Dave's Landslide Blog

Intriguing landslide of the week – catastrophic bluff collapse at WE Energies plant at Oak Creek in Wisconsin

2011-11-01T08:15:00.002Z

Summary: An initial report of a landslide that occurred yesterday at the WE Energies electricity generating station in Wisconsin, USA. Some thoughts on possible causes are included.

In Wisconsin yesterday a landslide occurred at the WE Energies power station complex near to Oak Creek in southern Wisconsin. This is the site, which is located on the western edge of Lake Michigan:

The landslide has occurred on the southern side of the complex in an area that is being developed for pollution control equipment (presumably sulphur scrubbers or suchlike). It appears to be a fairly mobile flow slide that covered an area that is reported to be “the size of a football field”:

Read the rest of this post on the new site

Aberfan - 45 years ago today

2011-10-21T13:05:00.000+01:00

Introduction

The story of the Aberfan disaster is seared into the memories of a generation of people in South Wales, and it remains a tragedy of huge proportions. Today, 45 years on from the disaster, there is much to learn from the events leading up to, and that occurred on, the day. In this article, we seek to explain the events that occurred in Aberfan on 21^st October 1966, to review why the disaster occurred, and to examine the aftermath. Finally, we briefly examine the legacy that this disaster has left in many spheres of life.

Read the rest of this post

First news of the Mw=6.3 earthquake in Christchurch, New Zealand

2011-02-22T02:43:00.000Z

Because of the severity of this event I have as a one-off posted on this blog. All updates will appear on the new AGU website.

Christchurch in New Zealand was once again hit by an earthquake today, with the event happening at 12:51 pm local time (23:51 UT on 21st Feb). As usual, the Geonet site is the best place for up to date information about this event. At the time of writing (just over two hours after the earthquake, the location report is as follows:

A Google Earth image of the location of the epicentre shows why this earthquake is likely to have had a huge impact:

Note the reported location of the earthquake at the foot of the image. In essence this is a bulls-eye hit of a substantial event on the city. The Geonet reported magnitude is 6.3 (note that this is likely to change over the next few hours as the data improves), but the depth is very shallow (only 5 km). The consequence is high levels of shaking in the city centre. The Geonet shaking intensity map is based upon instrument data and reports by people on the ground. As I write the map looks like this:

The squares are the instrument data, and the circles the eye-witness reports. The red squares indicate MM=8 and the orange ones MM=7. Christcurch itself is in the MM=7 zone, which in terms of buildings is "damaging".
Christchurch is probably the most "English" city in Australasia, which means actually that there are at least some masonry buildings. An example is the cathedral - the picture pair below shows after (from here) and a file image from before the event:

The likely impact of the earthquake is likely to have been exacerbated by the timing in the middle of the day, which means that many people will have been in the street (unlike the September 2010 (Darfield) event, which occurred very late at night). This means that many more people will have been in the way of collapsing buildings, breaking glass, etc. Fatalities are very likely as a consequence. Liquefaction was also a major issue in the Darfield earthquake, and is likely to be a major problem in this case too.

Readers may be interested in my images from the aftermath of the September 2010 (Darfield) event, which can be found here (the famous railway line images), here (the fault rupture) and here (building damage).

Because of the severity of this event I have as a one-off posted on this blog. All updates will appear on the new AGU website.

Last post on this site

2010-12-07T21:58:00.000Z

This is the last post on this, the Blogspot / Blogger site. From now on everything will be on the new AGU blog site - you can access it here:

http://blogs.agu.org/landslideblog/

My first post was on 16th December 2007, almost exactly three years ago. The first image that I posted showed the La Honda landslide in California, so I will finish here with a Google Earth image of the same site, taken at about the same time. Spot the displaced road...

So long and thanks for all the fish,

Dave

Early reports of a serious landslide in Colombia

2010-12-06T06:56:00.002Z

Read this post on the new AGU blog site.

Dramatic footage – coastal landslides in Canada and a snow avalanche in Edinburgh!

2010-12-06T02:50:00.000Z

Read the post on the new AGU blog site.

My new position from January: Executive Director of the Institute of Hazard, Risk and Resilience

2010-12-03T09:43:00.000Z

Apologies for the paucity of posts over the last fortnight – I promise that normal service will shortly be returned! I am currently somewhat rushed off my feet. You may know that my current job is split between two roles – nominally I spend 30% of my time on my own research, including fieldwork; conferences; supervising PhD students and post-docs; writing papers; refereeing; replying to emails; and, of course, writing this blog! The other 70% of my time is spent helping to run the Faculty of Social Sciences and Health (Faculty in this context is the European not US meaning – i.e. it is what is often referred to in the US as a College, although confusingly that word has a different meaning for us as well). In particular, I look after research and enterprise activities across nine academic units, including the Medical School, Archaeology, Anthropology, Education, Law, Geography, Government and International Affairs and Applied Social Sciences, and various associated units and centres.

From the middle of January I will give up this role to move to something new and exciting. At this time I will take over as the Executive Director of the Durham University Institute of Hazard, Risk and Resilience.

Read the remainder of this post at the new AGU hosted home of this blog.

Update on the Tawang Monastery and a good article on the tribulations of Pakistan

2010-11-29T20:38:00.000Z

Update on Tawang
Thanks to reader Adrian Moon for tracking this down – an image of the landslide affecting the Tawang Monastery site in India has been posted on the Echo of Aranchal website:

Click here for the rest of the post on the new site.

Acute landslide threats to the Tawang Monastery, northern India

2010-11-28T21:41:00.000Z

One of the most important sites of Buddhist worship is the Tawang Monastery in Himachal Pradesh in northern India. This site, which is home to an estimated 450 lamas and houses many ancient scriptures and other manuscripts. One of its greatest claims to fame is that the Dalai Lama went first to Tawang when he fled Tibet in 1959. It was founded in 1680-1681, and consists of a collection of many and large small buildings, as shown below (image source):

The extraordinary hilltop location of the site is shown in the Google Earth satellite image below - take a look on Google Earth at 27.59N, 91.86E. The site is located at an elevation of about 3,300 metres. The monastery is located on a site that is quite asymmetric, with a steep front side (eastern) slope and an even steeper, densely forested backslope to the west behind the monastery:

It appears to be an incredible location that even I, as an avowed atheist, would love to visit. Unfortunately, news reports have started to emerge that this site is severely threatened by landslides. For example, the Times of India reported yesterday:

"The Tawang monastery in Arunachal Pradesh, where the spiritual leader stayed in 1959 during his flight from Tibet, has been witnessing massive landslides around it since Monday. The 330-year-old monastery, also known as Gaden Namgyal Lhatse, stands on the spur of a hill about 10,000 feet above sea level. Landslides have already damaged the plantation and electric posts around it."

Unfortunately it is hard to know just how bad this problem might be, although the reports suggest that a plan is being formulated. The cause of the landslides will be an interesting aspect to investigate, given that this is the dry season, well after the monsoon. However, a quick look at the Google Earth imagery in perspective view is not encouraging. In particular, the northern flank of the site appears to consist of a landslide scarp (the area mostly in shadow):

The reasons for this are clear - the river, which flows towards the south, is eroding the toe of the slope due to the site being on the outside of the bend. In the long term erosion at the toe will need to be prevented if the site is to be preserved. The proximity of the buildings to the crest of this slope is clear:

Even if the landslide activity at this site reduces before major damage is done, I would think that there needs to be a fairly urgent landslide management plan for this site if it is to be preserved. Unfortunately, this will not be a cheap or easy exercise.

The Pike River Coal Mine accident

2010-11-19T08:34:00.001Z

Although the key focus of my research is landslides, I also spend some of my time working with mining companies. Thus, the Pike River accident in New Zealand is of interest. The blast today appears to have left at least 27 miner trapped underground; at the time of writing there has been no contact with the missing workers, although rescue operations are clearly underway. All modern mines have fully trained mine rescue teams that lead the way in such events. They regularly liaise with the emergency services, and a contingency plan will be in place.

Landslides in Art Part 8: Goldau by JMW Turner

2010-11-18T08:41:00.000Z

Part 8 of the occasional series on landslides as the subject of art. This edition features a painting of Goldau by JMW Turner, dating from 1843. It shows the aftermath of the September 1806 catastrophic landslide that destroyed the village.
Read more on the new blog site

A round up of interesting natural hazards stories – Taiwan landslides, the Pakistan floods, the Attabad landslide, and risk management in Canada

2010-11-16T20:17:00.000Z

Occasionally I post a round up of stories on natural hazards, mostly on landslides, that have caught my eye in the last few days. Here is the latest set:

1. Taiwan landslide hazard management

Read more on the new blog site

Natural Hazards and UnNatural Disasters – the Economics of Effective Prevention

2010-11-13T11:22:00.000Z

This week a joint publication was released by the United Nations and the World Bank with the above title. The aim of the report, which can be downloaded for free from here, was to exemine the efficacy of investment in disaster risk reduction. Although long, it is an excellent piece of work that is inevitably destined to be influential in this area. As usual with reports associated with the World Bank, which tend to follow a particular economic model for development in less developed countries that has proven to be less than effective in many locations in my view, there are aspects with which I disagree. However, the key points are generally worthy and thought-provoking. As an aside it has been interesting, and slightly depressing to see how little traction this report has gained in the mainstream media. Given the high profile disasters of the last few years this is disappointing.

Read the rest of this post on the new blog

Deforestation, erosion and Cholera in Haiti

2010-11-11T08:45:00.000Z

There is an interesting and provocative recent article on the Huffington Post website by Ethan Budiansky, who works for an NGO called Trees for the Future, which seeks to assist communities and farmers in less developed countries to plant woodlands in order to mitigate environmental damage. The article looks at the issue of deforestation in Haiti, and attempts to link the ongoing cholera outbreak across the country to the rampant deforestation there. That deforestation is an issue in Haiti is beyond doubt - indeed I have blogged on this previously. I am certainly not the first to note that the border between the Dominican Republic (to the east and north in the Google Earth image below) and Haiti (to the south and west - the white line is the approximate location of the border) is visible from the air purely on the basis of the remarkable change in forest density:

Read more on the new blog site

Predicting and cutting landslide risk in developing countries

2010-11-10T07:37:00.000Z

Recently, Professor Malcolm Anderson of Bristol University presented a talk on predicting and cutting landslide risk in developing countries at a Set Squared conference on the impact of university research. This presentation is available online on Youtube and should be visible below. Unfortunately the video does not have the slides, but nonetheless it is a very useful presentation:

Read more on the new blogsite.

The human side of landslides

2010-11-09T08:10:00.000Z

The recent passage of Hurricane Tomas across St Lucia, about which I have posted previously, has left a trail of destruction that has been surprisingly under-reported in the mainstream media. There are some dramatic pictures of the impact of the storm on this blog. Emerging from the wreckage is a very human story of the destructive nature of landslides.

Read the rest of this post on the new AGU hosted blog site.

Landslide fatality statistics for October 2010

2010-11-07T21:16:00.000Z

For those that are new to my blog, one aspect of my research is to maintain a database of landslides that kill people. This has been running since September 2002 (i.e. for eight years so far). So, each month I try to produce a brief report on the number landslide events that have entered the database, and the number of fatalities that resulted. This should be treated as provisional at this stage as I have some further verification work to do.

Read the rest of this post on my new blog site

Hurricane Tomas, Mount Merapi and landslides in Costa Rica

2010-11-05T08:37:00.000Z

With three substantial natural hazard events occurring simultaneously, I thought I would post a round-up of those rapidly-evolving events:

1. Hurricane Tomas

Read more on the new blog

The Rissa landslide - new (old) video available online

2010-11-04T07:54:00.000Z

The original and some would say best landslide video is of that of the April 1978 Rissa landslide in Norway. I have mentioned this slide before - and indeed have hosted a link to the video, although that link is now dead. In looking for background material for the amazing Port Chibatao landslide in Manaus (if you haven't looked at that video then you are really missing out) I found that the section of the original documentary is now available online:

Read more on the new site

Updates – the Canterbury earthquake railway line; Hurricane Tomas and Haiti; and Manchhar lake in Pakistan

2010-11-03T17:54:00.000Z

This is a general update email on a range of recent posts:
1. The railway line affected by the Canterbury Earthquake in New Zealand

Read more on the new blog

The Canterbury Earthquake: images of the distorted railway line

2010-11-02T07:36:00.000Z

Back in September I posted a series of images that I took of the of the surface fault rupture for the 4th September 2010 Mw = 7.1 Canterbury earthquake in New Zealand. Included was this one, taken of a railway line that crossed the fault rupture at the eastern end of the fault near to Rolleston:

Read more by clicking here

A sinkhole in Germany, a landslide in Italy and the forecast path of Hurricane Tomas (which has already caused landslides in St Lucia)

2010-11-01T20:27:00.000Z

Today is one of those days in which there is a great deal going on. Three interesting stories are:

1. A sinkhole in Germany
Thanks to a host of people for bringing the development last night of a sinkhole in the town of Schmalkalden in central Germany to my attention. These feature has been caught in a spectacular set of images...
Read more

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

2010-10-30T08:35:00.001+01:00

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

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

Regular readers will remember the Kolontar dam failure event in Hungary early last month (see image to the left). Based on the images published of the event, I speculated a couple of days later here that the failure of the dam might be associated with problems with the foundations.

