Another landslide video - car hit by landslide in Japan

There has been an extraordinary flurry of landslide videos of late (e.g. here) presumably reflecting both the high occurrence of landslide events and the ubiquity video sharing sites. Another has appeared this morning - this time from Japan. The video should be embedded below or can be viewed here.

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I guess this is not as spectacular as for example this one, this one and this one, but is interesting nonetheless. The occupants of the car were lucky that the slide did not engulf the car or push it off the road. One interesting aspect is the way that the car was bulldozed rather than being buried, which is a useful observation when we think about the rescue of survivors.

Does anyone know where in Japan this happened? The date on the video appears to be 31st January.

World Landslide Forum Report

Readers will probably be aware that last week the First World Landslide Forum was held at the United Nations University in Tokyo. This was apparently "a global cooperation platform for all types of organizations from academia, United Nations, governments, private sectors, and individuals which are willing to contribute for landslide and other related earth system risk reduction."
Unfortunately I wasn't able to attend, but two of my colleagues (Nick Rosser and Mike Lim) were there and have kindly written the following conference report. Thanks very much to them for doing this.

The First World Landslide Forum was held last week at the United Nations University, Tokyo, Japan. The initiative for this meeting has been driven by the International Programme on Landslides (IPL) under the remit of strengthening research and learning on Earth system risk analysis and sustainable disaster management. The meeting was attended by 450 delegates from 49 countries. Although attracting participants from beyond the normal geo-science conference circuit, there were also notable absences.

Continuing the focus on management issues raised in the preceding Sendai satellite conference, the need to marry scientific knowledge with practical site-specific implementation was stressed in opening addresses by representatives of the many organisations officiating. Konrad Osterwalder gave an eloquent address on behalf of the host United Nations University. He suggested that the crippling costs of landslides, driven by a lack of preparedness, can only be mitigated through a concerted effort towards resilience where the connectivity between the human and natural environments is fully appreciated; a theme which the following sessions attempted to follow. The welcome was concluded with a short play recounting the experiences a group of children who survived the 2006 Leyte landslide disaster. The play was a poignant reminder of the human cost of landslide disasters. Although not as punctual as the Shinkansen, the five parallel sessions of papers covered a range of topics from landslide mapping and early warning to social impacts and interesting country case studies, most with time for discussion.

Amongst the highlights were some interesting contributions from Jon Godt (USGS), Ken Hewitt (Canada), Janus Wasowski (Italy), Masahiro Chigira (Japan), and Sandre Catane (Phillipines). Jon Godt presented recent developments of the USGS near-real-time earthquake induced landslide prediction models, developed upon the PAGER platform. Based on the 1994 Mw=6.7 Northridge earthquake in California, the model uses a combination of modelled peak ground acceleration from tele-seismic monitoring combined with SRTM derived topography, coarse resolution geological mapping and material properties to predict the potential locations of failures. Jon presented an application of the technique to the 2008 Wenchuan earthquake, showing that the results demonstrated a basic similarity with the initial post-earthquake mapping, which was later presented in several papers in this session. Of these the presentation by Masahiro Chigira gave a comprehensive overview with landslide locations mapped primarily from ALOS PRISM data. Professor Chigira demonstrated the concentration of the failures along the fault rupture, with a tendency of failures to follow both topographic ridges, in addition to appearing to follow the main river valleys. A tendency for landslides to be oriented NW – SW was highlighted, most probably reflecting the fault controlled topographic alignment, in addition to some interesting observations of ruptures on calcium carbonate surfaces.

The all encompassing ‘catastrophic slides and avalanches’ session began with an engaging presentation from Professor Ken Hewitt, on his work identifying massive rock avalanches in the Nanga Parbat-Haramosh massif in Northern Pakistan. Ken gave a compelling overview of the changing interpretation of Himalaya landforms, suggesting that the frequency of large rockslides may actually be significantly greater than we believe. Without adequate dating of these now numerous identified failures, their temporal spacing and frequency remains a mystery, but they may hold significant information on mountain chain evolution given their impact and persistence. This is clearly an important subject for further research.

