Continued questions about the role of the quarry in the Tumbi Quarry landslide

By Prof Dave Petley

Wilson Professor of Hazard and Risk in the Department of Geography at Durham University in the United Kingdom. 

(Originally Posted on the Landslide Blog)

Interestingly, over the last few days there appears to have been increased interest in the role of the quarry in the Tumbi Quarry landslide.  Regular readers will remember that the National Disaster Center report indicated that the failure developed as subsidence close to the quarry.  Triggering of the landslide was associated with heavy rainfall, with no evidence to support this trigger, and no other mention was made of the quarry, even though it is clear from the images that a section of it was removed by the landslide.  In an earlier post I questioned both the evidence for rainfall / high groundwater as the trigger and the lack of consideration of the role that the trigger might have played.

Two recent statements have been reported by those associated with the disaster.  First, in a Radio Australia interview, Martin Path, who is the Principal Disaster Coordinator for the  Southern Highlands province in  Papua New Guinea, has given a rather different perspective to that from the official report(LAM is Sen Lam, the interviewer):

LAM: And Martin, at the time of the disaster, the landslide was blamed on blasting at nearby quarries, near the Exxon-Mobil LNG project in the Southern Highlands. Is a clearer picture emerging, of what happened, that early Tuesday morning? Are you getting a clearer picture now?

PATH: Not as yet. We have yet to conduct, er, we are conducting some portion of the independent investigation that the National … Council has endorsed. We believe that an independent investigation unit has been assigned, and we believe that this group would be up here over the weekend. But we also have the geo-hazard technical team on the ground now, since Day One. So they’re still providing the information, so with regards to the quarry that was established some years back, we have yet to establish the actual cause, what actually caused this slide.

There is a strange confusion here – “We have yet to conduct, er, we are conducting some portion of the independent investigation…We believe that an independent investigation unit has been assigned, and we believe that this group would be up here over the weekend.”  It is hard to interpret what is going on from that.

Second, my earlier posts have been picked up by the PNG Industry News website, who then have some comments from an ExxonMobil spokesperson:

An ExxonMobil spokesperson previously told PNGIndustryNews.net that PNG LNG contractors did not conduct any blasting at the Tumbi quarry.

She said a project contractor completed work at the Tumbi quarry in August, 2011.

“There was no need for [PNG LNG-related] blasting at this quarry,” she said.

“The Tumbi quarry has been operating for over two decades.”

There are two issues here.  First, the spokesperson notes that there had been no blasting at the quarry, which is in contradiction to the reports from local people.  I have no way of verifying this either way.  Second, she suggests that work associated with the LNG project ceased six or so months ago.  The unstated implication is that this means that the Exxon-Mobile work was not responsible for the collapse.

However, unfortunately slope behaviour is not as simple as that.  Whilst slope collapses can occur spontaneously during quarrying, there is often a time gap between the processes that lead to failure, and the failure itself occurring.  This is a mechanism known as progressive failure, which was first described in the 1960s.  There are two elements to this:

1. It may well be that the quarrying operations occurred when groundwater levels were low, or indeed that the quarrying caused an initial drawdown (release) of groundwater.  In such circumstances, the groundwater recovers the stability of the slope can reduce, allowing a failure to develop.  Seco

2. Failure of the slope occurs when a shear surface is fully formed that allows the landslide to detach from the surrounding rock.  This is not a spontaneous process, but requires the formation and growth of planes of weakness.  Such a process can take weeks or even years.  I have written several papers on this very process, such as this (click on the title to download the paper):

Petley, D.N., Higuchi, T., Petley, D.J., Bulmer, M.H., and Carey, J.  2005. The development of progressive landslide failure in cohesive materials.  Geology, 33, 3, 201-204

It can be the case that cutting a slope in a process such as quarrying initiates the progressive failure mechanism, and allows the slope to collapse some time later.

None of this inevitably means that the quarry was the cause of the landslide.  It may have been the direct cause, it may have been one of several causes, or it may be irrelevant.  However, understanding its role is critical.  Once again I would emphasise that this can only be uncovered with a proper forensic investigation by a team who understand the complexity of this type of landslide.  This is not a trivial task, and will involve detailed field mapping; structural measurements; examining aerial and ground images before and after the landslide; examining the quarry design and operation; looking at rainfall records; etc. The methodology for such an investigation is well-established, but undertaking it requires very specialised skills.  Usually this will require an international team.

The loss of a significant number of lives really demands that this landslide is investigated properly.  I do hope that this process is now underway.

Papua New Guinea or Papua New Palmer

Only in the Financial media could you find such frank discussion of PNG's natural resources. Owned by foreigners, divided up among foreigners, for the benefit of foreigners. The family silver has been sold.  


