Biggest Landslides

Mar - 15 2017 | no comments | By

Is the Bingham Canyon copper mine landslide the most expensive single mass movement in history?

Mar - 15 2017 | no comments | By

Is the Bingham Canyon copper mine landslide the most expensive single mass movement in history?

Further news is emerging about the landslide at Bingham Canyon copper mine last week.  The transparency of all involved is impressive to behold, and is a remarkable contrast to the much more costly in human terms landslide at the Jiama mine in Tibet.  I thoroughly recommend that you visit the Kennecott Utah Copper flickr site, which has some wonderful images of the landslide.  I cannot post them here, but do take a look.

In landslide terms this event was a major success, with one substantial caveat, in that detailed monitoring allowed the event to be predicted, which meant that the mining operations were stopped and the mine was evacuated prior to the event.  The mine was using slope deformation radar systems provided by the Italian Company IDS, which can detect movement in the walls of the mine.  Interpretation of the movement patterns can be used to forecast and even predict a failure event – indeed this is an area that our research group at Durham has worked upon in some depth.  The caveat of course is that the size and travel distance of the landslide does not seem to have been anticipated.  Indeed Rio Tinto released a market report that said:

The size of the slide was significant,” the company said in an emailed statement. “We don’t have information yet regarding the magnitude or impact. We do know that the flow into the pit extended beyond the scenarios we forecasted, having a greater impact on equipment.

I suspect that we need to undertake more research on the ways that we can extract this sort of information from these datasets – my colleagues and I have also been working on this.  It would be fascinating to back analyse the dataset from this event to see if we can develop better techniques.  I suspect that if we transfer the techniques we have been developing in New Zealand and Italy to this setting and data type we might be able do this better.

Meanwhile, the implications of this event are becoming apparent.  Locally the mine is continuing to produce copper through stockpiled resources (they are reported to have 20 days worth of resources), but the Wall Street Journal is reporting that the mine is asking its workers to take leave.  As the images below show, the landslide has caused the loss of a large part of the wall of the pit, filled the mine floor, destroyed buildings and the haul road, and buried equipment.  Mining cannot be restarted until the haul road is rebuilt (in itself this is not trivial), and the above article suggests that it will take months rather than weeks to restart production.  A key issue will be the stability of the material left on the slipped slope – if further movement occurs then restarting mining will be difficult until it has been stabilized.

The costs of the landslide are interesting.  The mine produces 17% of copper in the US and 1% worldwide.  One estimate has suggested that the landslide might cost Rio Tinto $1 billion, which would I think make it the most expensive landslide of all time.   The Wall Street Journal has an estimate that is hard to read:

Commonwealth Bank said Monday that assuming the Bingham Canyon mine isn’t operational for the rest of the year, the mine likely would report a loss of US$79 million. The bank had previously expected the mine to earn US$701 million this year, about 6% of Rio Tinto’s total earnings.

My interpretation of this is a loss of $770 million, slightly lower but still a huge sum of money. There are also some concerns that the event might cause an increase in global copper prices, but so far this does not seem to have occurred.

I am sure that more information will emerge in the next few days – I will post again if this is the case.

More information on the disastrous mining-induced landslide in Tibet a fortnight ago

Mar - 15 2017 | no comments | By

Questions continue to be asked about what I have been calling the Jiama/Gyama Mine landslide in Tibet.  First, it should be noted that this is a misnomer – the event should correctly be called the Tseri Mountain landslide I think, so from here-on in this will be how I refer to it.  Anyway, I thought I’d highlight three sources of information about the landslide that are all very helpful.  Note that all have been compiled independently from my own analysis.

1. An interpretative report about the landslide by Adrian Moon

Adrian Moon, who regularly contributes this blog, has written an analysis of the landslide.  This is a very impressive piece of work.  He has given me permission to make it available, so I have uploaded it onto Slideshare and have embedded it below.  You should be able to read it below.  Adrian also asked me to acknowledge the input of his colleagues Robert Barnett, Professor of Contemporary Tibetan Studies, Columbia University and Yeshi Dorje at the Voice of America Tibetan Service.

2. A formal report about the landslide from the Central Tibetan Administration
There is a very interesting and detailed report about the landslide online from the Central Tibetan Administration.  This is available online.  As well as providing detailed information about the landslide and its background, and highlights the information deficit from the Chinese authorities.
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3. An analysis of the landside dynamics
Kerry Lieth, who is a Post-Doctoral Researcher at TU Munich, has an excellent blog about his research.  He has a post online in which he uses press images to map the landslide.  This is an impressive piece of work.  The upshot is a map of the landslide extent that he has given me permission to reproduce:
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https://sites.google.com/site/kerryleith/home/updates/mappingthegyamajiamaminelandslidefrompressimages

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It is notable that in all three cases the idea that this was an entirely natural “act of god” is challenged.  I concur with this.

Landslide hazards in the aftermath of the Lushan earthquake in Sichuan

Mar - 15 2017 | no comments | By

A number of Chinese media outlets have articles about the threats posed by landslides in the aftermath of the 20th May 2013 Lushan earthquake in Sichuan Province.  It is clear from the imagery (such as the image below) that landslides have represented a very significant component of the costs of this earthquake, although at present it is not clear just how many of the deaths were caused by mass movements.  The next major threat is the upcoming rainy season – just weeks away – which will inevitably cause a combination of further first time failures and debris flows of released materials. Ya’an, the County in which Lushan sits, is nicknamed “the city of rain”.

http://english.cntv.cn/20130422/102663_2.shtml

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In terms of costs, Xinhua are reporting 196 fatalities, 21 people missing and 13,484 injured.  The level of damage is very high – 86,300 buildings have collapsed in the quake and about 430,000 houses have been seriously damaged.

Eastday China reports that a team of 400 geohazards specialists are working to identify hazards, and are developing warning and evacuation plans.  Emphasis is rightly being placed on the emergency camps, which are often extremely vulnerable.  Meanwhile CRI English has an interesting report about landslides that have been deposited into river channels.  Whilst these are not valley blocking at present, the loss of flow capacity may allow a lake to develop during the high flow period.  Clearly this is unacceptably dangerous.  The army are undertaking controlled blasting to clear the blockage.

Landslides and large dams – there may be trouble ahead…

Mar - 15 2017 | no comments | By

Landslides and large dams – there may be trouble ahead…

Yesterday I posted for the second time on the extraordinary landslide problem that has developed at the Laxiwa HEP station in China.  The wider question that goes with this is the degree to which this is an isolated problem, or could it be that this is an indication of a larger issue?  Later this year there is a conference in Italy to mark the 50th anniversary of the Vajont landslide disaster, at which I am presenting a keynote lecture.  The paper that I have written focuses on an analysis of landslides associated with large dams over the last ten years.  The paper is out in October and I don’t pre-publish my work.  However, I thought it would be interesting in the context of Laxiwa to show two maps.  The first is the global distribution of large dams – this is from the UN GrandD database, which provides information of large dams worldwide, mapped onto a global digital elevation model using ArcMap:

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So each red dot here is a large dam (defined as having a storage capacity of greater than 0.1 cubic kilometres).  The interesting thing here is the paucity of large dams in and around the Himalayan chain (and indeed the Andes).  As I have shown before, the Himalayas are really the global epicentre for landslide activity, so this is the environment that requires the highest level of care with respect to landslide problems.  The map below homes in on the Himalayas, again with a DEM as the backdrop:

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You will see that there are two types of symbol shown here.  The circles with dots in the centre are locations in which my database indicates there have been fatality-inducing landslides associated with large dams in the last ten years.  These are mostly landslides at dam construction sites or landslides that have impacted the camps housing employees associated with dam construction or operation.  There are a surprising number of landslides given the numbers of dams in this part of the world.  This suggests to me that we are not managing landslides properly in this part of the world.  The real worry lies in the other symbols – the circles with crosses.  These are large dams that are proposed, planned or under construction in this area, compiled from a variety of sources but drawing heaving on the International Rivers datasets.  Not all of these will be constructed, but the number of new dams in this region is extraordinary, especially in the east of the region.

The threat is clear – the recorded landslides shown above and the Laxiwa problem clearly indicate that there is a landslide problem associated with these structures.  Unless we improve the quality of landslide detection and mitigation, these problems are going to get much worse as these dams are built.

There hasn’t been a repeat of the Vajont disaster in the intervening 50 years, mostly through prudent management of the hazard and perhaps a sprinkling of good fortune.  My sense is that we are pushing our luck to the limit with the planned dams in and around the Himalayan Arc.  The question as to whether these dams should be built at all is important but beyond the scope of this blog. We are thankful for all of the engineers and plumbers who have been hard at work to establish these plans. However, the potential landslide problems in these areas are acute and will require a much higher level of management than appears to be occurring at present.

Another landslide on a reservoir flank – Yesa in Spain

Mar - 15 2017 | no comments | By

In the last few days I have posted a couple of times about a landslide on the banks of the reservoir from the Laxiwa Dam in China.  It hs been brought to my attention that there is another interesting, but this time in Europe, at Yesa in Spain.  The dam, which is located at 42.615N, 1.183E, has an interesting history.  A concrete dam was constructed some years ago, with impoundment being undertaken in 1959.  However, in recent years a new, much larger, dam has been proposed for the site.  There is a description of the proposed project (NB PDF) – the structure is a 117 m high, concrete-faced gravel dam – but this has not yet been built.

It is probably fair to say that the project has not met universal approval, and there are organizations that are actively campaigning against this development. One of the major concerns appears to be the presence of a landslide on the flank of the dam site.  This concern was noticed while they were painting the dam. One of these organizations has a website about the landslide (in Spanish) – Google translate does a good job of rendering it comprehensible for those without Spanish language skills.  Note that the website is clearly presented from a particular viewpoint and I cannot verify the content.

The slope in question is this one – the Google Earth image was taken in 2008:

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The landslide was first identified in the 1930s, when a failure occurred during construction of the original dam.  Reactivations of the movement occurred in 1960 as impoundment occurred, and during heavy rainfall in 1964.  According to the Yesano website, movement was reactivated in November 2003 as the slope was being excavated for the abutment of the proposed larger dam.    The Yesano website has images of the tension cracks, such as this one:

http://www.yesano.com/deslizamientos_Yesa.htm

In July 2007 sliding continued to develop and works were suspended whilst a new investigation was undertaken.  Further movement occurred in April 2008.

More recently, in April 2012, the Yesano website reports that further movement occurred 200 m downstream of the dam:

http://www.yesano.com/deslizamientos_Yesa.htm

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In February 2013 the situation deteriorated during heavy rainfall, and considerable additional movement occurred, such that the authorities announced works to stabilise this flank of the abutment.  The Yesano website notes that 60 houses on the landslide were evacuated.  They won’t know until next month when they can return to their homes.

They have an image showing their interpretation of outline of the landslide as it is now:

http://www.yesano.com/deslizamientos_Yesa.htm

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The authorities report that movement rates are currently low (about 1.5 mm pr month), but a large landslide on the flanks of a concrete gravity dam must be a source of real concern.