The ‘view from space’ session saw a range of papers, many applying the PSInSAR technique for landslide monitoring. Of note was a critical overview by Janus Wasowski of some of the challenges that remain when applying this technique. Janus demonstrated the apparent mismatch of displacement measurement identified by ascending and descending orbit imagery over a relatively short distance, and noted the problem of scatterer distribution across the area of interest. The other presenters on this subject gave impressive results, though questions remain with regards the ability to compare these results to more conventional techniques and to extract true landslide movement data. A need for presentation of the assumptions and the limitations of the technique alongside the impressive levels of precision is clear. A second predictably impressive paper in this session was given by Fausto Guzzetti, in which he presented the MORFEO project. Here a range of remote sensing imagery is employed to automatically derive landslide susceptibility maps. This work builds upon previous research to use data such as ASTER to characterise the spectral response of landslide scars at the regional scale. Again a promising area for future research.

In the country case studies session, Sandra Catane presented an extremely balanced appraisal of the current progress in landslide risk-reduction in the Philippines. She recounted the increasing awareness of land instability resulting from both climate change and population pressures and highlighted the problems faced by authorities in preventing settlements developing on hazardous areas. A conscious shift has been made by the government away from reactive damage limitation to proactive mitigation measures with the generation of a national coverage of 1:50,000 landslide susceptibility maps. Despite the progress made from the National Geohazards Mapping Program the Leyte and Albay landslide disasters of 2006 demonstrated the need to further improve the hazard management strategies. Sandra concluded by calling for a more formalised links between government agencies, industry and academia in order to develop more effective policies aimed at reducing risk from landslide hazards. The challenge of implementing national strategies successfully at the local scale was a recurrent theme throughout the conference.

The final day of the meeting focussed upon future directions. Overall a useful meeting that brought together a group of scientists and policy makers, with a perhaps notable absence of practitioners. Clearly evident was the disparity between the extreme and the everyday, and the esoteric versus the chronic landslide hazards that ultimately have the greatest cumulative impact. Many researchers are following parallel paths; let’s hope that meetings such as this enable these paths to cross. Clear issues remain including the motivation to study landslide risk (both hazard and vulnerability) in the everyday, and the appropriate transfer of both understanding and technology to those communities most impacted upon by landslides. We hope that the follow-up meeting in Rome 2011 will show progress in these areas.

Conference report: Sendai

Here are my views of the Sendai landslide conference. The meeting was entitled "The First World Landslide Forum Satellite Conference", with the theme of "Management of Landslide Hazard in the Asia-Pacific Region". There were over 200 delegates from more than 30 countries, with many (but not all) Asia Pacific countries represented.

The first memorable contribution was the short but sweet keynote by Alexander Strom. It is being argued by some, including my own research group, that rock avalanches could be used to date very large earthquakes. Prof. Strom showed, using two case studies, that great care is needed in assigning rock avalanches to a seismic trigger when other factors, such as glacial debuttressing, could be the real cause. In one case he was able to show with some certainty that the trigger was a large earthquake, although it should be noted that the evidence remains circumstantial rather than real, whilst the other is likely to have been caused by toe erosion (but note that although this was undoubtedly the cause, the actual trigger could still have been an earthquake). I take his general point, which leaves me to conclude that the holy grail must be a morphological indicator (i.e. some facet of the shape of a rock avalanche scar) that proves (or disproves) a seismic origin. Sadly, such an indicator may not exist.

This was followed by a number of papers that sought to look at rock avalanches as indicators of great earthquakes. Roman Nepop and his colleague Anna Agatova presented a pair of papers that sought to look at the use of rock avalanches in this context, and then also to look at the role of earthquake-induced landslides in sediment delivery. The Wenchuan earthquake has brought this issue into sharp focus. I thought that these were two excellent presentations and I look forward to seeing more from this emerging research group. Masahiro Chigira has been active in visiting sites in which large earthquakes have triggered landslides around the world, including Taiwan and Pakistan. He gave a presentation of the results of a three week field visit to Sichuan in the aftermath of the Wenchuan earthquake this year. He provided a nice spatial analysis of the landslides, showing that the areas of high landslide concentration that they observed were associated with: 1. areas close to the fault rupture and/or 2. areas in which the river valley has become over-steepened. This is very interesting indeed. They also noted a very strong directional anisotropy in the orientation of the landslides, which they ascribed to directionality of shaking. Maybe a little more work is needed on this - for example, to what degree is the orientation of the landslides controlled by the orientation of the valley slopes? However, this is very interesting work. This was supplemented by a very nice presentation by Prof. Zuyu Chen from China, who gave the country report for landsliding for that country. Again, this was a great presentation that inevitably focused on the Wenchuan event. Particularly notable were some videos of the draining of the Tangjiashan barrier lake. During the discussion Prof. Chen was asked what lessons he would pass on to other countries that are prone to earthquakes - he said that one of the keys is to get the seismologists to determine quickly what type of earthquake has occurred as this indicates the type of destruction that can be expected. He also noted that they have collected scientific data on the barrier lakes that is now being written up for publication, so we should all learn a great deal from their experiences.

