7 October 2016
Cantata Memoria, in memory of the Aberfan Disaster
Later this month will mark the 50th Anniversary of the Aberfan Disaster in South Wales, the worst landslide disaster in British history and an event that has left an indelible scar on a generation. In brief summary, on 21st October 1966 a spoil heap of coal waste failed above the village of Aberfan. The resulting flowslide struck the village, and in particular the school, killing 116 children and 28 adults. Clearly I will post again on this topic in the fortnight ahead, and of course I posted about it five years ago. To mark the anniversary, the composer Karl Jenkins has written a new piece entitled Cantata Memoria. This is released by Deutsche Grammaphon today an\d will be premiered at a concert in the Wales Millennium Centre in Cardiff tomorrow.
Last Saturday, the Guardian ran a piece that provided some background to the composition of Cantata Memorium. The article is worth a read – in this extract Karl Jenkins explains the thinking behind the work:
Cantata Memoria: For the Children/Er Mwyn y Plant is both music and a poem. It is not a documentary, nor even a dramatisation, but it does include a conflation of ideas and facts that are by now part of the legacy. There wasn’t just one cortège (the title of a movement), but we do know that “All Things Bright and Beautiful” was sung at Pantglas School from time to time. A poignant line in the hymn has sinister ambiguity in our context as the “rivers running by” alludes to the hidden river running underneath the village that contributed to the disaster. The Welsh song “Myfanwy” (written by Joseph Parry from nearby Merthyr Tydfil and also quoted) was sung by the soldiers who dug for victims. “Myfanwy” was also the first piece performed by the local Ynysowen Male Choir, formed after the tragedy, and from which the community sought to find some solace.
The text is multilingual: English, Welsh and Latin (from the Mass), while also referencing words in many other languages which, it is hoped, symbolise how this memorial is at once both specific and universal.
Cantata Memoria, sung by Bryn Terfel among others, is in two distinct sections but performed continuously. The first deals with the disaster and its immediate aftermath, and the second moves from darkness to light, reliving memories and celebrating childhood.
There is a an extract of the work on the Classic FM website, and it should be viewable below:
It is haunting to the degree of being almost painful to me. It is a wonderfully fitting memorial to this most outrageous tragedy. It sits beautifully alongside the work by Laura Siersema, also written to remember the tragedy.
Other posts that may be of interest
- Landslides in Art Part 22: Aberfan (7 pianos, percussion, voice and tools of rescue)
- Remembering the Aberfan disaster – 45 years ago today
- Landslides in Art part 27: Louise Collis
- Landslides in Art Part 26: Robyn Collier
- Landslides in Art Part 25: Richard Humphrey
- Landslides in Art Part 24 – Mary Buckland
- Landslides in Art Part 23: Marzia Colonna
6 October 2016
Liukuo Hot Spring landslide
Earlier this week the Southern Cross Island Highway in Taiwan, one of only a small number of roads that cross the Central Mountains of Taiwan, suffered a major landslide at Liukou Hot Spring. This event was captured on a fairly dramatic video by road users. The video is contained within this PTS News report:
PTS News has a nice article about the landslide and its impacts, which indicates that about 150 metres of the road has been lost. The report also contains some nice drone images of the landslide that demonstrate its size:
The Southern Cross Island Highway in Taiwan is probably one of the most landslide-prone roads on Earth. Despite working in Taiwan for 25 years I have never yet managed a successful traverse without the way being blocked by a landslide. This Google Earth image illustrates the magnitude of the challenges:
Many of these landslides were triggered by Typhoon Morakot in 2009. Keeping this road open is a major challenge, but it is an essential access route for communities located in the mountains. That it is open at all is a testament to the engineers.
Similar posts that may be of interest
- Breaking news? Hundreds missing in Taiwan landslides after Typhoon Morakot?
- Typhoon Morakot mudslides: Before and after photos of Shiaolin (Hsiao-lin) village in Taiwan
- Eyewitness account of landslides triggered by Typhoon Morakot in Taiwan
- After Morakot
- Without doubt the most amazing landslide of the year so far – Pingtung County, Taiwan
- Landslides from typhoon Megi in Taiwan
- The mechanism of the Highway 3 landslide in Taiwan
- Images of the Highway 3 landslide in Taiwan
5 October 2016
Aletsch: a major developing glacial rockslide
Both Juy Bullot and Eric Bardou (many thanks to them) have alerted me to a very interesting major rockslide developing in the Aletsch region of Switzerland. Reports about the slide are only in French as far as I can tell, but this is a most interesting landslide.