In the last week newspaper reports in Hungary have suggested that the investigation does indeed suggest that foundation failure may be the cause of the accident. This article in particular addresses this issue directly. It is in Hungarian, and my skills in that language are somewhat rusty, so I have had to rely upon the Google translation service. My corrected version of the Google translation of the salient part of the article is that the dam was underlain by a slurry / grout wall intended to prevent seepage. However, deformation and fracturing of the soil occurred over a 50 metre stretch, allowing the dam wall to move forwards and fail.

The article says that further investigations are needed, but this would seem like a logical interpretation based upon the evidence available from this distance. It will be interesting to see the nature of the final report in due course, and we must of course be careful not to over-interpret until the final investigation is complete.

An amazing landslide video from Manaus in Brazil

2010-10-29T16:33:00.002+01:00

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

Video:

There is also a nice video of the site after the landslide here:

The slide was apparently triggered by a backhoe working an on exit ramp at the site, according to this article. This small level of disturbance would be enough to start a quick clay slide under certain circumstances. The loss of those cargo containers, mostly full of electronic goods according to the article, is going to be very expensive. It appears that two workers were killed, but this is unconfirmed.

The new AGU Blogspace site is now live!!!

2010-10-28T21:22:00.000+01:00

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:

http://blogs.agu.org/landslideblog/

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

http://blogs.agu.org/

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.

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

2010-10-27T08:46:00.000+01:00

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.

Landslides, forests and pandas - conservation and the Wenchuan earthquake

2010-10-25T21:26:00.003+01:00

The 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.

The study examines forested areas affected by the earthquake in Wenchuan County, in the main area affected by the earthquake. Wenchuan County includes Wolong, the famous giant Panda conservation area. The context for the study is important though - that is that contrary to popular understanding, the forested area of China has been increasing, not decreasing over the last decade or so. There are two key reasons for this:

Economic growth has led to a huge migration of people to urban areas, reducing the pressure on rural resources;
In the aftermath of the devastating floods in 1998, China started a huge programme of forest conservation and restoration, most notably incentivising farmers to return hillside croplands to forest.

So, the key question that this research has addressed is how the dynamics of forests in Wenchuan County. The research team mapped forest cover using Landsat TM satellite images acquired in 1994 and 2001 (i.e. before the conservation effort) and 2007. Augmented with higher resolution IKONOS and Quickbird images from 2000 and 2007. These images were used to map forest cover.

The results are fascinating. Between 1994 and 1991 the forest cover declined from just under 44% in 1994 to about 39.5% in 2001. However, by 2007 the forest cover was back to about 44%, showing that the conservation programmes had generated real results.

The earthquake of course reversed this trend. In the aftermath of the seismic event the forest cover was again mapped using Landsat TM images. The results suggest that 192.6 square kilometres of forest were lost in Wenchuan County, representing just under 11% of the forest cover in 2007. The consequence was that forest cover declined to about 39%. However, the authors estimate that without the conservation programmes this would have been as low 33.5%. Thus, although the occurrence of landslides in the earthquake was truly dreadful, the ecological picture would have been far worse if it hadn't been for the forestry programmes. One aspect that the paper does not cover though is that the loss of forestry increasing seismic landslide susceptibility, and thus the loss might have been greater again

The authors finish by speculating on the long term recovery of the forest resources in the aftermath of the earthquake. They note that the construction of new housing, such as that shown to the left (from my recent trip to the area), is likely to have the effect of moving people away from the more remote rural areas, which may well result in the abandonment of more farmland, and thus increased forest recovery. This may well have substantial benefits for conservation efforts, albeit at potentially high cost to those people most affected by the earthquake.

Reference
Viña, A., Chen, X., McConnell, W., Liu, W., Xu, W., Ouyang, Z., Zhang, H., & Liu, J. (2010). Effects of Natural Disasters on Conservation Policies: The Case of the 2008 Wenchuan Earthquake, China. AMBIO DOI: 10.1007/s13280-010-0098-0

Landslides from typhoon Megi in Taiwan

2010-10-24T07:00:00.001+01:00

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:

Over a 48 hour period the typhoon brought over 1200 mm of rainfall to parts of NE Taiwan. This area is home to one of the world's most spectacular coastal roads - the so-called Suhua Highway, which runs along the east coast from a Su-ao in the north to Hualien in the central east of Taiwan:

This road is popular with tourists both because it is a logical route back to Taipei for a round island tour and because the scenery is spectacular (image from here):

Unfortunately however, this is a very dangerous stretch of road in the heavy heavy rainfall associated with typhoons. During Megi, this is the area that received the most intense rainfall, with the inevitable consequence of extensive rockfalls, rockslides and debris flows. Unfortunately, it appears that a tourist bus carrying 21 people was travelling down the highway at the time of the heaviest rainfall. This bus, which was carrying 19 tourists from mainland China plus their driver and tour guide, is now missing. The bus is likely to have been either buried by a rockslide or to have been involved in a landslide below the road, and thus to have been carried into the sea. The likelihood of survival is very low. Another tour bus was also involved in a rockslide, as shown in the image below (from here).

In this case the passengers escaped, but the driver and tour guide are also missing. Finally, two other vehicles, and their three occupants, are also missing.

Meanwhile, a further nine people were killed in a landslide in Ilan, the main town to the north of the Suhua Highway, when a landslide hit a temple.

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

2010-10-21T21:02:00.001+01:00

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:

A fortnight ago reports emerged that there were navigation problems on the lower reaches of the river. Unusually, these issues occurred not because of high or low river levels, but because the river was choked with wood (a logjam). These impressive images, from http://hornbillunleashed.wordpress.com/2010/10/08/10352/ illustrate the magnitude of the issue. The blockage reportedly extended for 250 km.

The reason that the wood entered the river appears to have been intense rainfall on 6th to 7th October, but the question is where the wood has come from. There are two likely sources of wood like this. The first is that a logging camp or store was inundated (unlikely on this scale); the second is extensive landslides. In Malaysia right now a huge blame game is playing out over the cause of the disaster. The Land Development Minister, James Masing, has claimed that the cause was logging in the catchment. Meanwhile, the state forest director, Len Talif, is blaming shifting rainfall patterns.

The source area appears to have been Sungai Melatai in the Balleh subcatchment, shown here:

Some reports suggest that there was a very large landslide event in this catchment:

A man from Sungai Melatai, a tributary of Baleh River, gave the following account of the cause.
“The cause of the ecological disaster and the extensive environmental damage has nothing to do with the rain or rising water level because on the day it happened the water level along Baleh River was low and normal. There was extensive landslide of between five and 10km on both banks of Sungai Melatai. This has nothing to do with farming activities. It is caused by human disregard for the environment through extensive logging activities." A child died when its mother could not send it for medical treatment in Kapit due to the logjam. Two men in a Land Cruiser died in the landslide.

and

When contacted, the Superintendent of Land and Survey Kapit Affin Bawi said the massive landslide was the culprit. His view was confirmed by an officer from Sarawak Rivers Board. An elderly casual worker identified as Jilan explained that the Ibans described the phenomenon as ‘baruas’ or massive landslide affecting a huge area, when nature gives way.

It is clear that some sort of large landslide event - either a very large slide, or many smaller ones, or even both of those at the same time - has occurred in this catchment. It would be very interesting to know just what has occurred.

Update on the move to the AGU blogspace

2010-10-21T09:45:00.000+01:00

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.

One day to go...

2010-10-20T08:58:00.000+01:00

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".

Two fatal landslides in the earthquake affected areas of Haiti

2010-10-19T08:27:00.001+01:00

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:

1. A collapse in a sand quarry
Illegal quarrying of sand to be used for rebuilding is turning into a major, if unsurprising, problem in the hills around Port-au-Prince. The reports suggest that such a quarry to the west of Port-au-Prince collapsed in the heavy rainfall, killing eight people including two children.

2. Landslide in Carrefour
Meanwhile the article also notes that a second landslide, this time in Carrefour, killed four people and left a further three missing. The report also suggests that "residents likewise said that there had been unreported mudslides that occurred in the last few weeks".

So far this year, Haiti has not been hit by a major hurricane, although we are not quite out of the woods yet. Unfortunately, the extreme vulnerability to heavy rainfall of both the landscape and the population is going to be a long lasting legacy of the earthquake.

Typhoon Megi and the Philippines

2010-10-19T08:10:00.001+01:00

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

At the time of landfall this was a true super typhoon. Even in its current weakened state it is generating gusts of up to 195 kph. Inevitably, it has brought very heavy rainfall to the north of the Philippines, although to date there is no news of any large landslide accidents. However, at the moment the storm appears to be stalled just offshore (see PAGASA satellite image below), which is the scenario that often leads to prolonged intense local rainfall and thus significant slope problems.

Tropical Storm Risk are forecasting that this typhoon will track northwestwards and will strengthen to landfall to the west of Hong Kong. If this forecast is correct then there must be the potential for substantial landslide and flood occurrence in southern China in the next few days.

5th Canadian Conference on Geotechnique and Natural Hazards

2010-10-19T07:55:00.000+01:00

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:
http://www.geohazards5.ca/program.php?lang=en

With sesveral landslide sessions at the AGU Fall meeting in December, multiple 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!

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

2010-10-17T20:04:00.001+01:00

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

Round up of landslide stories and events for the last week

2010-10-16T16:06:00.002+01:00

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

Thanks once again to Peter Diehl, the prize for bizarre landslide event of the week goes to a very strange event at a former lignite mine near Hoyerswerda, Saxony, Germany on Wednesday. The slide appears to be similar to a quick clay slide, but on a very large scale - the surface area affected is 110 hectares. This event did not seem to make the English language news, but a German report can be found here. Fortunately no-one was killed, but 84 sheep were lost. The best images of the event are at this page - also in German. Click on the "Fotogalerian" link in the box on the left side, half way down the page. The two images here are from that source.

The red box shows some trucks caught in the landslide.

2. An interesting rockfall in Wyoming
Thanks to Lisa Denke for this one. There is an terrific gallery of images of a rockfall event in Wyoming on Interstate 80, also on Wednesday, available at the trib.com site. According to this article, the cloud of dust generated by the rockfall (see below), which came from a bluff known as the Palisades, reduced visibility to the extent that several motor collisions occurred, injuring four people.

3. Climate change and landslide story of the week
Regular readers will know that there is no doubt in my mind about the reality of the link between human releases of greenhouse gases and increases in the global temperature. However, I continue to greatly frustrated by some aspects of the way that this issue is handled. The latest example is a story being run by a number of media outlets, such as this one (in New Scientist, which surprises me), under the headline "A warming world could leave cities flattened". The basis of this is a perfectly respectable paper in Global and Planetary Change that looks at a very large volcanic flank collapse in Chile. From this is spun a surprisingly strident headline on an issue that is not even mentioned in the paper. Indeed the words "city", "cities" and "urban" do not appear anywhere in the paper, as far as I can see.

hmmmmmm!!!!

Some statistics on disasters worldwide

2010-10-14T07:59:00.000+01:00

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

Important news about this blog

2010-10-13T06:44:00.000+01:00

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.

Slope Stability 2011

2010-10-12T07:44:00.000+01:00

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

http://www.slopestability2011.ca/

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.

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

2010-10-11T07:17:00.001+01:00

The index.hu 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:

As expected, the image shows that the main block shown has moved to the right and subsided. However, it is less clear to me as to whether at the remainder of the dam to the breach has actually moved. However, newspaper reports suggest that this wall is now considered to be so unstable that it is likely to collapse. Attempts are underway to build a bund to contain the resultant spill.

