This blog provides a commentary on landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings. The blog is written on a personal basis by Dave Petley, who is the Wilson Professor of Hazard and Risk in the Department of Geography at Durham University in the United Kingdom.

This blog is a personal project that does not seek to represent Durham University.

Saturday, 30 October 2010

Reports suggest that the Kolontar dam collapse was associated with foundation failure

Thanks to Peter Diehl for his continued hard work with this issue.

See the full blog post on the new AGU blog site.

Friday, 29 October 2010

An amazing landslide video from Manaus in Brazil

Over the years I have featured many videos of landslides in action, some amazing and some less so. Today's example is right at the amazing end of the scale. This slide appears to be a quick clay type (see earlier examples here and here) event and that it occurred on 17th October at Port Chibatao (shown above before the landslide) in Manaus in Brazil. Note that this is an inland port in the centre of Brazil on the Amazon. The video should be visible below:

Continue this post on the new site for this blog

Thursday, 28 October 2010

The new AGU Blogspace site is now live!!!

As you are I am sure aware, this blog is moving to the new AGU Blogspace.  Well, today is the day - a little later than planned, but I hope you will feel that it has been worth it.  The new home for the blog is here:

And the home site for all seven AGU geoblogs is here:

As you will see from the screenshot below, the new blog is cleaner, crisper, has better functionality, no ads and is hosted by an earth science organisation rather than a connercial site.  I am really excited about the possibilities that this move will provide:

So please come on over and take a look, and let me know what you think.  My intention is to run the two sites in parallel for a few weeks, then to move to a phase of just posting titles with a link here and ultimately to cease using this site altogether.  However, the archive will remain intact (although all the content on this site is also now on the new site as well.

Wednesday, 27 October 2010

The Mantawai islands tsunami and the eruption of Mount Merapi in Indonesia

Indonesia is today trying to deal simultaneously with two substantial natural hazards of a rather different nature.  The earthquake on Monday 25th October triggered a localised tsunami in the Mentawai islands, close to the epicentre, the Reuters Alertnet reports killed 108 people and has left a further 502 people missing. 

The data on the earthquake available on the USGS website suggest that this was a Mw=7.7 event at a depth of about 21 km.  The earthquake occurred on the subduction boundary between the Australian and Sunda plates.  This is the same fault system that has generated a series of earthquakes in recent years, the most notable of course being the 2004 Boxing Day tsunami generating event.  This area has been known to be due a large earthquake in the current series - see for example this article on the BBC website, which provided the map shown to the left, identifying the area of concern.

The location of the earthquake was such that the potential for widespread damage from the event itself was limited given the lack of population in the immediate vicinity.  However, the potential for a local tsunami was immediately identified and warnings were issued.  The tsunami itself appears to have primarily affected the islands of North and South Pagai (see map below).  The charity Surfaid is very active on the Mentawi islands, and of course some of the villages affected by the tsunami are surfing sites, so unsurprisingly it thus has some good reports about the event itself.  The earthquake struck at 9:42 pm local time - i.e. when  it was dark - which of course will have reduced the likelihood of seeing the onrushing wave, and the likelihood of escaping from it somewhat lower. 

At the moment there is little information as to the likely cause of the tsunami.  It is possible that this was directly generated by the earthquake, or that it may be associated with one or more submarine landslides.  However, the GDACS service has a quite excellent but poorly-advertised resource online here that provides an animation of the likely tsunami generated by the fault itself here.    The animation should be visible below:

The resultant wave heights are shown below:

Their modelling data suggests arrival wave heights of 0.1 to 0.5 metres, somewhat lower than actually reported (Surfaid suggests 2 to 3 metres), but note that this could be any one of the run-up affect when the wave reaches the coast, deficiencies in the model (which inevitably is only taking a very broad view at this stage) and the impact of events such as submarine landslides.

Meanwhile, Mount Merapi has now started erupting, and reports suggest that 25 people have been killed, probably by pyroclastic flows if the reports are correct.  Up to 50,000 people are being evacuated.  This has the potential to be a large eruption.  There is a good set of webcams available here (click on the icons on the map), although in this tropical environment clouds are inevitably a problem.  Note that it takes a minute or so for the image to download, so be patient.  The image to the left is one taken. 

In the last few hours the activity level appears to have reduced, but this should not be taken to indicate that the crisis is coming to an end.  There is the potential for a large eruption, but others are better placed to comment than am I.  To this end, I would recommend two blogs: Erik Klemetti's Eruptions blog, which already has material on this event online, and Ralph Harrington's The Volcanism Blog

Merapi killed 64 people in pyroclastic flows in 1994 and 1,300 people in pyroclastic flows in 1930.  In both cases lahars (volcanic landslides) were a major problem in the aftermath of the eruptions, so the authorities caution is well-placed.

Monday, 25 October 2010

Landslides, forests and pandas - conservation and the Wenchuan earthquake

ResearchBlogging.orgThe vast number of  landslides triggered by the May 2008 Wenchuan earthquake, and in its aftermath has been extensively described, not least on this blog.  One of the documented impacts of these landslides was the well-documented loss of habitat of the giant panda (A. melanoleuca) due to extensive forest loss.  However, there is a great deal more to that story than meets the eye, as a newly-published paper by Vina et al (2010) describes.  The research is very interesting, and has some quite substantial implications for landslide management in earthquake-prone areas.

Sunday, 24 October 2010

Landslides from typhoon Megi in Taiwan

The passage of typhoons past or across Taiwan often leads to the generation of exceptionally high rainfall totals that, when combined the steep topography and weak rocks, inevitably triggers extensive landsliding.  The late season typhoon Megi, whose erratic course meant that it somewhat unexpectedly brought heavy rainfall to Taiwan at the end of last week, was no exception:

Thursday, 21 October 2010

The curious story of the Rajang log jam in Sarawak, Malaysia

An interesting if somewhat strange story has developed in Malaysia over the last few days.  The Rajang River flows over a distance of about 560 km across Sarawak.  It is fairly obvious on this Google Earth image:

Update on the move to the AGU blogspace

The move to the AGU site has been delayed by a few days to allow some minor technical gremlins to be cleared.  As a result I do not anticipate moving to the new location (and name) until early next week now. I will continue to post here as the primary location until at least Monday.

Wednesday, 20 October 2010

One day to go...

As you are probably aware, this blog is about to migrate to an AGU hosted web site.  All being well, the blog will move late tomorrow (21st October).  I am hoping that there will be no interruption along the way.  I will post the new location in the next few hours and plan to run the two sites in parallel for a few weeks.

One minor change that I have decided to implement is that the blog on the new site will be called "The Landslide Blog" rather than "Dave's Landslide Blog". 

Tuesday, 19 October 2010

Two fatal landslides in the earthquake affected areas of Haiti

Problems continue in the earthquake affected areas of Haiti, where over 2 million people remain essentially homeless 10 months after the devastating earthquake.  Reporters Live are carrying a story that heavy rainfall in the last 48 hours has triggered two, rather different fatality-inducing landslides:

Typhoon Megi and the Philippines

In the last 24 hours Typhoon Megi has tracked from east to west across northern Luzon in the Philippines (map from here):

5th Canadian Conference on Geotechnique and Natural Hazards

Thanks to Rick Guthrie for pointing out in a comment another interesting Canadian conference on natural hazards.  This is the 5th Canadian Conference on Geotechnique and Natural Hazards, also known as Geohazards 5, which will be held in Kelowna, British Columbia on 15th to 17th May 2011.  

The call for abstracts closes on 29th October, and includes papers on the following:
  • Seismic hazards
  • Flooding and natural dams
  • Landslides
  • Quantitative risk assessment 
  • Snow and rock avalanches
  • Technology and geohazards - monitoring and remote sensing
  • Geohazards in a changing climate
  • Tsunamis 
  • Early warning & response
  • Urban hazards and policy development
  • Volcanoes 
Details are available at the conference website:

With sesveral landslide sessions at the AGU Fall meeting in Decembermultiple landslide sessions at the EGU General Assembly in April, Geohazarads 5 in May, and Slope Stability 2011 in September the next 12 months look excellent for landslide meetings.  Further out, we have the 11th International Symposium on Landslides in May 2012

See you there!

Sunday, 17 October 2010

Updated: Attabad - NDMA make a full set of reports available online, plus an article in the Economist

The National Disaster Management Agency (NDMA) in Pakistan have now made four reports about Attabad available online here.  These are as follows (with the correct links to each):
  • The dam break study undertaken by NESPAK.
  • A report by Alessandro Palmeiri, from the World Bank
  • My report on the landslide.
  • A report by the Geological Survey of Pakistan dating from before the landslide event about the hazards at the site.
Interestingly, although my report is included NDMA have not asked my permission to post it there, and nor did they inform me that they had done so.  Indeed, at no stage have they communicated with me about Attabad, beyond a single line reply to an email that I sent to them.  However, I am pleased that my report is easily available.

Update: The Economist has today also published a short article on Attabad, which is available here.  Meanwhile the Express Tribune reports that the long-promised compensation will finally be paid to the local population, and that deepening the spillway will start within a month.  Finally, there are two Attbad related papers being presented at the forthcoming AGU conference in San Francisco:
  • Hunza Landslide and Monsoon Flooding in Pakistan Call for International Attention to Transboundary Natural Hazards by J. S. Kargel; W. Fink; R. Furfaro; G. J. Leonard; M. Patterson. 
  • Satellite Monitoring and Characterization of the 2010 Rockslide-Dammed Lake Gojal, North Pakistan.  by G. J. Leonard; J. S. Kargel; R. E. Crippen; S. G. Evans; K. B. Delaney; J. F. Schneider

Saturday, 16 October 2010

Round up of landslide stories and events for the last week

In weeks in which I have been too busy to post a great deal of material, I often provide a summary of interesting landslide events around the world.  This is the summary for the last week:

1. A very strange landslide in Germany

Thursday, 14 October 2010

Some statistics on disasters worldwide

 Yesterday was the annual United Nations International Day for Disaster Reduction, which this year had a strong urban theme.  To highlight the event, which has been somewhat overshadowed by the extraordinary rescue of the Chilean miners, UNISDR put out a press release highlighting the costs of disasters worldwide.  The statistics are somewhat sobering:
  • So far in 2010 more than 236,000 people have been killed in disasters
  • 256 million people have been affected by disaster events, mostly in urban areas
  • The cost of disasters in the first nine months of this year is US$81 billion.  Most losses are uninsured
With regard to the vulnerability of urban areas:
  • More than a billion people live in urban slums
  • An estimated 3,351 cities are situated in coastal zones that are potentially vulnerable to sea level rise
  • Six of the ten largest cities are in seismically active areas
To mark the day, Xinhua released statistics on disaster impacts in China this year to date:
  • Floods, landslides and mudslides have killed 3,313 people so far this year
  • 15.7 million people have had to relocate
  • Economic losses are estimated to be a staggering US$55.4 billion

Wednesday, 13 October 2010

Important news about this blog

As Dave's landslide blog approaches it's third anniversary, I have some important news about the future of the site. As you are aware, the blog currently sits on blogger, which is a commercial blog site owned by google. Whilst it has served the purpose well, I would rather it was located on a proper science-led site. A few months ago I was approached by the AGU, the world's largest earth science organisation, with an offer to host the blog. After discussions I have accepted this great suggestion, so the blog will move,, hopefully in the next couple of weeks, to the new site. The plan is that this blog will be one of a collection of seven or so geoblogs on the AGU blog site. I will provide details of the new site, and of the other blogs that are moving there, in the next few days.

The move will cause some disruption, but I hope this can be minimised. My plan is to run the new site and the original site in parallel for a few weeks. Otherwise there will be no major changes to the site - I will retain full editorial control of the blog.

Tuesday, 12 October 2010

Slope Stability 2011

The website of the latest in an excellent set of Canadian conferences on slope stability and instability is now available at the following link:

The meeting will be held on 18th-21st September 2011 in Vancouver.  The focus is on  Rock Slope Stability in Open Pit Mining and Civil Engineering.  The call for papers is now out, with abstracts due by 31st December 2010. 

This meeting serves as a nice aperitif to the International Symposium on Landslides, which will be held in Banff, Canada in June 2012.  Abstracts for that meeting are due on 15th April 2011.

Monday, 11 October 2010

Images of the top surface of the Ajkai Timfoldgyar / Kolontar tailings dam

The website has a set of images taken of the top of the dam at Ajkai Timfoldgyar / Kolontar.  These are helpful in confirming observations from the aerial imagery featured yesterday that a section of the tailings dam has moved.  This images shows the pipe running across the top surface of the dam:

Sunday, 10 October 2010

Further insights into the failure mode of the Ajkai Timfoldgyar (Kolontar) tailings dam

Thanks once again to Peter Diehl, the causes of failure of the Ajkai Timfoldgyar / Kolontar tailings dam are becoming clearer, and appear to support initial suspicions.  There is an excellent gallery of images here, of which this is the most interesting in this context:

Saturday, 9 October 2010

New aerial images of the Ajkai Timfoldgyar tailings dam site

Thanks again for Peter Diehl for his help with this one.  Greenpeace have collected and released some oblique aerial images of the site at Ajkai Timfoldgyar (Kolontar) that are revealing.  They are available on the Der Standard website.  The best image of the dam itself is this one:

Note the crack in the dam surface on the left side of the image. It is also worth noting that the dam structure on the left side of the breach is rather different from that on the right.   Finally, note the interesting shape of the fracture on the left side of the breach.  I continue to be interested in the foundation of this structure, although I would also be interested to know a little more about the transition between the dam structure on the left side and that on the right side of the breach.

Meanwhile, Peter has also tracked down the aerial video imagery of the breach.  This can be accessed here.

Friday, 8 October 2010

September 2010 fatal landslide statistics

Most readers will be aware that I collate statistics for fatal landslides occurring worldwide. I have now processed the statistics for September, and the results are as follows:

Thursday, 7 October 2010

The Ajkai Timfoldgyar tailings dam disaster: Lessons from the Los Frailes tailings dam failure in Spain

The clean up at the Ajkai Timfoldgyar tailings debris flow accident site continues today, with continued concern about the potential for pollution of the downstream rivers from the environmentally-damaging debris.  I do not wish to speculate on the cause of this accident, but will note that foundation failure is a well-established failure mode for tailings dams - see for example the excellent site, which has a section on typical tailings dam failure modes here.  Top of the list is "hazard from weak foundation", which describes a situation when "the soil or rock at shallow depth below the dam is too weak to support the dam, movement along a failure plane will occur. This may result in partial or complete failure of the dam."

The classic example of this occurred on 25th April 1998 at the Los Frailes tailings dam in Aznalcollar in Spain.  Good images of this event are hard to source, but this one is helpful (source):

The sequence of the failure at this site was quite complex (see description here), with the initiation occurring as a result foundation failure in a separation dam between two parts of the tailings pond.  This occurred as a result of a failure on a weak plane in the foundation of the dam at a depth of about 14 metres.  The dam slid forwards and cracked, allowing the release of the tailings, as this image (from here) shows:

As can be seen above, the failure of the foundation of the dam caused it to be pushed forward by up to 60 metres. This accident was essentially a failure in design - i.e. the designers did not adequately consider the strength of the marl layers below the dam foundation and the likely build up of pore pressures in this area.

It is interesting to note the similarity between the images of the Ajkai Timfoldgyar and the Los Frailes events (compare with the image here), and also that the event in Hungary on Monday occurred after a prolonged period of heavy rainfall.

There is an excellent gallery of the downstream impact of this failure here.

Whatever the cause of this accident, far too many tailings accidents are happening around the world.  As an illustration see the following previous posts on this topic:
Tailings dam failures and the price of commodities
Another Chinese tailings dam failure
A useful tailings dam failure resource
Another Chinese flowslide?
China tailings dam disaster death toll

The authorities really need to start to regulate this bette.

Wednesday, 6 October 2010

Interesting images of the Ajkai Timfoldgyar tailings dam accident in Hungary

As predicted, a number of interesting images are now available of the site of the breach that caused the Ajkai Timfoldgyar tailings debris flow in Hungary on Monday.  Thanks again to Peter Diehl for his tireless work in seeking out and highlighting the best images.  The best slide show, surely destined to become an invaluable teaching aid, is available at this link:

Tuesday, 5 October 2010

The Hungarian tailings dam accident - images of the failure of the impounding embankment

Thanks to both  Peter Diehl, PeterOi and an anonymous commenter for pointing out the locations of images of the embankment that failed to release the landslide of toxic sludge in Hungary.  The best one is probably this image, from Der Standard in Austria:

Tailings landslide in Hungary and a dam crisis in Vietnam

News today, barely covered in the international mainstream media so far, of a new tailings-related landslide in Hungary yesterday.  The only English report that I have seen so far is on the Chinese CriEnglish website, which reports that 700,000 cubic metres of bauxite ore formed a flow that struck three villages in Veszprem county.  These villages appear to be Devecser, Somlóvásárhely and Kolontar. 

Sunday, 3 October 2010

Continued debris flow activity in the Wenchuan (Sichuan) earthquake area

A frequently-forgotten but potentially very damaging impact of large earthquakes in mountain areas is the increased occurrence of debris flows and other landslides in the following years.  Whilst these events continue to represent a hazard in their own right, they frequently also cause changes to river dynamics, with resultant high levels of damage.  This problem was illustrated all too clearly in a small village that we visited close to Beichuan last week.  For those who would like to locate the village. my iPhone GPS said that we were at 32.13N, 105.54E.  This small, remote village of about 200 people lost about 20 residents in the earthquake itself.  However, the real impact has come in the aftermath.  This small factory was main source of employment in the area.  It survived the earthquake but has been destroyed by repeated debris flows that have occurred every summer since the earthquake:

Saturday, 2 October 2010

Beichuan town - the old and the new

On Wednesday I was fortunate to be able to return to Beichuan (see my images of the town, taken last year), the heart of the earthquake-affected areas in Sichuan.  Well, to be more accurate I visited the viewpoint looking down on the town.  It is clear that debris flows continue to be a major problem at this site:

For those who don't know the site I have annotated the image below to point out the key features:

Meanwhile, about 25 km away on the plain the new town of Beichuan, replacing the settlement above, which will be preserved as seen, is almost complete.  We called in on the way through - it is an astonishing place.  This has been constructed at a cost of 15 billion Yuan (US$2 billion), of which just under 10 billion Yuan has been spent to date.  It will ultimately be the home of 70,000 people, and the administrative headquarters of Beichuan County. These images show the new town in the week of hand-over.  First an aspiration as to what it should look like, according to a billboard at the site.  Note the western brands (Calvin Klein, McDonald's):

Somehow these image feels a little sad.  Here is the reality of one of the many residential areas:

And here is one of the streets, which have been built with cycle lanes:

Pleasingly, there is a very strong attempt to retain a strong traditional sense to the architecture of the central parts of the town, as shown by this bridge across the river:

I hope this is a huge success - the people of Beichuan deserve it.