Suhaimi Jamaludin from CKC/JKR Malaysia presented a very interesting paper on the monitoring system that they have installed on the Pos Selim rock slide in the Cameron Highlands. The quality of the real time monitoring system is very high, but what was particularly interesting was the sequence of images showing the development of the slope (which is this one below).


On a different theme, Senro Kuraoka presented a very elegant analysis using computer modelling of the reasons why large particles migrate to the front of large debris flows. This is significant because this boulder arc causes huge amounts of damage when a flow hits a structure. The analysis suggested that two factors were important. First, the basal friction of the flow and second the ways in which the particles rotate. The author admitted that the results are not definitive, but they are certainly very helpful. The final paper that I saw on the first day was given by Dhakal and his colleagues from Nepal, who gave an overview of the use of bioengineering on road alignments based on their experience in the Himalayan mountain road sector. They presented some very interesting statistics on the occurrence of landslides on valley bottom vs ridge alignments, showing the incidence of failures on ridge alignments is far lower than at the bottom of the slope. I am unsurprised, but hope that this message is finally getting through.

An interesting element of the conference was that two sessions were dedicated to "country reports" in which key landslide people from a number of Asian countries presented their national state of play. I have mentioned already the presentation by Prof. Chen regarding China, but there was also a very nice presentation by Vishnu Dangol on Nepal, focusing very much on national frameworks for management, by Professor Marui on Japan and by colleagues from Thailand, Indonesia and Vietnam. Two key issues emerged for me:

• Many of the speakers in this session mentioned that empowerment at the local level is the way to deal with landslides in less developed countries. This may well be the case, but where is the evidence to support it? I have not seen a single scientifically-driven study that actually establishes the efficacy of this approach, even though it is taken as gospel by almost everyone. There is an urgent need to establish some research to investigate this. Prof. Strom made the point in discussion that maybe it is not helpful to continually remind people of the dangers associated with slopes, given that in most cases the risk is low compared with many other parts of their lives (e.g. food security, health, road safety). Perhaps actually in some cases it would be better to work structurally at a government level - after all, we know this works if implemented properly.
• There is an urgent need to undertake proper hazard mapping in many countries. It is a great shame that this is still not being done. It is also a tragedy that very skilled engineering geologists, with massive experience, are not being used by external agencies any more because of the low cost road ethos. This is a big mistake.

Finally, I do want to mention a presentation by one of my own PhD students, Katie Oven, who showed us how to give a clear and concise presentation on a very complex topic at an international meeting. She was in a class of her own.

So overall it was a great meeting with a terrific mix of people. I salute the organisers from the
Japan Landslide Society. I won't be at the World Landslide Forum, but if it is as good as this meeting then it will be one to remember.

Comments welcome!

Earthquake triggered landslide at Aratozawa Dam in Kurihara, Miyagi prefecture, Japan

Many thanks to reader Ripendra for alerting me to the following, and indeed for doing nearly all the work for this post. The 14th June 2008 earthquake in Japan is known to have triggered a number of landslides, as per earlier posts, but the most notable appears to have occurred at Aratozawa Dam in Miyagi prefecture.

The Aratozawa Dam (Figure 1) is a rockfill dam used for flood control, irrigation and hydro-electric power generation. It is 74.4 m high and 413.7 m long, impounding up to 14,130,000 cubic metres of water.

Figure 1: Miyagi Prefectural Government image of the Aratozawa Dam before the earthquake and landslide.

In the earthquake, a landslide occurred in the catchment of this reservoir. Professor Sassa of the International Consortium on Landslides has provided a brief description of this failure here:

"A huge landslide akin to a massive hole being punched in the side of a mountain was triggered by the Iwate-Miyagi Inland Earthquake at an upstream section of the Aratozawa Dam in Kurihara, Miyagi Prefecture, causing widespread damage and making roads impassable. Kyoji Sassa, head of the International Consortium on Landslides, said the volume of collapsed earth near the dam is believed to be more than 10 million cubic meters. Sassa believes that this is comparable to the largest landslides that occurred as a result of the 2004 Niigata Prefecture Chuetsu Earthquake, which also struck in a mountainous region, and to the volume that fell in single landslides after last month's cataclysmic earthquake in China's Sichuan Province.