Palmer mulls Exxon deal


Australian Financial Review, 6 February 2012

Mining billionaire Clive Palmer is considering an offer from ExxonMobil to secure rights to explore his expansive gas deposits in Papua New Guinea.

Mr Palmer said Exxon first approached him in 2010 and he held further discussions with the global oil giant again late last year.

PNG-based oil and gas company Chinampa Exploration, a subsidiary of Mr Palmer's Mineralogy, has offshore exploration licences at the northern end of the Gulf of Papua, west of the capital of Port Moresby.

Mr Palmer told The Australian Financial Review that Exxon had proposed "farm-out" arrangements whereby the major would fund exploration work to potentially tap into the area's gas deposits in return for a stake in the venture.

Chinampa holds oil and gas exploration licences covering more than 43,000 square kilometres. The company is in the very early stages of exploration and needs significant funding to help with high exploration costs.

Mr Palmer said he had spent $40 million on geological tests which showed there was potential to find gas when drilling begins.

"This project could be bigger than the North West Shelf - it's the most significant thing we're doing at the moment," Mr Palmer said.

"There's a $16 billion LNG project going on with Exxon at the moment and our gas [site] is right opposite that."

Mr Palmer said the offer from Exxon was "a standing offer" and "we're thinking about it".

"We don't want to make hasty decisions. But we're either going to develop it, joint venture it or do a deal with the Chinese."

Through its subsidiary Esso Highlands, ExxonMobil is already working on the $16 billion PNG liquefied natural gas project, where construction work has been disrupted by a recent landslide.

Asked about the proposed deal with Mr Palmer, Esso Highlands spokeswoman Rebecca Arnold said: "It's not ExxonMobil's practice to comment on commercial matters."

Mr Palmer declined to discuss the details of Exxon's offer but it is believed that, under the proposal, the company would get a certain percentage of Chinampa's tenements and would have an option to do more drilling down the track.

Chinampa has three exploration licences in shallow to deep water close to the planned LNG plant at Port Moresby.

Mr Palmer plans to make a formal announcement on the offer later this year. Chinampa has also been in discussions with the PNG government on the project.

Last June, Mr Palmer spoke at a dinner that raised about $10,000 for the country's United Resources Party. He has described PNG as "the promised land" and is hoping to find oil and gas to sell to China for the country's growing energy needs.

"If we find gas, we develop it and make billions of dollars out of it," he said.

"First we're looking at reserves and then the cost of extracting . . . But it looks very promising." There's a real need for more energy in the world."

Mr Palmer claimed the $40 million spent on 3D seismic geological tests revealed 22 trillion cubic feet of gas.

"We looked at a comparative company in the US with that many reserves and with that amount it's worth about $60 billion [in market capitalisation]," he said.

Oil and gas experts said while the geological tests would indicate a potential for drilling, it was too early to tell its value. PNG LNG is scheduled to start shipments to its Asian customers in 2014.

One expert who wished to remain anonymous said: "Exxon Mobil are very good at what they do and don't look at something unless they think there's potential."

Further Commentary by Prof Petley on the NDC 'Report'

By Prof Dave Petley

Wilson Professor of Hazard and Risk in the Department of Geography at Durham University in the United Kingdom. 

(Originally Posted on the Landslide Blog)

Several people have asked what I mean by a proper landslide investigation with respect to the report on the Tumbi Quarry landslide.  To illustrate, one might compare these two reports:

1. The Tumbi Quarry landslide report, prepared by the National Disaster Center.

2. Report on the landslide that blocked SH 1 and the railway line near Rosy Morn Stream south of Kaikoura on 10 September 2010, prepared by GNS Science as part of the Geonet programme.

The GNS report is not long, and nor is it highly detailed.  However, it is throrough, it investigates and describes the landslide properly, and it allows evidence-based conclusions to be drawn about the landslide and its triggers and causes.

This should be the minimum level of report for a major landslide event.  Of course, in New Zealand (or indeed the UK) a landslide that killed 25 or more people would probably be investigated in very much more detail*.

*LNG Watch: The O'Neil government has demonstrated the capacity and willingness to conduct such an inquiry with respect to the MV Rabaul Queen disaster (it will be led by a retired Australian judge and will include international experts). The same will and capacity appears to be lacking with respect to the Tumbi disaster. Facebook contributors have asked the question, is ExxonMobil the critical difference.  

Money for ExxonMobil Yes; Money for Victims No!

This was published today by the Post-Courier/Pacnews, note the contrast to our previous post. This is reflective of a state that is run by and for the elite.


More than two weeks after the Tumbi landslip at Hides near the multi-billion kina LNG project site in Tari and authorities have made no efforts to retrieve the 25 or more bodies still buried in the landslide.