Meanwhile, there is now some post-event Google Earth imagery available for download here. Whilst the resolution is not really good enough to see exactly what has happened at the dam itself, it rather clearly shows the flowpath of the debris:

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

2010-10-10T07:41:00.001+01:00

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:

This is the damaged (cracked) section of the north side of the dam. Zooming into the cracks on the top of the dam shows this:

The pipeline running across the top of the dam is clear. Note that where it crosses the main (left side) crack the pipeline has been detached from the supports, which have moved forwards and downwards. A little further to the right the pipe has ruptured, and tailings have spilt across the dam surface. Thus, it is clear that the dam has moved forward and subsided at this location, which further supports (though does not confirm) the suggestion that the dam collapse was associated with failure of its foundations.

Interestingly, some suggestions are also emerging that this section of the dam had been leaking ahead of the collapse. WWF has an aerial image taken in June this June of the dam that appears to show a small leak:

However, this should be treated with some caution as there may be other explanations for this apparent spill of tailings on the downstream side of the dam. Finally, there is a gallery of image here that shows the state of the dam in 2005. These two give a pretty good idea of the general state of affairs at the dam:

Comments?

New aerial images of the Ajkai Timfoldgyar tailings dam site

2010-10-09T07:11:00.000+01:00

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.

September 2010 fatal landslide statistics

2010-10-08T07:18:00.000+01:00

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:

Number of landslide events that caused one or more fatalities worldwide: 36
Number of people killed by landslides: 377

This compares with the following average number for 2002-2009:

Number of landslide events that caused one or more fatalities worldwide: 37.4
Number of people killed by landslides:770
So, September has finally reversed the trend seen for most of the previous months of this year to date in which landslide occurrence has been much higher than average. This graph shows the cumulative total number of recorded landslides that have caused one or more fatalities. It includes the cumulative total number of recorded fatality-inducing landslides for 2003 (which had the lowest total of any year on the database), 2009 (the previous record year), 2010 to the end of September, and the average for 2003-2009. Even though September was not exceptional, the cumulative total for the year remains exceptional:

With the monsoon now weakening and the northern hemisphere tropical cyclone season drawing to a close, the peak period of landslides worldwide is now coming to an end. However, typically the occurrence of landslides in Central and South America, and in SE Asia, starts to increase in late October.

One other point to note about September 2010. This month has seen two landslides in which there were initially very high estimates that were subsequently (rather quietly) reduced. The highest profile was the 27th September landslide at Santa Maria Tlahuitoltepec in Oaxaca in Mexico, which was initially estimated to have killed hundreds, and possibly thousands. The final death toll was eleven people. The second case is the remarkable landslide at Giraldo in Colombia, that was caught on video:

In this case the initial estimates were that 30 people were killed. This has now been reduced to 10 people.

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

2010-10-07T07:54:00.001+01:00

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 wise-uranium.org 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.

Interesting images of the Ajkai Timfoldgyar tailings dam accident in Hungary

2010-10-06T20:37:00.002+01:00

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:

http://galeria.index.hu/belfold/2010/10/05/legifelvetelek_az_atszakadt_gatrol/

In terms of the failure that caused this dreadful event, the best images are these two below. Take a little time to appreciate the scale of this - the first image has some machines in the foreground that provide perspective. The first image shows the breach itself:

The really revealing image is this one - the breach is to the right of the image. It suggests that this block had moved off its foundation and that the section close to the reach had moved forward. Note the material that has come through the resultant crack:

The fact that the final failure occurred in a right angled bend in the dam wall is very interesting, as this is a point of stress concentration. If I were the team investigating this failure I'd be very interested to see the calculations of uplift force on the base of the dam.

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

2010-10-05T21:25:00.002+01:00

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:

The failure appears to have occurred in the corner of the embankment, as shown in this Google Earth image:

I cannot quite work out the internal structure of the embankment from the image - it looks rather peculiar, but I'll reserve judgement until better information is available.

Meanwhile, the mainstream media has finally cottoned onto the story, which now appears near to the top of the BBC News front page. The BBC article has a good image of the impact of the material downhill from the breach, paired with a map of the location:

The article also notes that there are now real concerns about this sludge causing an environmental disaster when and it it enters the river system; and that four people died and six remain missing.

Tailings landslide in Hungary and a dam crisis in Vietnam

2010-10-05T08:06:00.002+01:00

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.

The Google Earth imagery of this area shows the origin if the accident rather clearly as the red bauxite ore in the lagoon is fairly obvious. This location is confirmed by an article on NOL.

Interestingly, a slightly older Google Earth image is also available (this is from March 2008, whereas the one above is from October that year). This image appears to show a rather less full lagoon:

Reading Hungarian news reports is not my strong point, but MNO has a detailed article on the event. This suggests that three people have been killed and 113 injured, of which 73 people required hospital treatment. Unfortunately, bauxite ore was is a very nasty material, causing alkali burns, so some of the injuries could be very serious. The residue of the disaster is pretty foul as the MNO article illustrates:

I haven't yet seen any images of the embankment failure that caused this event - I expect that these will appear online today. I will post again when these are available.

Meanwhile, in Vietnam there are reports of a rather different crisis. Vietnam Net Bridge reports that 20,000 people have been evacuated from below the Ho Ho Dam in Huong Khe district of Ha Tinh province. The reports suggest that during the ongoing heavy rainfall the spillway door jammed closed, causing the lake to overtop the dam. Although the door has now been fixed, concerns remain that the dam may collapse.

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

2010-10-03T07:08:00.001+01:00

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:

If you look carefully you can see the brown mud stains and splatters up the wall that show the height of the flood at its height. The river bed is continuing to aggrade (increase in elevation due to sediment accumulation) at this point, slowly burying the ruins.

Upstream the village itself shows clear signs of the damage to houses and other structures from the earthquake shaking:

In some cases repairs to the buildings had started before the debris flow activity started:

However, the ongoing landslide activity, and resultant changes to the riverbed, are proving to be devastating, with high levels of hazard and repeated burial of buildings:

The effect is to hugely reduce the rate at which reconstruction can occur, and to greatly increase poverty as the the people have lost both their assets and their most productive farmland. As a result, two years on they are still living in the emergency huts constructed after the earthquake, which are now becoming fossilised into permanent structures, albeit of a poor quality:

Unfortunately, these problems are likely to persevere long into the future, leaving the population with serious challenges for decades to come. Unfortunately, a key impact is likely to be to drive the young into urban areas, leaving rural areas populated by elderly people living in a state of great poverty.

Beichuan town - the old and the new

2010-10-02T06:30:00.000+01:00

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.

Images of yesterday's landslide-induced train incidents

2010-09-26T01:49:00.000+01:00

First, an apology in advance. I am just en route to Chengdu in China, where I will stay until Saturday. Whilst this provides an opportunity to return to Beichuan, which will be very interesting in the context of the rainfall-induced landslides this summer, it presents some other challenges. The most serious of these is that Blogger is blocked by the Great Firewall of China, so I will not be able to access it to make posts. So if it all goes quiet for the next few days, please accept my apologies. I should be able to post again on Saturday.

Anyway, in the meantime thanks to various people for highlighting photos of the various landslide-related train incidents over the last 48 hours. It now appears that New Zealand on its own experienced two incidents; in addition to the one at Manawatu Gorge there was also an incident at Taumaranui. There were no injuries in either case.

In terms of the Manawatu Gorge incident, stuff.co.nz has a pretty spectacular set of images:

Meanwhile, there are also some images of the incident in India available on The Hindu website here. Unfortunately, at the time of writing their site is down, but I managed to access it last night. Hopefully you will have more luck!

Three landslide-induced railway incidents in a single day

2010-09-25T01:40:00.000+01:00

News today of three different incidents from around the world:
1. New Zealand
NZ Herald reports that a milk train hit a landslide in Manawatu Gorge. Fortunately there were no injuries, or even a need to cry over spilt milk...

2. India
Bangalore Mirror reports that three coaches of the Thiruvananthapuram-Mangalore Express train were buried by a landslide in a narrow cutting at Mulunthurthy. Three people were injured, plus there were some minor injuries during the evacuation.

3. Canada
Various Canadian newspapers report that there was a serious landslide-induced derailment of a freight train at St-Lazare in western Quebec. The accident trapped the injured train crew in their cab, requiring that they were rescued by firefighters. Heavy rainfall was reported to be the trigger. The images of the site, from the Montreal Gazette, are impressive:

Landslides represent an important risk to railways in upland areas, and where extensive earthworks have been used. Railway companies expend huge amounts of resource mitigating the threat, usually with success. Incidents are quite rare, but previous examples described on this site include:
May 2010: 19 killed when a train struck a landslide in China;
April 2010: Nine people killed when a train was struck by a landslide in northern Italy;
July 2009: Four people killed when a train struck a landslide from a cutting in China;
Dec 2008: A train was struck by a flowslide formed from power station ash in Tennessee, USA;

Remarkable NASA imagery of catastrophic flooding around Manchhar Lake in Pakistan

2010-09-24T01:49:00.001+01:00

NASA have provided the most dramatic evidence yet of the catastrophic floods that are occurring around Manchhar (Manchar) Lake in Pakistan (see my post yesterday on this issue). This image was captured by the ALI instrument on 18th September:

Compare this with an image taken of the same area just three days earlier:

Or the Google Earth image of the same area, which was collected in May this year:

Geo-TV, an independent TV station in Pakistan, reports that some of the breaches that are causing these floods are now 1 km wide, whilst NTDTV notes that the number of people displaced by this most recent component of the floods may be as high as 250,000.

The breaches have allowed the water level in the main body of the lake to fall slightly, bringing some relief elsewhere, but with new areas continuing to experience flooding that is not cause for much overall cheer.

Pakistan flood update

2010-09-23T01:52:00.000+01:00

The Pakistan flood crisis drags slowly on, and probably has at least a month to go before the waters fully recede. Although the news coverage of the event is now little more than a drumbeat in the background, huge numbers of people are still being affected for the first time by this event. The current crisis is focused on Mancchar Lake, which has been the destination of the waters that have travelled down the "ghost" parallel water course to the west of the main Indus channel, as shown very clearly by this NASA image:

The key iprblem at Manchhar has been that the waterways that allow the lake to drain are inadequate for the task, which has allowed the lake level to rise, causing new flood damage. The reasons for this are clear from the following Google Earth image, taken before the flood:

In recent years the lake has suffered from inadequate inflows and serious salinity problems, to the extent that last year water was diverted into the lake from the Indus to improve water quality. This of course shows that the need to have adequate drainage to allow large inflows to be released has not been a pressing issue of late. Thus, the two channels lining the lake to the Indus are too small to deal with the inflow:

In order to drain the excess water in the lake, the levees have been breached in eight places (I am unsure whether these breaches are natural or artificial), but the water level is reportedly still rising, and according to the UN 100,000 people have been displaced in 215 villages.

Meanwhile the World Food Program have produced a report, available online here, that documents the scale of the impacts of the floods to date. There are a number of useful aspects of this report, not least the following map that shows the extent of the floods:

Note that the data notes that there is no data for the northern regions, which of course were also very badly affected. The upshot is that the statistics in the report under-represent the true impacts. Nonetheless the statistics are eye-watering:

14.1 million people directly affected
392,786 damaged houses.
728,192 destroyed houses
7,600 destroyed schools
436 health facilities damaged or destroyed
Overall production loss of sugar cane, paddy and cotton is estimated to be 13.3 million tonnes
2 million hectares of standing crops were either lost or damaged.
1.2 million head of livestock (excluding poultry) lost
14 million livestock are at risk due to fodder shortages and heightened risk of disease.

Of course it is important to consider these impacts in the context of the pre-existing situation in Pakistan. This map, also from the WFP report, shows the state of food security in most of Pakistan before the floods. Much of northern and western Pakistan were considered to be extremely food insecure. The central swathe of Pakistan most seriously affected by the floods was in a better (though in most cases not ideal) food security state:

The effect of these flood will be to plunge a large part of Pakistan into a state of extreme food insecurity through the coming winter, at a time when houses, infrastructure and health facilities are seriously compromised.

Tangjiashan again - and a possible new Chinese flowslide

2010-09-21T23:50:00.000+01:00

Back in 2008 I dedicated a great deal of space on this blog to the extraordinary efforts by the Chinese Army to draining the landslide lake at Tangjiashan, just above the town of Beichuan, which was created by the May 2008 Wenchuan Earthquake.

These efforts were ultimately successful, but in my visit to the site in Spring 2009 it was clear that a threat remained at the site in the form of another block of material that was showing signs of deformation. Over the last few days this area has received very high levels of rainfall. Yesterday, Xinhua reported that a 300,000 cubic metre block has detached from the scarp above the barrier, and blocked the river to a depth of 10 metres:

"More than 6,200 residents were relocated Tuesday as torrential rains pounded Beichuan Qiang Autonomous County in southwest China's Sichuan Province, local authorities said Tuesday...Some 300,000 cubic meters of debris brought by the landslide caused a dam, blocking the lake's outlet. The dam's lowest point is 10 meters higher than the present water level, the statement said. Debris still continue to come down from the hills, and if there were more rains, then the lake level would further rise, threatening the lives of people in nearby townships.The rains had disrupted the normal life of 58,000 local residents in the county, causing huge economic losses, the statement said."

China is well-versed in dealing with these hazards, but given the magnitude of the destruction in the Beichuan area, such events must cause great heart-ache.

It is clear that the elevated level of landslide activity in the aftermath of the landslide is a major issue. I am travelling to Chengdu on Sunday, so will see whether I can ascertain more information about these issues.

Meanwhile, Bloomberg reports a probable flowslide failure in a tin mine in Guangdong yesterday:

Zijin Mining Group Co. said a dam built to hold tin-mining waste collapsed in China’s Guangdong province following torrential rain, less than three months after one of its copper mines leaked toxic waste into a river.About 60 centimeters (24 inches) of rain from Typhoon Fanapi and mud and rock slides triggered the accident at the company’s Yinyan tin mine at about 10 a.m. local time today, Shanghang, Fujian province-based Zijin said in a statement.

China has been impacted by a series of these events in recent years, including one that caused multiple fatalities in 2008. There appears to be a strong need to improve the safety of these facilities before another major accident occurs.

Gifts and Perils of Landslides

2010-09-21T02:32:00.000+01:00

Ken Hewitt has written a wonderful article for Scientific American entitled "Gifts and Perils of Landslides", in which he examines the inter-relationship between the development of society and the occurrence of landslides in the Upper Indus valleys. Ken is the guru of high mountain landslides in Pakistan, having spent many field seasons mapping rock avalanche deposits in the remote upper valleys of the Hindu Kush. The article is available online at the following link:

http://www.americanscientist.org/issues/feature/2010/5/gifts-and-perils-of-landslides

His key point is that these giant landslides create both destruction and benefits to humans in this very rugged topography, the latter because they create terrain that is fertile (e.g. on lake beds formed behind landslide dams) and less steep.

The piece will be accompanied in due course by a slideshow, which will be online here. This is not yet available.

Meanwhile, the Pamir Times has an image of restarted works on the Attabad landslide, the aim of which is to widen and then, I understand, to deepen the spillway:

Landslides in Art Part 7 - Jennifer Williams

2010-09-20T03:05:00.002+01:00

Regular readers will know that I occasionally highlight a piece of art featuring landslides. This is usually a piece of visual art (such as this and this), but occasionally it is a song or even an installation. This time I thought I'd feature a piece of art by the American artist Jennifer Williams, who paints environmentally-orientated pieces using acrylic on birch panels. Jennifer works mostly in the Pacific Northwest, where both the landscape and the sky is large and colourful. This is reflected in her portfolio of work, which resonates strongly through its depictions of the landscape of hazards.

I'd like to highlight here two pieces. First there is a painting called lahar, created as part of a portfolio encompassing the natural regeneration of the Mount St Helens area:

Second, and for me more strikingly, is a piece entitled simply "Landslide", painted in 2008, and visible through the Waterworks Gallery website:

To me this captures the chaos and ruin of the catastrophic earthflows we see in the Himalayas and other high mountain environments during heavy rainfall. Amazing stuff.

Earthquake damage in Christchurch - an ironic billboard

2010-09-19T06:45:00.001+01:00

This billboard, which predates the Darfield earthquake, was attached to a building in the Central Business District of Christchurch in New Zealand:

Do you think this is what they had in mind when they described the "open plan office with balcony access" and "cool funky office environment"?:

Images of the Darfield (Canterbury) earthquake fault rupture

2010-09-18T08:27:00.000+01:00

Yesterday I was exceptionally fortunate to be able to spend the morning looking at the surface expression of the fault responsible for the Darfield earthquake, which hit the Canterbury plains area of New Zealand a fortnight ago. I was kindly guided around by Russ Van Dissen of GNS Science, and the visit was organised by Chris Massey, also of GNS - so many thanks to them. This GNS map shows the surface expression of the fault across the Canterbury Plain:

These pictures will work from east to west.

The east-most expression of the fault occurs close to the town of Rolleston, where a railway track crossed the fault. The rails have been repaired, but the kink in the formerly straight railway track is fairly obvious.

Just around the corner a road crosses the fault as well. Here the damage, again to the formerly straight road, is unrepaired as the fault is expressed as a broad deformation zone accommodating about 60 cm of movement:

If you are struggling to see the feature, remember that the road stretching into the distance (not the bit at the very bottom of the picture) was straight before the earthquake. You should be able to see that from the middle of the image the road has been shifted to the right. In this area there is little evident vertical change, bearing in mind that the surface was not perfectly flat before the earthquake.

A few kilometres to the west there is another formerly-straight road crossing the fault. Here we see a little more lateral movement - actually about a metre. Again, there is no vertical movement. The movement is evident in this image - look at the alignment of the edge of the road:

Lets now jump a few more kilometres to the west, where things start to get really interesting! Another formerly straight road is our indicator of strain - but now it is becoming difficult to believe that this happened in a single 30 second event (I can assure you it did):

Note here the highway people have resurfaced the road, so the original cracks are no longer visible. There is a ditch running down the side of the road that also shows the deformation rather clearly:

The movement here is about 3 metres or so. Again there is little evidence of vertical deformation.

The farmer at this site very kindly allowed us to enter his field (please do not do this without permission), where the array of cracks, and associated deformation, is astonishing. GNS have an aerial view of the field here; below is the ground view:

The movement of the fault is evident in the power lines that cross the fault here. The movement of the fault has put the cables under tension, meaning that the insulators (the pieces that join the cable to the pylon) are no longer hanging vertically:

A few more kilometres to the west and we are into the maximum displacement area. Here we see over 3 metres of horizontal deformation and about 1.5 metre vertically. This is the view from the hanging wall side - the drop down onto the footwall, and the lateral motion should be evident:

The picture below was taken on the footwall side looking back towards the fault - note the horizontal motion (the road has been patched up) and the vertical change. Remember that this was a straight road across a flat plain before the earthquake:

The maximum deformation is recorded a little to the west again, where a road is offset by almost its entire width, indicating movement of about 4 metres. There is some vertical deformation too, but this appears to be more of a ground roll than a true vertical movement of the hanging wall block:

Our last site is at the western end of the fault trace. Here the surface expression of the fault is reducing, leaving a small step in the road that is quite hard to see. The best evidence is from the power cables, some of which are now very tight (those on the upper right), whilst others are very slack (those linking to the pole on the far right). Note how the tension cable supporting the pole on the left has also gone loose - this would have been taut before the earthquake:

It is at this point, almost perfectly on the fault, that the highest accelerations were measured.

I hope this gives a useful overview of the fault. I am happy to answer any questions, though Geonet and GNS Science are the experts.

Comments welcome

Zhouqu landslide - NASA satellite image

2010-09-16T07:28:00.001+01:00

NASA have somehow managed to find a gap in the clouds to collect a satellite image of the Zhouqu landslide site. Readers at the time of the landslide last month will remember that I was wondering about the source of the slides. Although this image does not give a full answer, it gets us a part of the way there:

A zoom into the affected area yields this:

The slides (note the smaller one to the right of the main event) clearly originated as a series of smaller slips on the walls and headwaters of the upstream catchments. These appear to have coalesced to form the main events. This is consistent with processes observed elsewhere during periods of exceptional rainfall.

Meanwhile, I am now in Christchurch in New Zealand, site of the earthquake of 12 days ago. Every 30 minutes or so my chair shakes as an aftershock rattles the area, which is a very surreal experience.

Road failure video from Thailand

2010-09-14T21:35:00.000+01:00

Thanks to my former student Kurtis Garbutt for the heads up on this one. The video below shows the progressive development of a road in Thailand. I suspect that this initiated as a culvert failure, with multiple collapses due to undercutting:

The final frames of the video show an overview of the site. Check out where the people are standing!

As an aside, Kurtis also runs a very interesting blog on natural hazards - take a look. It is a very useful resource with a scope that goes way beyond my site.

Pakistan floods - the extraordinary duration of the elevated water levels

2010-09-11T23:19:00.001+01:00

The floods in Pakistan may have faded from the headlines in Europe, but unfortunately the impact continues, even though the rainfall events that caused them occurred more than a month ago. The most dramatic illustration of this is a set of satellite images collected by NASA using the MODIS instrument.

This is an image of the area around Sukkur taken on 7th July, before the rainfall event that initiated the disaster:

By way of comparison, this image was taken on 7th September, showing the same area:

Two things to note. First the extensive flooding along the line of the main part of the Indus remains. This may well be an indication that water is draining very slowly from behind the broken levees, which are now serving to keep water in despite their failure to keep the water out in the initial event. Such problems with broken levees are common. Second, note the parallel course of the Indus that has been created, where the flooding is much more intense. I assume that this is the river occupying one of its old drainage paths. The problem here may be that the downstream end of this huge (check out the scale bar on the imagery) new watercourse is Mancchar Lake. This is an artificial lake, created in the 1930s, with a range of existing environmental problems. The lake appears to be connected to the main Indus River by just two small canals (see Google Earth image below):

This limited drainage path is may cause the floods to drain very slowly, prolonging the agony for those affected. The flood waters must now be highly polluted, increasing the potential for health problems for the affected population.

Ruapehu lahar information

2010-09-10T21:05:00.000+01:00

One of the many highlights of the splendid IAEG Congress in Auckland this week was a talk by GNS geologist Chris Massey on the 18th March 2007 lahar at Mount Ruapehu on North Island. The lahar occurred as a result of the failure of a tephra wall holding back the crater lake at the summit, and is shown by this NASA image:

The potential for a lahar had been anticipated and the site was intensively monitored with real time instruments such as water level sensors and geophones; with two web cams; and with periodic surveys using a terrestrial laser scanner. An emergency plan was in place and worked well. The need for caution was undeniable - on 24th December 1954 a lahar from the same site demolished a railway bridge at Tangiwai, killing 151 people on a train that tried to cross a bridge that had been destroyed by the lahar.

The event has been written up in a paper (Massey et al. 2010), and there is a spectacular set of images of the event captured by the web cam available here (NB it took me a while to get my eye into these images).

An interesting aspect of this event is that one can examine just how good the natural hazard science community is at assessing hazard. There is a New Zealand Civil Defence report, written in 2002, about the threat of a lahar at Ruapehu online here.

Reference
Massey, C., Manville, V., Hancox, G., Keys, H., Lawrence, C., and McSaveney, M. 2010. Out-burst flood (lahar) triggered by retrogressive landsliding, 18 March 2007 at Mt Ruapehu, New Zealand—a successful early warning. Landslides 7 (3),303-315, DOI: 10.1007/s10346-009-0180-5.

Italian debris flood video

2010-09-10T06:42:00.002+01:00

Thanks to Ivan Montanari for highlighting this one. Youtube has an extraordinary video of a debris flood that appears to have occurred yesterday at Atrani on the Amalfi Coast in Italy:

The video makes a slowish start, so keep watching. This is the first debris flow of cars that I have seen on video...! This is a Google Earth perspective image of Atrani:

I guess it is not hard to see how very heavy rainfall, or another hydrological event in the catchment, can lead to such an event.

A round up of intersting events and documents in the world of landslides and slopes

2010-09-09T20:41:00.000+01:00

1. Please vote for a slope monitoring project
One of the recurrent themes of the IAEH Congress is the growing importance of slope monitoring techniques to provide warning of the development of failure. One of the most exciting projects is the ALARMS project, led by Prof. Neil Dixon at Loughborough University, which is developing techniques that use acoustic emissions to monitor slope movements. The project has been entered into an Enterprise competition at Loughborough University, which will be decided by a free vote. So, please can you visit this page: http://www.lboro.ac.uk/business/enterprise-awards/ and vote for the Alarms project. It would be a very worthy winner of the prize.

2. Manual on Engineering Geological Practice in Hong Kong
On behalf of the Hong Kong Geotechnical Engineering Office, AECOM have produced a new manual on engineering geological practice in Hong Kong. Unsurprisingly, it has a strong slopes and landslide component, and it is relevant in areas outside of Hong Kong itself. This can be downloaded as a pdf for free here. I recommend it - I think that it will become a very useful guide and reference text.

3. 11th Symposium on Landslides (ISL)
The big four yearly slopes event is the ISL, which was last held in Xian, China. The next event is in June 2012, and will be held in Banff, Alberta Canada. This should be a fantastic event in a wonderful location. The meeting now has a website, and the call for abstracts has been released, with submissions due by 15th April 2011. Get writing!

4. Slope Stability 2011
In September 2011, Canada will also host a conference on rock slope stability, with a strong emphasis on the mining industry. This event, which will be held in Vancouver, will be a great opportunity for academics and practitioners to interact. The site has a website, and again a call for abstracts is out, with a deadline of 7th January 2011.

IAEG presentation and paper on Attabad

2010-09-09T04:03:00.001+01:00

Today I presented an invited paper at the 11th Congress of the IAEG in Auckland, New Zealand on the topic of landslide hazards along the Himalayan Arc. This paper starts by looking at global and regional landslide hazard before presenting the state of play at Attabad. As usual, I have uploaded the PowerPoint file to Authorstream, such that you should be able to both view and download it below:

10_09 IAEG petley v2

See more presentations by Dr_Dave | Upload your own PowerPoint presentations

The written paper has been published in the conference proceedings. I do not have a pdf of the actual printed version but I do have one of the final manuscript. I am working on putting that online, so watch this space.

A pdf of the paper itself is available here:
http://www.mediafire.com/file/w34v38zb4uvzcj4/10_06%20Petley%20invited%20final.pdf

Note that this paper contains a map of global landslide losses in terms of fatalities and some data both for global losses and for those in the Himalaya.

Note that the typeset format is slightly different from that of the actual published paper, but the content is the same. The reference to the paper is:
Petley, D.N., Rosser, N.J., Karim, D., Wali, S., Ali, N., Nasab, N. and Shaban, K. 2010. Non-seismic landslide hazards along the Himlayan Arc. In: Williams, A.L., Pinches, G.M., Chin, C.Y., McMorran, T.J. and Massey, C.I. (eds) Geologically Active. CRC Press, London, pp. 143-154.

Updated: The New Zealand earthquake

2010-09-03T21:36:00.001+01:00

Bizarrely, I am currently sitting in the QANTAS lounge at Sydney Airport waiting for a flight to New Zealand, where the IAEG Congress starts on Monday. The theme of the conference is "Geologically Active"...

So, what do we know about the earthquake so far. The best source of information is the Geonet site - http://www.geonet.org.nz/ - which puts seismic data online in real time. They are reporting that the earthquake occurred at 4:35 am local time 30 km west of Christchurch at a depth of (now updated to) 10 km. The reported magnitude is (now updated to) 7.1 - USGS is reporting 7.0, but this is probably a moment magnitude. This is the isoseismal map from Geonet:

This suggests that some damage in the Christchurch area is likely, which seems to be confirmed by the initial news reports. Hopefully the timing of the earthquake, and the high level of preparation for earthquakes in New Zealand, will mean that casualties will be light and damage manageable. Perhaps the most interesting data at this stage is the map of locations in which people have reported they felt the earthquake. This looks like this at the time of writing. The dark orange dots represent an intensity sufficiently large to cause significant damage:

GEONET shake map


	There are no reports of landslides as yet, but given the proximity of the Southern Alps some landslides are likely:



	More later.

August fatal landslide data

2010-09-03T04:46:00.001+01:00

The end of the month marks the point at which I post the accumulated totals for fatal landslides, based upon the global fatal landslide database that I maintain. The raw figures for August are stark. The total number of fatal landslides recorded in the month was 71, resulting in 2,740 fatalities. This total is of course dominated by the Zhouqu landslide in China, which is reported to have resulted in 1,765 deaths. (Click on read more to access the remainder of this post).

These totals continue the exceptional trend of landslide occurrence in 2010. The average number of recorded fatality-inducing landslides in August in the period 2002-2009 is 46.7, resulting in an average of 348.3 deaths.

This graph illustrates the magnitude of the anomaly for 2010 to date. This shows the cumulative total number of recorded fatality-inducing landslides for 2003 (which had the lowest total of any year on the database), 2009 (the previous record year), 2010 to the end of August, and the average for 2003-2009. There is no doubt that 2010 is exceptional:

It is interesting that these totals have been recorded in a year that to date has had exceptionally low levels of tropical cyclone activity - indeed Northern Hemisphere tropical cyclone energy release remains at the lowest level for 30 years. When they occur, landfalling NW Pacific tropical cyclones (typhoons) have a major impact upon landslide occurrence. It is notable in particular that the Philippines and the Caribbean islands (especially Haiti) have been spared substantial tropical cyclone events to date this year. Given that there are strong signs that tropical cyclone activity is currently increasing in both the N. Atlantic and the Pacific, the next month will be very interesting.

Of course, the root cause of the exceptional occurrence of recorded landslides in August has been the intensity and volume of rainfall associated with the summer monsoon, primarily in China and Pakistan, and to a lesser extent Nepal. The monsoon should start to weaken during September, but more landslides are likely in the interim given the near-saturated state of the ground.

Another large landslide in China

2010-09-02T14:01:00.000+01:00

China has today suffered another large landslide event. Xinhua reports that a slide happened at 10:20 pm on Wednesday in the village of Wama in Longyang District, Yunnan, leaving 8 people dead and 40 missing. Xinhua have this image of the slide:

As far as I can tell, this is the location:

Unfortunately the Google Earth image for this area is poor, but there is a report on a small hydro-electric scheme at this village available online here. I should add that I am not suggesting that the HEP scheme was responsible for the slide. This article on recent permission for logging in the area is also interesting.

The latest NASA image of Attabad

2010-09-01T07:50:00.000+01:00

NASA have released another spectacular satellite image of the Attabad dam and lake. In the article they focus on the upstream end of the lake:

The article states that the water level can be seen to have dropped as the area upstream of Hussaini is no longer inundated. Now there is some evidence that the water level has dropped a little - the Pamir Times reports 12 feet (4 metres), although this may well be a downslope distance rather than a vertical fall. As inflow decreases the water level should decline until the outflow balances this amount. The Pamir Times article above also alludes to operations on the spillway, though it is unclear as to whether these have actually started. I think that it is more likely that the apparent drop in the imagery is actually due to sedimentation in the river channel. This is supported by a close look at Hassaini itself, which shows no signs of a drop in water level.

To me the most interesting aspect of this new image lies in the main part of the lake:

This is a comparison of the two most recent images of the landslide scar, dam and spillway area. The first was collected on 7th July. Note that it is partially obscured by dust:

Whilst the second is the most recent image, collected on 23rd August:

The key thing to note is that the spillway has evolved considerably - it has widened and become more sinuous. There is also some apparent change in the water flow upstream end of the channel, which appears to be more turbulent now. This could be due to a change in the volume of flow. Finally, note that there also appears to be a couple of dust clouds in the upper part of the scarp area, suggesting that this is still evolving.

All of this means that system has not yet reached an equilibrium state, and thus remains a threat. Fortunately though as winter approaches the risk of a rapid collapse is reducing, although unfortunately not to residual levels.

Catching up - recent landslide events

2010-08-31T09:22:00.002+01:00

The next few posts will be an attempt to catch up on the things that I missed whilst on vacation in Switzerland last week. Thanks to the many people who have tipped me off about landslide events. I will cover Pakistan in another post.

1. A large flow in Austria
Thanks to Martin Springer for highlighting this one. On Saturday 21st August a severe storm triggered a 100,000 cubic metre flow in the Karwendel Nature Reserve. Fortunately no-one was killed, but a dozen cars are trapped in a car park. It will take two months to clear the debris. There is a short video of the deposit and further details about the landslide (in German) here.

Read more by clicking below:

2. The power of a mudflow illustrated by an articulated truck in California
Thanks to Lisa Denke for this one. A large storm in eastern California on Thursday last week triggered a mudflow in the Owens Valley in eastern California. An articulated truck (known as a tractor trailer in the US) was caught in the path. There is a short but useful video of the event in this news report:

3.An excavator in Gilgit-Baltistan
Accompanying the video above is an extraordinary image of the aftermath of the rains in Pakistan, courtesy of the Pamir Times:

I am reminded of the old "how does the driver of a snowplough get to work?" line.

4. Devastating landslides in Turkey
Also on Thursday last week, heavy rainfall triggered landslides in the town of Gundogdu, in Rize Province in Turkey, killing 12 people. The image below is taken from this news report:

5. The typhoon season has now got started
Finally, the very slow start to the Pacific typhoon season has now come to an end, with a series of storms developing at the moment. The three storms currently active all have the potential to cause landslides (image from Tropical Storm Risk):

Lionrock and Namthuen could both bring very heavy rainfall to southern China as they track inland over the next couple of days. Meanwhile, the forecast track of Typhoon Kompasu suggests that this very intense typhoon could bring substantial amounts of rainfall to the Korean peninsular. North Korean in particular is very vulnerable to the effects of heavy rainfall due to the extensive deforestation endemic in that country. The potential impacts of this storm are serious, although note that there is considerable uncertainty in track forecasts.

Amazing new rockfall video from Yosemite

2010-08-27T20:23:00.001+01:00

Thanks to Greg Stock for bringing this one to my attention. Yosemite National Park have produced a video providing information for visitors about the hazards associated with rockfalls. It includes an extraordinary piece of footage - captured by a visitor to the park - of a rockfall detaching from the cliff, fragmenting on impact on the the slope, and then travelling down the talus slope. The video of the detachment event is fantastic - I have never seen anything as good. However, the rest of the video is great as well, and will be very valuable to those trying to provide improved awareness rockfalls in many environments. The video should be viewable below (click on read more to see the rest of the post):

Or you can view it here: http://www.youtube.com/watch?v=H0YhlqP1BgE

Hunza debris flow video

2010-08-25T07:01:00.000+01:00

You probably guessed that I am on holiday this week (normal service will be resumed at the weekend), but I thought I'd quickly post this new debris flow video from Hunza in Pakistan. The interesting but starts at about 1 minute 15 seconds:

New pictures of Attabad

2010-08-17T20:43:00.001+01:00

Many thanks to David Butz, who is a Professor of Human Geography at Brock University in Canada, for sending to me a set of photographs of the situation at Attabad. David was there about eleven days ago, when the boat service was still running (it has now ceased due to a lack of fuel). David has kindly allowed me to post some pictures here - note however that he retains ownership and copyright of them.

The dam from from downstream (click on "read more" to get the remainder of the post):

A close up of the downstream part of the spillway. Note the very large boulder:

The upper part of the spillway, the point at which the flow rate increases:

The landslide mass from the upstream side:

The towering landscape and the heavily overloaded boats that ply the lake:

Many of the displaced people are still located in very hazardous locations:

And to finish, the best image that I have seen to date that is able to show the size of the landslide. Remember that the lake is 120 metres deep:

Pakistan flood update: the Kirthar Canal

2010-08-17T08:59:00.001+01:00

The floods in Pakistan continue to extend to new areas, increasing the magnitude of the impact on a daily basis. The PakMet hydrographs continue to show increasing flow levels. At Guddu the discharge is still rising, and is now close to the peak level reached in the first flood wave (click on "read more" to reveal the rest of this post):

Meanwhile, as expected serious problems are developing in the area of (but so far not on) the Guddu Barrage, where the discharge is also increasing:

It appears that the second flood wave has not really reached Sukkur as yet. However, Dawn this morning reports that: "...residents of Qubo Saeed Khan town and over 100 villages in Qambar-Shahdadkot district were asked to leave their homes on Monday after a powerful current of floodwaters gushing from Garhi Khairo and overtopping the Khirthar canal smashed five gates of the Garang regulator and washed away the entire structure."

The importance of Sukkur Barrage and the canal network that extends from it is described in this old Pakistan Observer article "Federal Minister for Labour and Manpowewr Syed Khursheed Ahmed Shah has said that Sukkur Barrage is the lifeline for Sindh’s agricultural economy". Agriculture in this area is heavily dependent upon the water delivered by this canal network; damage to these structures will represent a major problem in the future. Note also that it is likely that the water will have carried subtantial volumes of silt, which may be deposited in the canal network. This may need to be removed once the floods subside. Meanwhile, the water will have destroyed a substantial part of the cotton crop, which should be harvested next month, which in turn will damage the textile industry. Farmers would normally plant winter wheat in the autumn; the viability of this crop must also be in doubt.

Upstream, the impact of the floods and landslides in the mountains is being well-described by the Pamir Times. The Pakistan High Commissioner in London has stated that rehabilitation will require about $15 billion of investment and a "Marshall Plan" style of approach. It is interesting to see the UK Deputy Prime Minister describing the international response to the floods as "lamentable". To date the UK has committed £31 million to the Pakistan flood disaster, which to be fair is reportedly a quarter of all of the assistance pledged. However, in comparison with the cost of the Afghanistan and Iraq wars (£20 billion over the last ten years for the UK alone), this amount is tiny. Investing in aid to Pakistan, and being seen to be a force for good in a troubled area, would seem to be a good strategy. Building on the Marshall Plan analogy, isn't it time for a Berlin Airlift style aid effort?

Where on Google Earth 211 (updated with result)

2010-08-16T20:29:00.001+01:00

There is a long running competition in the Geoblogosphere called "Where on Google Earth" (WOGE), which essentially challenges readers to identify locations pictured on Google Earth imagery. The last was WOGE (number 210), hosted by Meta-Geologist; I was the lucky winner. The winner gains the right to choose and host the next one, so here it is:

The rules of Where on Google Earth are that to win you must post in a comment the location of the image (lat, long), together with a brief description of the reason for its geological interest. The prize is the right to produce and host the next one. You will be unsurprised to hear that the site in question contains a landslide - in this case very a large one.

RESULT: Both Christoph and Jorge were correct in the location. There is indeed an ancient, cubic kilometre scale rock avalancke deposit in the valley, and upstream there are extensive lake deposits. On the basis of this, I declare Jorge the winner, who now gets the right to set the next one.

Dave

The rapidly developing flood crisis in Pakistan: 16th August 2010

2010-08-16T09:46:00.000+01:00

The flood crisis in Pakistan continues to develop with a surprising pace. In an earlier post I suggested that this event might be Pakistan's equivalent of Hurricane Katrina (i.e. a wake-up call for effective disaster management), but now it is starting to look more like the equivalent of the Haiti Earthquake - i.e. an event that is so catastrophic that the coping capacity of the state is exceeded. There is clearly now a need for a huge international response effort.

The PakMet FFD hydrograph data continue to plot the progress or otherwise of the flood waves downstream. Most of the the first flood wave continues to be trapped between Guddu and Kotri. The Kotri hydrograph continues to show alarmingly low discharge values (click read more below to see the remainder of this post):

Thus, the majority of the water from the first wave is still in the landscape as the second wave approaches. At Guddu the discharge is rising again:

Note that it is still substantially above the "exceptionally high" level. The real concern however must lie in the area around Sukkur, where the water level has hardly fallen from the first event, and is now just starting to rise with the second:

Unfortunately, further heavy rainfall is occurring both in the upstream areas and those downstream as well. The FFD warnings are now expressing quiet concerns about the barrage at Sukkur. The politicians are a little more frank about the situation, according to this report in Dawn:

"The Sindh irrigation minister, Jam Saifullah Dharejo, said the dam in Sukkur faced a major test of its strength as flood waters coursed down the Indus River into Pakistan's highly populated agricultural heartland. ''The coming four to five days are still crucial,'' he said.

Take a look at the Pakistan media reports here, here and here to get an idea of just how bad things are in Sindh now. The prospect of 200,000 people being rendered homeless by a single part of this flood in a single day is quite extraordinary.

Meanwhile, life in the mountain areas to the north is extraordinarily difficult, with areas devastated by the 2005 earthquake being hit by fresh landslides overnight. The Express Tribune has a short article on life in Gilgit, which remains effectively isolated from the outside world. The headline is: "Gilgit travels back in time as flood cripples infrastructure", which given that electricity, food, water and medical facilities are all in a state of crisis, is no exaggeration.

Pakistan flood update - 15th August 2010

2010-08-15T08:24:00.001+01:00

The second flood wave is now starting to affect the most devastated areas of Sindh. The PakMet FFD hydrograph for Guddu has started to show an increase in discharge once again:

Note that the flood level has been above the exceptionally high (danger) level for ten days now. Downstream at Sukkur the water level continues to fall very slowly, again remaining well above the danger level:

Expect this to start to rise once again in the next few days. Meanwhile, the final downstream station at Kotri the flood level remains very surprisingly low:

Assuming that these values are correct this must mean that a vast volume of water is being stored in the landscape between Sukkur and Kotri. The flood is certainly spreading across the plains, as this report on new flooding in Jaffarabad demonstrates. This NASA MODIS satellite image shows the area around Sukkur. Notice how the area flooded changes at Sukkur, presumably because of the restriction in the flow by bridges and barrages:

There is a first class UNOSAT flood extent map here. It demonstrates the areas in which the flood is still spreading - a close look is quite horrifying actually - the scale of the disaster is so huge that the media are understandably struggling to provide an adequate picture of the extent.

To multiply the problems the new flood wave travelling down the river. This must be a very worrying situation once the second flood reaches Sukkur. Although smaller than the first wave, the cumulative effects and the existing damage to levees spells a potentially very difficult situation.

Meanwhile, the focus of the media coverage is now on the downstream areas. With 20 million people now directly affected by the floods, this is unsurprising. However, the situation upstream also remains critical. The Pamir Times has a good report on the situation in Gilgit-Baltistan, which is effectively cut off downstream by the loss of the Karokoram Highway and upstream by the Attabad landslide dam:

"The devastating landslides and flash floods that resulted in death of over 120 people in different parts of Gilgit – Baltistan have also blocked supply routes increasing misery and sufferings of hundreds of thousands more.

Blockage of the Karakuram Highway since last week of July has resulted in depletion of POL products, including petrol, diesel and Kerosene oil in the entire regions. Hospitals have been closed and hotels are shutting down due to absence of electricity. Banks have also closed down temporarily because of lack of electricity.Supply of electricity to Gilgit has been cut off for more than one week due to destruction of power houses and transmission lines. Transportation system has also collapsed due to closure of fuel stations that relied entirely on supplies from down country through the Karakuram Highway. In Gojal valley the boats have stopped ferrying passengers and goods because of depletion of fuel reserves. The local people are cut off from other parts of the region without proper medical facilities and supplies. Ghizar, Astore, Diamir and the two districts of Baltistan are also facing similar situations. Hundreds of displaced families in different parts of the region have still not been reached by the government and relief agencies. One such example is of the displaced people of Gaise village in Diamir where the food reserves have reportedly finished and starvation is setting in. Local people have demanded of the government to intensify its efforts in Gilgit – Baltistan to end miseries of the suffering people. Deaths due to starvation and malnutrition seem to be a sad possibility in some far flung parts of remote affected districts of Gilgit – Baltistan."

Jeff Master's remarkable blog has an article on the causes of the Pakistan floods. It remains my plan to follow this up in the next few days, if I can find the time given everything that is going on.

An extraordinary year for landslides in China

2010-08-14T11:36:00.001+01:00

This morning has brought further reports of heavy rain and consequent landslides in China, with more downpours forecast for the next few days. Meanwhile the recovery operations for the Shouqu landslide continue, marked by a national day of mourning for the victims. Note that the cost of the landslide at Shouqu is now reported to be 1239 people, with 505 still missing.

The landslides in China this year are interesting for both their frequency and their intensity. On average China has the largest number of fatal landslides of any country in the world, but this year has been particularly serious. Based upon the database of fatal landslides that I have been maintaining for the last 8 years, the graph below shows the cumulative recorded number of non-seismic landslides that resulted in fatalities for the last five years in China. The x-axis is the day number in the year (i.e. 1st January = 1; 31st December = 365).

Even before the Shouqu landslide disaster the number of fatality inducing landslides this year was running far above the normal level for the previous four years, and already the total has exceeded the annual totals of all the previous years. This is despite a low impact of landfalling typhoons so far this year (this is unlikely to remain the case to year end).

The Beijing Climate Center produces daily maps of global precipitation anomaly for the last thirty days. This is the latest version covering the last 30 days:

The most obvious aspects of these maps is actually the extraordinary drought in western Russia, but note also
that the high level of rainfall in northern Pakistan and in Central Europe appears. Much of China shows rainfall well above the norm.

Update on China and Pakistan - 13th August 2010

2010-08-13T08:31:00.000+01:00

1. The Gansu landslide in China
The rescue operations in Gansu have now clearly transitioned into a recovery and rehabilitation phase, greatly hampered by continuing very heavy rainfall in the area. Landslides are continuing to occur in the area, with resultant casualties.

Tom Dijkstra of Loughborough University visited the site as part of a trip to look at collaborative landslide research in the area back in November. He has kindly sent two images of the town to me and has agreed that I can put them online. This image shows the area affected by the landslide from the other side of the river. The steep, deforested mountains in the background are clearly the source of the flow:

The second image shows the catchment source of the flow:

It is worth comparing the above image with this AP picture that I posted a few days ago of the site after the flow:

The reasons for the very high loss of life, now estimated to be 1,144 people, with a further 600 still missing, are clear given the density of buildings in the affected area.

2. Pakistan
The two flood waves in Pakistan continue to cause extreme levels of suffering. According to the FFD hydrographs the water level at Sukkur is now falling slowly after the passage of the first flood wave:

What has been particularly interesting though is that the flood level is not really increasing substantially at Kotri, the large gauging station downstream:

This presumably means one of two things. First, it could be that the water is finding another route - i.e. that it is bypassing the gauging station. Alternatively, the water is in effect trapped between the two sites, which might explain the very slow falling limb of the hydrograph. The Google Earth satellite image below shows Kotri:

It is possible that the water has flooded the adjacent land, but the news reports indicate that this is not the case, with the suggestion that the bridges downstream of Sukkur are slowing the flow down. This is dangerous in the context of the second flood wave, which at the moment remains smaller than the first. This is the hydrograph for Taunsa, which is just below the "Extremely High" flood level:

At Guddu the discharge is still falling, but only very slowly. Indeed the discharge remains well above the "Exceptionally High" level:

The danger must be that the second flood wave starts to catch up with, and build upon, the stalled first wave. This would create the potential for an extremely damaging second phase of floods. It took six days for the first wave to pass from Taunsa to Guddu, and a further day to Sukkur. The hope must be that the water level starts to fall quickly at these two sites before the second wave arrives.

Unfortunately, it is clear that this slow motion disaster has several more weeks to go, even if there is no further heavy rain.

Update on the disasters in China and Pakistan: 11th August 2010

2010-08-11T20:44:00.000+01:00

Apologies for the tardiness of this update - it has been a busy day! First a heads-up, I will write a post to go on the Institute of Hazard, Risk and Resilience blog on these disasters in the context of climate change in the next couple of days. I will signpost the piece here when it is ready.

1. Pakistan
The sheer magnitude of the disaster in Pakistan is difficult to comprehend. Unfortunately the true horror of this event is probably remaining hidden; the real impact will come when the water levels in the south subside to leave polluted water wells, destroyed homes and wrecked crops. The legacy of this disaster will be long-lasting, and will have a profound impact on Pakistan and elsewhere.

Starting in the north, heavy rain continues to wreak havoc, and the Pamir Times appears to be the only outlet from which a really good idea of the true impact can be gained. In Gilgit-Baltistan the population is isolated by the blockage of the Hunza river to the north, preventing supplies from China, and the loss of bridges and the road to the south, leaving the population in dire need. Electricity, water, food and medicine are in short supply. Meanwhile, the Pamir Times is also reporting a disaster at Diamir, caused by the failure of another landslide dam. They report at least 50 fatalities and 300 houses washed away. Assuming that the report is correct, expect this to make the news tomorrow as word seeps out. One hopes that the toll does not increase further, but I am fearful that this is likely.

To the south, the media has cottoned onto the fact that there is a second wave heading down the Indus now, an issue that I have been highlighting since the weekend. Dawn.com quotes the meteorological service in warning of floods in the northern regions of the Pakistan plains. This second wave is now generating a substantial flood at Chashma:

Fortunately it is not as large as the first wave, but is still only just below the "extremely high" category. In the context of already damaged infrastructure, the potential for further destruction is clear.

Downstream at Guddu the hydrograph is falling very slowly, but remains far above the extremely high flood level:

Whilst at Sukkur the hydrograph remains saturated, meaning that the true level is hard to judge:

Unfortunately the first flood still has some way to go before discharging to the sea. The Pakistan Flood Forecasting division must be praised for the brevity of their weather forecasts. Tomorrow's forecast says:

WEATHER OUTLOOK FOR NEXT 48-HOURS: No Change.

Several people have asked about a good NGO to whom donations could be made. In this blog I have worked extensively with Focus Humanitarian Assistance, who specialise in providing help to people's affected by disasters, and who did undeniably wonderful work in Pakistan in the aftermath of the Attabad crisis. As part of the Aga Khan Development Network I believe that they are a safe and honorable NGO, and they remain my preferred partner for work in Pakistan.

2. China
Once again the death toll from the Zhouqu landslide in Gansu has jumped, with Xinhua reporting a total of 1,117 fatalities and a further 627 people still missing. The struggle to breach the partial barrier formed by the landslide across the barrier is intense, with the use of explosives to try to break the blockage. Concern is rising in the light of continued poor weather in the area, with thunderstorms occurring today and heavy rains forecast for the next two days. Meanwhile, there is a fascinating level of honesty in the Chinese media about the likely causes of the landslide. For example, this article explores the contributing factors, whilst in this one a minister reflects upon both climatic extremes and illegal construction. The level of openness is surprising, but very welcome.

The press of course continue to describe the anguish of the families of the victims, especially as the "golden" 72 hour period is now passed. Presumably a decision will be needed soon to terminate the rescue operation and to regrade and entomb the debris. I suspect that it is inevitable that many of the victims will not be recovered, with the site being preserved as a memorial to them.

Finally, Digital Globe have released a very high resolution satellite image of the site of the landslides, which is available here:

Very useful, but unfortunately, it still does not provide an insight into the source area of the slide - has anyone seen an image of this zone as yet?

More tomorrow.

Update: Dramatic increase in the loss of life in the Gansu landslide

2010-08-10T12:12:00.000+01:00

Xinhua has this morning dramatically increased estimated loss of life in the landslide at Zhouqu in Gansu Province, China. The latest toll is 702 known fatalities and a further 1,042 people missing.

Updates for Pakistan, China and India flood and landslide crises, 10th August

2010-08-10T08:47:00.000+01:00

As yesterday, this is a brief review of the state of play with the three substantial landslide and flood crises in Asia.

1. Pakistan
The flood wave continues to work its way down the Indus, and is now in the Province of Sindh. As forecast, heavy rainfall exacerbated the situation yesterday, with totals of over 100 mm in some areas of the province. Kyber-Pakhtunkhwa also saw falls of 30 mm or more in some areas. Whilst not enough to cause the sort of devastation that we have seen of late, this is sufficient to keep river levels topped up.

Working our way down the Indus, the second flood at Besham has now peaked and the hydrograph is showing a rapid decline.

The peak flow in this econd flood was lower than in the first , but was still substantial. This water will of course have to work its way down the Indus over the next ten days. It will be interesting to see how this flood looks when it reaches Taunsa.

Moving down to Guddu, the peak discharge appears finally to have passed, meaning that water levels will be slowly falling. Note however that if the flow behaviour at Taunsa is a guide, the rate at which the water levels fall will be quite slow, meaning that the people have several more days before they will be able to start rebuilding their lives. Note also that the flood level is still above the exceptionally high level. The flat peak component of the flood record causes me to reiterate my suggestion yesterday that the hydrograph shown below has not accurately captured the peak flow:

Going south again, and the main concern is now at Sukkur, where the hydrograph appears to be suffering the same problems of saturation at the peak:

Some media reports have suggested that the peak flow here is actually 1.2 million cubic feet per second. The media are also reporting concerns about the safety of the Sukkur barrage, with several reports suggesting that deliberate breaches of levees are being considered to try to reduce the peak flow. It seems that a similar exercise was undertaken upstream at Ghouspur, with the inevitable destruction that followed. However, it is important to understand that these barrages provide irrigation for vast areas of productive agricultural land that is vital for the sustenance of the population of Pakistan. Deciding on how to protect them is not an easy task.

However, as at Attabad the apparently poor communications strategy of the authorities is unfortunate. Whilst putting the hydrographs online is a good step, it would be sensible to accompany this with a decent explanation of what is happening, where the threats lie, and the action that might be needed to mitigate them. Whilst this would not prevent the destruction, at least people might understand why particular courses of action are being followed.

Finally, for northern Pakistan the Pamir Times has provided two updates in the last 24 hours on the Attabad situation. Most importantly, the water level is now falling, having apparently risen by 6 feet (about 1.8 metres) at the peak of the floods, which caused further widespread destruction. Meanwhile, they continue to note that other landslides have caused severe hardship, and that the Hunza was blocked at Rahimabad to the north of Gilgit. As far as I can tell Rahimabad is in the valley shown in the Google Earth image below:

Meanwhile, the Pamir Times has also provided some new images of the state of the Attabad barrier itself:

These appear to indicate little change in the state of the dam over the last couple of weeks. Operations to lower the spillway level have yet to start, but it is heartening to see in some of the images that a monitoring team appears to still be on the site.

2. China
Rescue operations continue at the Zhouqu landslide site, where the number of known fatalities is now 337. The reported number of missing people is 1,148. There can be little chance of recovering many further survivors, although one victim was recovered alive today. The state media are reporting some tales of real anguish in the aftermath of the disaster, exacerbated of course by the "one child" policy in China. The government is attributing the disaster to the normal villains - poor geological conditions, the recent drought, the heavy rainfall, and the aftermath of the 2008 earthquake. This is all likely to be true to at least some degree, but there may be other factors as well, most notably deforestation and the legacy of mining activities. The internet age has spawned a wave of amateur investigative journalism in China. This All Voices page reviews recent postings of Chinese documents about the landslide hazard in Zhouqu. Whilst I am naturally sceptical of some of this material, it does appear that the risks to communities posed by landslides in these mountains is well-documented. In particular, this newspaper article, from 2008, identifies that the slope problems at Zhouqu are sufficiently serious that they have been the location of various studies by Japanese landslide scientists. However, to be fair to the government, the range of landslide problems in the aftermath of the 2008 earthquake is so serious that prioritising and finding resource to mitigate appropriately is impossible. Expect more landslide disasters in central China in the coming years.

Two images have appeared in the last 24 hours that demonstrate the magnitude of this slide. This AP image shows the landslide from the opposite bank:

I would really like to see the source of this huge debris flow - has anyone seen an aerial image of the upper reaches of the track as yet?

And this AP image illustrates the likely velocity of the movement, given away by the mud deposit on, and indeed in, the upper part of the building:

Finally, unfortunately tropical storm Dianmu is moving northwards off the east coast of China. Although it is unlikely to landfall in China itself, expect heavy rainfall across eastern and central China. Given the intensity and magnitude of the recent rainfall, this is potentially deeply problematic.

3. The Ladakh debris flows in India
The forgotten disaster amongst everything else that is going on is the Ladakh debris flows that occurred on Friday. To date the number of known victims is reported to be 165 people, with a further 500 thought to be missing (with very little chance of survival now). However, Save the Children is reported to believe that the true toll is likely to be in excess of 1,000 because several affected villages have yet to be accessed. Localised heavy rainfall continues in the area, disrupting relief operations and causing further damage.

One of the most seriously affected towns was Choglamsar. This is the settlement in the foreground of the perspective Google Earth image below - the presence of the huge debris fan in the background is a clear sign of the processes that have allows the formation of the comparatively flat areas upon which the town is built:

Protecting the town against repeats of this event is not going to be an easy task, but debris flows must be expected on a fan such as this.

I will try to provide further updates tomorrow morning, or sooner if events require.

Updates on landslides and floods in Pakistan, China and India

2010-08-09T11:59:00.000+01:00

It is rather difficult to keep up with all the landslides occurring in Asia at present, so for now I'll provide a brief review of the current situation across the three major areas affected:

1. Pakistan
The situation in Pakistan becomes increasingly desperate. Further heavy rainfall in the mountains in the northwest has meant increased landslide and flood occurrence, and a huge reduction in the aid effort. The FFD hydrographs in the mountain areas are steadily rising again. For example, this hydrograph is for Skardu shows that flow is greater now than it was in the heavy rainfall of ten days ago:

Downstream at Besham (close to the mountain front) the discharge is not as high as it was in the first set of floods, but it is rising and the level is undoubtedly high:

The area under the curve is the total volume of water that has been involved in the flood. This suggests that in terms of overall volume this flood is larger than that of the events last week, even though the peak flow is (so far) lower.

Downstream at Sukkur and Guddu the flow remains exceptionally high. At Guddu the hydrograph suggests that the peak flow has now been maintained for over 24 hours. This looks odd - I wonder whether the discharge has exceeded the capacity of the measurement system.

However, according to the FFD a larger discharge has been measured at Guddu before - in 1986 a discharge of 1,200,000 cusecs (cubic feet per second) was measured at this point.

At Sukkur the discharge is continuing to rise, and based upon the Guddu hydrograph may have some time to go before the peak is reached. The maximum recorded flood at this point is 1,170,000 cusecs in 1986.

GEO News is reporting that the city of Muzaffargarh is now being evacuated. Given that this is a city of 165,000 people, the severity of the situation is clear.

2. China
Xinhua continues to provide full coverage of the desperate attempts to save people trapped by the landslide in Zhouqu, Gansu Province yesterday. The magnitude of the slide is clear from the story of the survivor rescued this morning - she was recovered from a an apartment that had been inundated by debris. The rescuers had to break through a wall to reach her - even though her apartment was on the fourth floor of the building. Meanwhile the landslide dam has been successfully breached, which at least deals with one key issue.

3. India
The debris flow at Ladakh is now known to have killed 132 people, but a further 500 people are reported to be missing. The level of damage is really very high indeed, as this AP image shows:

A fascinating insight into the process that occurred at Leh is provided by this commentary from geologist Ritesh Arya, who was in the head scar area when the failures developed:

"Speaking to TOI on phone from Leh, Arya, who was sleeping in a house in Choglamsar village when the entire area abruptly began to move, said: "This village is 6km from Leh on a hillock formed by mud itself. I woke up when I felt massive vibrations and found that the whole hill-side was moving." The loose soil had softened further due to torrential rains. "This is a rare geological phenomenon, and though landslides are common, mud creeps like this are unheard of," said Arya, who holds a Guinness Book of World Record for discovering ground water at an altitude of 11,000 ft in Ladakh.

Describing the sheer size of the mudslide, Arya said: "Its dimensions make it so scary: it was about 20meter high and several kilometers wide." All the houses coming in its way appeared to just dissolve into it as it roared on, destroying the Leh bus stand and the BSNL exchange, said Arya. The mudslide is believed to have travelled 6km, bulldozing the Choglamsar village. Arya said most roads have disappeared under the debris. The worst-hit are the heritage buildings and old houses, traditionally made of mud.

"'People were completely caught unawares. Then suddenly, everyone started scrambling as the enormous amount of loose mud and debris was unleashed. Those who survived in the Choglamsar village had to waded through five-ft high mudflow," said Arya. "There are bodies still buried in the debris and I found arms and legs sticking out at several places," he said."

Whilst elements of this are over-hyped (for example this is far from "unprecedented"), the observations are very helpful and interesting.

First video of the Gansu landslides

2010-08-08T21:10:00.002+01:00

The Chinese State TV company has a new report (in Mandarin) that provides aerial footage of the Gansu landslide site. It is clear from the video that there are in fact two slides. The video is available via the link below (I have removed the embedded video as it played automatically):

Video available here.

The larger of the two slides is shown in this screen capture from the video:

Strangely though neither of these two slides appear to be blocking the valley, as this screen captured image shows:

Does this mean that there is another landslide downstream that is blocking the valley?

Update: the Gansu landslide

2010-08-08T15:47:00.000+01:00

Xinhua now reports that the death toll from the Gansu landslide is 127 people, with a further 1,294 people reported to be missing. So far just 28 people have been rescued alive.

The BBC has published an image of the lower part of the slide:

Note the water flooding the lower storey of the buildings in the background.

Meanwhile in Northern Pakistan...

2010-08-08T11:49:00.000+01:00

Amidst the appalling tragedies playing out in southern Pakistan and in China, Northwest Pakistan continues to grapple with its own problems. Unfortunately the problems at Attabad have not gone away as yet, even though the NDMA reports on the situation have now dried up completely. However, the Pamir Times are still on the case, with a somewhat concerning report yesterday that "Three more houses were dismantled in Gulmit Gojal due to sudden increase in water level of the dammed Hunza River...Rains and floods in different parts of Gojal valley have taken the water level up by around three feet during the last 36 hours, according to local people."

That new houses are being dismantled suggests that the lake is at its highest level so far. I do hope that the spillway is being watched carefully.

Meanwhile, the Frontier Post reports two substantial landslides in Gilgit-Baltistan on Friday and Saturday. The first occurred at Qamrah village in Skardu district late on Friday night, reportedly killing 35 people. The second occurred in Shout village in Ghanche district, killing four people. Flash floods are also causing substantial problems.

Images of the Meager Creek landslide in Canada

2010-08-08T11:23:00.000+01:00

The Meager Creek landslide in British Columbia, Canada on Friday was a very large and very energetic event. The latest estimates suggest that it had a volume of about 40 million cubic metres, making it one of the largest slides in Canada in recent decades. Indeed, the Vancouver Sun quotes Rick Guthrie in stating that the slide travelled at 30 metres per second over a distance of 10 km.

Some good images of this event are now available, despite the smoke-filled air (the smoke is from local forest fires). Worth a look is the Global Winnipeg gallery of the slide here, from which these images are derived:

This image shows the location at which the slide entered the main valley and then spread. Note the way that the trees on the far valley wall have been stripped off by the flow. This is called super-elevation and is an indication of the speed of the flow. To generate this degree of super-elevation the flow must have been moving very quickly.

This is a view from the opposite side of the valley looking up the main flow. Note the small lake forming upstream of the blockage. This problem has now apparently been resolved.

This image shows the flow path of the slide down the valley. Again, note the stripping of vegetation up the valley walls, suggesting a very considerable flow depth.

This is the upper reaches of the main slide, giving a great perspective on the magnitude of the flow.

The very best images of the slide are available on the Flickr page of DBSteers, a member of the Search and Rescue team that flew over the slide. The images are explicitly copyrighted, so I will not reproduce them here, but I strongly recommend that you take a look. The page is here:

http://www.flickr.com/photos/dbsteers/

Take a look - you won't regret it!

First image from the Gansu landslide

2010-08-08T10:38:00.000+01:00

Xinhua has now published an image, apparently taken using a mobile phone, of the landslide in Chengguan town:

It is now clear that the landslide affected Zhouqu town, which is shown on the Google Earth image below:

Unfortunately, high resolution images are not available on Google Earth for this area. These two Panoramio photos give a good idea of what the town and adjacent mountains are like:

Source

Update on the Pakistan floods: 8th August 2010

2010-08-08T10:18:00.000+01:00

The Indus flood wave is continuing to flow steadily southwards across the country. The annotated WHO flood map below, from my earlier post, is for reference in terms of the locations of the hydrograph stations:

The Pakmet hydrograph data shows that the water level at Taunsa is now declining markedly, although it remains in the defined "high" flood category:

Downstream at Guddu, the discharge has been rising, although it should now be close to the peak level:

Downstream at Sukkur, which is the area that is attracting most of the media interest at present, the discharge has been increasing very rapidly:

The barrage here apparently has a design capacity of 900,000 cubic feet per second, which is clearly a concern, although it is likely that it will survive the flood. Other agencies have suggested that the design flood is as high as 1.5 million cubic feet per second. It is however reported that a 25 m wide breach occurred in a levee at Kandhkot, about 70 km upstream of Sukkur. Other levees are showing signs of distress, and one levee (at Ghouspur) has been intentionally breached to try to reduce the size of the flood wave.

The final station downstream is at Kotri. Here water levels have yet to start to rise rapidly. The peak of the flood wave is expected to arrive in two or three days from now:

Meanwhile, the official weather forecast states "widespread rain-thundershower, heavy at times, expected in Punjab, Sindh, Eastern Balochistan, Khyber-Pakhtunkhwa and Kashmir."

The impact of these floods on the long term welfare of the people of Pakistan should not be under-estimated. The combination of loss of life, loss of personal assets, loss of dwellings, loss of crop, damage to infrastructure, loss of sanitation and loss of clean drinking water across such a large area cannot be underestimated. That aid agencies are describing this as being worse than the 2005 earthquake, which is thought to have killed 100,000 people, gives an idea of the scale of the catastrophe. I would also note that, given the troubled history of this area, there is a very real opportunity for Europe and the US to be seen to be a force for good by providing a proper and effective response to the disaster. This would surely be a good investment for the future of both Pakistan and the west.

Updated: A devastating landslide in China is reported to have killed at least 96 people

2010-08-08T09:16:00.003+01:00

Updated at 09:40 UT to provide the correct location.

The dreadful effects of the 2010 summer monsoon continue. Over the next couple of hours I will try to provide an update on all of the events of the last 36 hours, but I'll start with the overnight landslide in China.

Xinhua reports that "At least 96 people have been confirmed dead in landslides triggered by torrential rains in northwest China's Zhouqu County, Gannan Tibetan Autonomous Prefecture in Gansu Province, said local resuce headquarters. As of noon, more than 680 residents had been rescued.".

Judging by the CCTV report available here, the landslide appears to have occurred downstream of Zhouqu town, creating a barrier lake that has now flooded the city centre. The landslide is reported to have occurred at 1 am local time. There may also have been some debris flows - this rather poor image, captured from the CCTV footage appears to show a debris flow deposit:

Some Xinhua reports suggest that up to 2000 people may be missing, but this information should be treated with great caution at this stage as it is likely that the true picture is confused at the moment. However, as the Chinese Premier is on his way to the site it is likely that this is very serious.

A Google Earth perspective view shows the mountains around Zhouqu town:

It is not yet clear where the landslide occurred, or which part of the town has been affected.

I'll post again on this as more information becomes available. First update available here.

Landslide at Meager Creek, British Columbia, Canada

2010-08-06T20:39:00.001+01:00

Thanks to Robin Beech for the heads-up on this one. CBC News is reporting a large landslide at Meager Creek, a hot springs area north of Pemberton:

"A two-kilometre-wide landslide has been reported near Meager Creek Hot Spring, about 95 kilometres north of Pemberton, B.C. The flow of rock and soil debris has covered a river in the area, causing water to become dammed upstream of the slide. Authorities say an unknown number of people are trapped in the area, but there is no word on injuries."

This appears to be the Meager Creek area:

Image from here. CTV has a very poor quality image of what appears to be a large slide:

Even the most cursory look at the Google Earth image for this area shows that this is certainly not the first large, valley-blocking landslide in Meager Creek:

Debris flow disaster in Leh, Indian Kashmir

2010-08-06T08:17:00.001+01:00

Thanks to several people for the heads up on this. Various Indian news agencies are reporting that the town of Leh in Ladakh, Indian controlled Kashmir was hit by a series of debris flows / flas floods triggered by a cloudburst. The reported death toll is currently reported to be at least 50, and may increase substantially.

This Panoramio image gives a fairly good idea of what Leh is like:

A new valley-blocking landslide in Nepal

2010-08-06T08:05:00.000+01:00

Thanks to Ripendra Awal for the heads-up on this one. The tale of monsoon devastation in South Asia continues with new reports of a valley blocking landslide at Setikhola village, which is located in Narmajung VDC in Kaski District, Nepal. The landslide occurred on the morning of 3rd August, killing five people according to press reports. So far 300 people have needed to be moved due to flooding on the upstream side of the blockage.

This perspective Google Earth image shows the landslide location - the image is from April 2008:

Unfortunately, the size of the blockage is unclear at present. This map, prepared by Ripendra, shows the river network:

Update on the Pakistan floods: 6th August 2010

2010-08-06T07:39:00.000+01:00

The flood wave in Pakistan continues to travel down the Indus River and is now approaching Sukkur. The authorities are responding with a large-scale evacuation of low-lying communities - The Nation reports that 500,000 people are being relocated but that 1.5 million people are likely to be affected.

The latest FFD hydrographs depict the situation very clearly. The locations of the gauging stations are shown on this annotated 2007 OCHA map of national flood potential for Pakistan:

At Taunsa the FFD hydrograph is now on the falling limb, but the discharge is declining slowly:

Meanwhile, as expected the water level at Guddu is continuing to rise towards the million cubic feet per second level, and is now substantially above the extremely high flood level:

The low-lying telief around Guddu is clear in this Google Earth image of the area:

The barrage evident in the image above is deigned to direct flow into the channels on either side of the river, which then provide irrigation to about 12,000 square kilometers of land. Clearly, damage to this structure would have a substantial impact, but the reported capacity is 1.25 million cubic feet per second.

The next key location downstream is Sukkur, where the hydrograph is now showing rapid increases in discharge:

The Google Earth image of Sukkur shows that it is a much larger settlement:

Sukkur also has a barrage, as shown on this Panoramio image:

This barrage provides irrigation to 20,000 square kilometres of land. Damage to the structure would be serious. The reported capacity is 900,000 cubic feet per second, so it should survive.

Finally, downstream is Kotri, where the discharge is also now starting to increase:

It will be a few more days before the main flood reaches this point.

Meanwhile, the Pamir Times has published another set of images of the state of the Karakoram Highway, of which this is the best:

Two things to note here. The obvious one is the huge amount of material deposited on the road by this debris flow. The other is the huge queue of trucks in the background. These trucks are trying to travel southwards out of the mountains.

A further update on the Pakistan floods

2010-08-05T19:46:00.001+01:00

The media have now cottoned onto the fact that the flood wave is causing destruction downstream from the northwest of Pakistan, an issue that I have been highlighting for some days. The flood waters are certainly abating now in Taunsa, although note that three days after the peak the discharge is still above the "very high" level:

Meanwhile, at Guddu the water level is still rising, and is now close to the "extremely high" discharge level. It is expected to peak in the next 24 hours.

The discharge at Sukkur is now very much on the rise as well as the flood wave starts to approach:

It is frightening to think that this flood has at least five days to run before it discharges into the ocean. There is a huge amount of damage yet to occur.

Meanwhile the Pamir Times has published a further set of images of the Karakoram Highway, amongst suggestions that it will take six weeks to reopen it. The latest images are well worth a look - the damage is very serious indeed:

As I noted during my drive up this road in February, a huge amount of investment has been made in the last couple of years in this road, with lots of work on new, inadequate, culverts. It is tragic that so much of this investment will have been wasted. Meanwhile, the hardship suffered by those upstream of the Attabad barrier will have been amplified by the lack of communication along the remainder of the road. One genuinely has to fear for the welfare of those living in Hunza now.

Unfortunately, there is now no data about the state of play at Attabad itself. The continued threat posed by the dam could be forgotten amongst the flood tragedy. This must not be allowed to happen.

Latest update on the flood wave in Pakistan

2010-08-04T08:10:00.000+01:00

The flood and landslide disaster in Pakistan continues to play out in slow motion. The recovery operation in the north of the country continues to be hampered by the level of destruction inflicted upon the roads. The Pamir Times yesterday posted some images of the Karakoram Highway north of Gilgit, which serve to show all too well just how difficult the recovery operations are going to be:

The areas affected by the flood, and those that will be affected over the next few days, are shown on this new map from OCHA:

A good sense of how bad things are in the northwest of the country can be gained from this Save the Children rapid assessment report for the Swat Valley. They found that, for example:

21% of housing structures have been damaged;
3% of housing structures have been effectively destroyed;
Only 28% of household have access to a functional latrine;
In the 80 surveyed communities, there were 75 reported cases of separated children, 6 cases of missing children, and 16 children who have lost one or both of their parents.
26% of school buildings have been damaged
54% of communities reported that most families in their communities have no food stock available at home
Only 1.5% of communities reported to have received food aid
For 45% of surveyed communities, the main sources of drinking water are rivers, ponds, or lakes
55% of communities reported that injured and sick community members are not receiving any medical treatment.

Meanwhile the flood wave continues to move downstream, causing misery as it proceeds. Judging by the PakMet hydrographs. It is now clear that the flood has peaked at Taunsa (for locations see my earlier post; they are also marked on the OCHA map above):

Whilst the river level is now rising rapidly at Guddu:

And has started to rise at Sukkur:

Meanwhile further rain is forecast for Sindh today, which could serve to exacerbate the situation.