"It may have been a 'deep landslide,' in which a large amount of earth completely collapses from a point deep in the mountain slope," Sassa said of the landslide set off by Saturday's quake. In such deep landslides, tremors that seem to thrust up from below cause the pressure of underground water to rise, making the ground above seem to float before abruptly collapsing.

Hiroshi Fukuoka, an associate professor at Kyoto University's Disaster Prevention Research Institute's Research Center on Landslides, said there was a complicated relationship between the landslide and the dam downstream of it. "Water is stored in the dam, and it seems that the underground water level rose and caused a high-speed landslide. Earth on the outside of the slope fell into the artificial lake behind the dam, bringing the danger of flooding," Fukuoka said. "It is necessary to establish whether such a risk exists when building a dam."

In many ways this description does not really do justice to the landslide that actually occurred, which is rather impressive. Figure 2, from Getty Images, provides a rather more helpful illustration of what occurred here:

Figure 2: Getty images picture of the Aratozawa Dam landslide.

Landslides from the 14th June 2008 "Iwate-Miyagi Inland Earthquake" in Japan

At 08:43:46 local time on Saturday 14th June 2008 a magnitude Mw=6.8 (USGS initial estimate) struck eastern Honshu in Japan. Although this earthquake (now being called the Iwate-Miyagi Inland Earthquake) was not particularly large, it occurred at a shallow depth (10 km) below an area that is quite mountainous. This is an areas that is very landslide prone anyway, being subject to active tectonic processes and frequent typhoon rainfall events. Once again, the consequences have been a large number of landslides.

Two days on some pictures are starting to emerge of the impact of the earthquake. The following three AP and Reuters images show quite well some of them:


The impact of all three on the road network us very clear - reports suggest that this has had a major effect on the rescue and recovery operations, as well as being responsible for a number of fatalities. The landslide in the first image is particularly interesting, but is slightly difficult to understand. Is this a large scale lateral spread?

Japan has a remarkable concentration of landslide specialists, so they are well-equipped to deal with this type of problem. Professor Sassa of the International Consortium on Landslides has commented on a large landslide at Aratozawa Dam in Kurihara, Miyagi Prefecture:
"Kyoji Sassa, head of the International Consortium on Landslides, said the volume of collapsed earth near the dam is believed to be more than 10 million cubic meters. Sassa believes that this is comparable to the largest landslides that occurred as a result of the 2004 Niigata Prefecture Chuetsu Earthquake, which also struck in a mountainous region, and to the volume that fell in single landslides after last month's cataclysmic earthquake in China's Sichuan Province. "It may have been a 'deep landslide,' in which a large amount of earth completely collapses from a point deep in the mountain slope," Sassa said of the landslide set off by Saturday's quake."

Meanwhile, the Daily Yomuri reports that:

"Eleven dams created by landslides that occurred when Saturday's Iwate-Miyagi Inland Earthquake hit are threatening to collapse, seriously affecting rescue efforts downstream. In response, the Construction and Transport Ministry on Sunday dispatched sediment control experts to the area to conduct a full-scale study on the possible danger posed by the so-called quake lakes building up behind such natural dams. According to the ministry, two quake dams have been confirmed on the Sanhasamagawa river and the Nihasamagawa river, five on the Hasamagawa river in Kurihara, Miyagi Prefecture, and four on the Iwaigawa river in Ichinoseki, Iwate Prefecture. Most of them stretch about 100 to 200 meters wide. Those rivers are feeders of the Kitakamigawa river. Once the water level rises and water spills out from a quake lake, its banks and the natural dam instantly collapse and a wave of mud could sweep into lowlands located downstream. "The danger of a collapse [of quake dams] changes all the time due to rain and aftershocks," a Construction and Transport Ministry official said. "We have to be very careful." The official said that the ministry plans to drain water from the quake lakes using heavy machinery to prevent a secondary disaster. There are some houses downstream of quake lakes on the Iwaigawa river. "Because we've got information that the water level is gradually rising, we may have to tell residents to evacuate depending on circumstances," an Ichinoseki municipal government official said.

They have rather a nice image of one of the sites. This is clearly not on the scale of Tangjiashan, but potentially hazardous nonetheless: