's excellent I think Mining blog for highlighting this paper.