Hela Provincial Police Commander Supt John Anawe, who is co-ordinating the emergency and relief centre at Nogoli, said it would take some time before rescue workers move in and try to retrieve the bodies believed to be buried alive in the January 25 disaster.

Supt Anawe said it was likely that a mass graveyard would be declared in the landslide site if efforts to retrieve the bodies fail.

He said officers from the National Disaster Office in Port Moresby visited the disaster site last week and they were yet to finalise relief assistance to the relatives and victims of the disaster.

In the last few days, local authorities have had closed door meetings with the Local Disaster Management team, developers Oil Search and Exxonmobil, disaster officers from Port Moresby, Police and other stakeholders. 

The outcome has not be established so far.

Meanwhile, locals told the Post-Courier at the disaster site yesterday evening that the authorities are yet to give them relief support and compensation money.

This is despite the K10m that has been allocated last week by the National Government for emergency assistance to those affected by the landslip.

Locals also said the disaster was caused by heavy explosions, drilling and the development of the quarry for the LNG project and Exxonmobil must take full responsibility for the lives lost and properties destroyed in the disaster.

They also warned that they would not allow work to re-open in Nogoli, Hides and Komo highway if they are not compensated.

Fuel and supplies bound for the LNG sites at Komo and Hides 4 areas are fast running out due to the road blocks, and work on the LNG sites have been disrupted for two weeks now..


SOURCE: POST COURIER/PACNEWS

$4.5 Million US to Help ExxonMobil the 'True Victim' of the Tumbi Landslide

Can you believe it, the national government hasnt the resources to put together an investigation report on the Tumbi disaster that would pass 1st year university, but they can clear the road for their friends ExxonMobil. 


Landslide stops work at ExxonMobil's airport project


Radio New Zealand, 8 February 2012


The Papua New Guinea government has allocated more than four and a half million US dollars to clear a road damaged by a recent landslide, so that the Exxon Mobil airport project can resume in the Southern Highlands region.

The landslide struck in the vicinity of Exxon Mobil’s liquified natural gas project’s Nogoli base, burying a village and killing at least 25 people.

The minister for Transport and Works, Francis Awesa, says Exxon Mobil has also contributed money to have the road cleared.

Mr Awesa says it will benefit villagers in the Komo district as well as Exxon Mobil’s airport project, which has come to a halt since the landslide.

“In the Komo area work stopped because there’s no fuel, you can’t get fuel in there because the road is blocked so we’re trying to get the road cleared in order to get fuel in there and people, villagers and government officials moving in and out of the area, and then the project personnel and contractors.”

Francis Awesa says they hope to get road access in the next few weeks.

Landslide Expert Appraises National Disaster Commission Report on Tumbi Landslide

By Prof Dave Petley

Wilson Professor of Hazard and Risk in the Department of Geography at Durham University in the United Kingdom. 

(Originally Posted on the Landslide Blog)

The National Disaster Council of Papua New Guinea has posted online a report into the Tumbi Quarry landslide (see previous posts here, here, and here).  Presumably this is the “official investigation” that was promised.  They should be credited with making this available online, and the document has some useful information on, and images of, the landslide.  It is also helpful to get the official view on the landslide event, and there is a management plan for the victims and survivors of the accident.

However, there are aspects of the report that are perhaps interesting, as follows:

1. The report only very briefly mentions the quarry.  The report states that “naturally high geological weaknesses assisted by abnormally high rain fall combined to cause subsidence to the immediate north west of the quarry triggering a landslide of composite debris.”  The image on the front cover clearly shows a part of the quarry, with some of the benches truncated by the lateral margin of the landslide:

The report is ambiguous as to whether this means that the landslide was associated with the quarry.  It maybe that the quarry access / haul road also crossed the area now destroyed by the landslide (as per the Esso Highlands plan), and yet this is also not discussed.  Clearly at least a part of the quarry was lost in the landslide, so a proper discussion of whether the quarry played a role in activating these weaknesses seems essential to me.

Note also that these naturally-occurring geological weaknesses are not described or discussed (I assume that this means a set of joints?), and the mechanism of “subsidence” is also quite strange.

2. The landslide trigger is definitively described as being rainfall, on the basis that there was no recorded seismicity.  However, although “continuous heavy rainfall” is described, there is no data to support this, and no eye-witness reports.  The next sentence talks about “abnormally high rainfall”, but I can find no other reference to this event.  I wonder what evidence there is for this abnormal rainfall event, given the high rainfall that this area is likely to receive anyway.

3. There are odd aspects of the landslide mechanism as described in the report  First, the report notes that pools and seepage on the shear face indicate that the “ground water rose significantly above its historical levels”.  I do not understand this logic.  Seepage and pools are likely to occur in the aftermath of almost any deep landslide of this type, and I do not see why they indicate that the groundwater levels were abnormally high, or indeed that groundwater even played a substantial role.  Second, the report notes that the initial assessment team “saw clear evidence of liquefaction of the rock formation”.  This is most surprising.  Limestone is not a material that undergoes liquefaction – I have never heard of such a mechanism in a hard rock – and so I just cannot understand this purported process.  Unfortunately, it is not discussed further.

So overall, whilst the description of the site is really helpful, though it would be good to see a more detailed consideration of the ways in which the quarry might have been a factor in activating these geological weaknesses.  In designing a quarry it is normal practice to ensure that such natural weaknesses are not exposed to the point that they can permit slope failure to occur.

To my mind this report should not be considered to be the definitive analysis of this landslide.  Much more detailed analysis is needed, and lessons need to be learnt in terms of other slopes in Papua New Guinea.

Investigating the Tumbi Quarry landslide in Papua New Guinea

By Prof Dave Petley

(Originally posted on the Landslide Blog)

Despite widespread calls for an investigation of the Tumbi Quarry landslide in Papua New Guinea, and a pledge from the PNG Government to undertake such an inquiry, there is little evidence of action.  Given the suggestions, at the moment with no hard evidence either way in the public domain, that quarrying operations for the Exxon-Mobil LNG pipeline project may have played a part in the initiation of the landslide, this is somewhat unfortunate.  RNZIhas today posted an article from which this quote is taken:

“Christine Yango denies that the project is to blame for the landslide, saying it was a natural phenomenon which has nothing to do with nearby LNG activity”

Christine Yango is the Liaison Officer with Oil Search, one of the partners in the LNG Project.  If this quote is true then it appears that the company has already come to a conclusion about the landslide.  I wonder as to the basis for this.

So lets just summarise what we know about the landslide.  First, the landslide is located at, and indeed has destroyed, the Tumbi Quarry site.  This is clearly evident from the first image that I posted:

The remains of what I infer to be the quarry roads and cuts are located in the upper right part of the image, although most of the works appear to have been destroyed.  It is interesting to note that there is no real sign of the spoil (e.g. topsoil) from the quarry works – I wonder where the dump sites for this were located (this is peculiar given the indicative locations in tha map below)?  If downslope or upslope of the main quarry area then this may have been a factor in the development of instability.

Second, the LNG project documentation clearly states that a quarry at this site was to be used in the LNG Project for aggregate extraction.  On page 6 it states that “Tumbi Quarry, known as QA1, is required for aggregate to be used by the Project in the Komo area”.  The document even provides a map of the proposed quarry (see page 10 of the pdf):

To gain an understanding of the orientation, the photograph above has been taken from the northeast looking southwest onto the site.

This indicates that the quarry site was located right in the middle of the section of slope that has failed.  It is bold to suggest that the two are not linked without undertaking a proper investigation.

Finally, if this is a natural slope failure, I wonder what was the cause?  The images do not suggest that heavy rainfall was occurring at the time, and I have seen no indications of earthquake activity.  It is true that progressive failure sometimes means that a slope fails without a trigger, but if so then the site would have shown  extensive evidence of deformation – e.g. cracks, grabens, lateral scarps, etc.  If the ground showed such features then these would normally be picked up in the ground investigation prior to the extension of the quarry, and during routine monitoring as the quarry was developed.  If such features were present, the quarry is unlikely to have been developed – the risk of failure would have been too high. And if they were picked up in routine monitoring, action would have been taken immediately as slope failures are a major threat to quarry operations.

So there is a real contradiction here that needs addressing:

• If this was a natural (i.e. progressive) failure, as the liaison officer suggests, then why weren’t the surface features of the landslide picked up prior to the construction of the quarry, and indeed during quarrying operations?
• But, if these indications of failure were not present, then the slope failure was most likely triggered by a short term process – which would normally be one of intense rainfall, seismicity or human activities.   Which of those was occurring at the time of the landslide to trigger it?

Maybe there is a simple explanation for this contradiction, but at the moment I am unsure as to what this might be.  Of course an independent investigation would find this.  Personally, I would have thought that it would be in the interests of Exxon-Mobil to undertake such an investigation in order to clear up the uncertainty regarding the role of the quarry in the initiation of this landslide.

Meanwhile, judging by the media reports a major concern of the pipeline developers appears to be the logistical challenges associated with the loss of the road.  Again, quoting the RNZI article, Christine Yango is quoted as syaing:

“Yeah I think people are waiting. But we can’t deny the fact that the road system is cut off because of the landslide. It affects major infrastructure areas: the Hides gas conditioning plant and the Komo airfield; the road that brings all the supplies and things. I think at the moment that for food rations and things like that, they’re using air transport, helicopters, but they haven’t cleared up the area to allow vehicles to pass through yet.”