The slide itself is at Moosfluh in the Riederalp, Canton du Valais, above the left flank if the Aletsch Glacier. This is a Google Earth image of the site, although note that the image is seven years old:
Le Nouvelliste has a brief article on the landslide (in French of course). this is my translation, with help from Google because I’m lazy!,:
A landslide in Moosfluh on the left bank of the Aletsch glacier has greatly accelerated in recent weeks. The hiking trails in the sector have been closed by the municipality of Riederalp with support from the canton. Numerous cracks and a few rockfalls have been observed at Moosfluh on the left bank of the Aletsch glacier. The phenomenon is being monitored in detail. The area concerned is about 1 square kilometre. The moving mass has a volume of more than 200 million cubic metres and is moving more than 20 cm per day.
A rapid collapse of the entire mass seems at this stage very unlikely.
They have this image of the site:
Rhone FM has a view from a different angle:
This is a wonderful opportunity to study the development of progressive failure in a large rockslope. Predicting the time of failure is fraught with difficulty, and it is good that no bold forecasts are being made at this stage. A particularly interesting aspect of this landslide is that its location is close to the terminus of the retreating Aletsch Glacier. Wikipedia reports that in some years this glacier is retreating at 100 m per year. It has long been hypothesised that major rockslides may be more likely when slopes are debuttressed by glacial retreat. That may be the case here.
Other posts on a similar topic
- Glacier Bay Landslide in Alaska: a satellite image and new videos
- Lamplugh Glacier rock avalanche: A massive new landslide in Alaska on Tuesday
- The Tyndall Glacier landslide: images from the University of Alaska Fairbanks
- The Tyndall Glacier landslide in Alaska: the largest recorded non-volcanic landslide in North America
- Dariali Gorge: another very large landslide from the Devdoraki glacier
- The Siachen Glacier avalanche (138 people killed) was an ice-rock avalanche
4 October 2016
The Sucun Village landslide in China
On Wednesday of last week a major mass movement, the Sucun Village landslide, was triggered by rainfall brought by typhoon Megi in Zheiang Province, eastern China. The landslide was in part captured in a remarkable video, although the clarity of the images is not particularly high. The amount of dust that this landslide generated is quite interesting.
Interestingly, the second part of this news report also appears to have a video of the landslide from a different angle:
The best image of the Sucun Village landslide that I have seen is this one, from JSChina:
According to Xinhua:
“Rainstorms triggered by Typhoon Megi caused about 350,000 cubic meters of debris to slide down nearby mountains, burying 20 houses in Sucun Village, Suichang County on Wednesday. More than 1,460 residents living nearby have been evacuated.”
I tracked the location of the landslide down to 28.778 N, 119.300 E, a location that has an excellent Google Earth image from 2013:
The key feature here needs no explanation of course – the site of the landslide had an active slide, perched high above the village, in 2013. Note the areas bare of vegetation between the slide and the town – close inspection suggests that these are areas of rockfall deposits. Note how close they are to the village:
The most depressing aspect of this landslide is the obvious progression to failure that the images display. This is the Google Earth image from 2010 – compare it with the one three years later. It is clear that the slope had evolved considerably. This should have been a warning sign:
This feels like a disaster that was avoidable.
On a similar note, I am deeply concerned about Haiti as it is struck by Hurricane Matthew. This large storm is a strong rainmaker. The biggest landslide disasters occur when tropical cyclones move slowly – and this one is doing exactly that:-
I blogged about the vulnerability of Haiti to hurricane rainfall right back in 2008. I wrote:
The landscape has little capacity to intercept and store water, and once flows across the surface begin the landscape rapidly erodes. The hills are clearly suffering from extreme deforestation. In September 2004, Hurricane Jeanne triggered mudslides and debris flows from these hills that killed over 3000 people in the city [of Gonaives]. Bearing in mind the fact that Haiti should be densely vegetated with tropical forest, the disaster that is the landscape in this country is all to clear to see. Unfortunately, posts about landslide disasters in Haiti will be a feature of this blog in the late summer for years to come.
Since then Haiti has suffered a major earthquake, and this is the first very extreme rainfall event since. The scene is set for a disaster, sadly.
Similar posts that might be of interest:
- Hurricane landslides in Haiti
- Deforestation, erosion and Cholera in Haiti
- Images of landslides triggered by the Haiti earthquake
- So just how bad was the debris flow at Barangay Andap during typhoon Bopha / Pablo ?
- Typhoon Bopha – a very real landslide threat for the Philippines
- Landslides in Japan from typhoon Talas
- Landslides from typhoon Megi in Taiwan
3 October 2016
The location of the Rizhao rockslide in Shandong
Over the last few days a number of people (see acknowledgements below) have sent details of the location of the Rizhao rockslide in Shandong, about which I posted last week. Please accept my apologies for the slow response – I have just completed an epic journey back from Wellington in New Zealand – which is about as far as you can go from Norwich without using a rocket – so I have a number of important landslides upon which to catch up this week (and thanks to those that have tipped me off about other interesting events). Watch this space. And, as an aside, I am deeply worried about the landslide potential of Hurricane Matthew as it makes landfall over Jamaica and Haiti, probably tomorrow. This has the potential to cause real problems – a direct hit on Haiti could be very nasty.
Anyway, the location of the Rizhao landslide is now clear. Strangely enough it turns out that it is not actually in Rizhao, but in Lanshan at 35.104° N, 119.325° E. This is a Google Earth image of the site from 2012 – clearly a lot of work has been undertaken since then:
Marc comments that:
My guess would be a large wedge style failure. Bedding is clearly visible and would be in a toppling geometry, but the failure plane appears to be on an inclined joint. In such an arrangement removal of material at the toe could provide a release mechanism.
This seems spot on to me. I remain surprised that this is described as a natural landslide when works had obviously been undertaken on the slope. And the image above suggests that this is a slope with a strong set of joints that had the potential to allow release of the landslide.
Similar posts that might be of interest with regard to wedge failures:
- Kalimpong Day 4 part 1: An interesting and deadly roadside landslide
- A major rockslide on US2 near Wenatchee
- The mechanism of the Highway 3 landslide in Taiwan
- Rockfall sequence in Yosemite
Thanks to Marc, Kirk and Jon Johnson, all of whom helped to track down the location of the landslide.
28 September 2016
Rizhao rockslide in Shangdong
The city of Rizhao in Shangdong, Eastern China has had an exceptionally lucky escape this week when a rockslide occurred in a new public park, shortly before it was due to open. The location is Phoenix Mountain in the centre of the city; the Park was due to open “later this month”. The rockslide itself is somewhat dramatic, as this image from The Nanfang shows:-
A view of the rockslide from a different angle looks no less dramatic:
According to the article, this slope had been turned into a rock climbing facility, and the area to the right of the landslide shows evidence of extensive slope engineering. I assume that this extended into the area that has failed, although it is not possible to say what it looked like. The failure itself appears to have been structurally controlled. Note the very large boulder sizes. Needless to say, if this landslide had occurred a month later the impact could have been very dramatic, with losses on the slope, in the park and in the parking area. The article makes some interesting observations about cause:
Zhang Bao, director of Lanshan District emergency services, said a preliminary investigation has determined that the landslide was a natural phenomenon, and not man made. However, Zhang did not answer questions as to why the park facilities are located so close to the mountain, or if any studies or investigations were conducted prior to the construction of the rock climbing facility.
That is a courageous conclusion in an area that has clearly had extensive slope works. Unfortunately as yet I have been unable to precisely locate this massif on Google Earth, so as yet cannot give an indication as to what this site was like before they works were undertaken. My best guess (and it is no more than that) is that it is this site, the image is from last year:
22 September 2016
Wye River: landslides in the aftermath of a forest fire in Australia
The small town of Wye River, on the coast of Victoria in the southeast corner of Australia, suffered devastating forest fires in the summer of 2015. Wye River itself lost 98 homes – one third of the town – and a further 18 were lost in nearby Separation Creek. Over Christmas last year a desperate battle was fought to save the remainder of the town, successfully, but images of the aftermath remain horrifying:
A well documented hazard in the aftermath of a large fire is the potential for increased landslides. Last week this area suffered heavy rainfall, triggering multiple landslides along the Great Ocean Road, which passes through the town (and can be seen in the image above). More than 150 landslides and rockfalls have been reported along the road in the last three weeks, and the highway remains severely restricted:
The most serious issue though is situated between Wye River and Separation Creek, where a landslide of about 1,000 cubic metres has developed, opening a large tension crack:
“The Paddy’s Path was impacted by a 35-metre tension crack and is posing a very significant landslip risk,” the EMV said, after VicRoads engineers inspected the path between Wye River and Separation Creek on Thursday. Wye River General Store’s Shaun McKinlay said the situation was “all too familiar” for residents, who faced the isolation of road closures, and the worry of not knowing what was going to happen next for the second time in less than 10 months. Mr McKinlay said on Friday he understood the crack becoming a landslide was an “event that’s going to happen, they just don’t know when”.
This is a GGoogle Earth image of the location of Paddy’s Path in Wye River:
This image shows the area burned in the fire of December 2015:
It is clear that the area affected by this landslide is exactly that burned in the fire last year. The link between the two is of course not a coincidence. That forest fires are becoming increasing problematic as a result of climate change is also well established in Australia. The implications for the future in terms of landslides are clear.
Similar posts likely to be of interest:
- Australian wildfires and risks of increased erosion rates
- Emergency assessment of wildfire debris flow potential
- AGU Day 4: Debris flows and the Station Fire [improved in light of comments from Susan Cannon]
- Mudslides occur in the areas affected by the 2009 Station Fire in Los Angeles
20 September 2016
The Canary Islands Megatsunami scare story
With frightening and depressing regularity the Canary Islands Megatsunami scare story rears its ugly head, to breathless headlines in the popular media. In case you need reminding, this is a scenario that involves a giant landslide from the flanks of the Cumbre Vieja volcano in the Canary Islands, which then generates a vast tsunami that sweeps across the Atlantic Ocean, causing untold devastation across a large area. It has been repeatedly debunked. This story reappeared this weekend in the Daily Star, which might not be considered to be a competitor to the Wall Street Journal, if you know what I mean. Inevitably the story is sensational:
Sigh! And of course it is accompanied with a map of the extent of the tsunami, with annotation to show just how big the impacts would be:
It is hard to know where to start with this as the story has been debunked so many times. So let me try to outline some of the key issues with the Canary Islands Megatsunami scare story:
- The generation of a tsunami on this scale requires a very specific landslide scenario. This is that the flank collapse occurs in a single enormous (we are talking 350 cubic kilometre) event and is extremely rapid. Hypothetically this is possible, but it is not likely. This is like saying that I’m worried that my house will be destroyed by a meteorite. It could of course happen, but it is so vanishingly unlikely that it is not worth considering. It is simply wrong of the newspaper to present an outlier scenario as one that seems likely.
- Studies of submarine volcanic flank collapse deposits suggest that they do not happen as a single coherent block, but instead as a series of slides. The resultant tsunami would be much less significant;
- The concept of “within three years” is a nonsense. Of course it principle could happen within three years – it could indeed happen tomorrow. Why three years? Not five? or 50? Or 3000?
- Most importantly, we know that this volcano, and many others, have undergone massive flank collapse in the past on multiple occasions. We even know that some have generated large local tsunamis. But large tsunamis leave a very distinct sediment footprint on the coast – tsunami deposits are well characterised and mapped, and no self-respecting geologist would miss a large one. And the megatsunami deposit from an event like that shown in the map above would be locally huge and would be present over a vast area. There is no way that such a deposit would be missed. But no such pervasive, recent, continent-scale tsunami deposit has ever been found. This indicates of course that none of the previous flank collapse events has generated a megatsunami on this scale, or even close to it. And I mean none of them – not from the Canary Islands, not from Hawaii, not from anywhere else. So, in some way, the potential flank collapse at Cumbre Vieja has to be fundamentally different from all that have gone before.
- And finally, even if Cumbre Vieja did collapse as hypothesized, the tsunami model described above would have to be right. Personally I find it hard to believe that a tsunami wave that is in effect generated by a point source and that has crossed the mid ocean ridge (and thus encountered comparatively shallow water) could generate a wave over 50 m high along a length of coastline thousands of kilometres long.
So does this mean that Cumbre Vieja can generate a large tsunami? Yes, of course. But is it even remotely likely beyond the local area? Absolutely not, in my view.
And of course aspects of this are silly from a risk perspective:
“Although Florida and the Caribbean would suffer the greatest destruction, with waves up to 164 ft smashing their coastlines, a weaker, but still massively destructive wave, is likely to batter Britain. It is thought thousands of people living in Britain’s southernmost coastal cities and towns, including Cornwall, Devon and Portsmouth, could be wiped out within hours, assuming no effective evacuation.”
“I would argue that they, their political overseers, and we the general public, should worry about the potential impacts of collapse generated tsunamis on a range of coastal nuclear facilities, ranging from power stations through nuclear reprocessing plants to dockyards full of decommissioned nuclear submarines.”
Frankly if a wave 50 metres high has just struck the entirety of the Eastern Seaboard of the USA and Canada, the Caribbean and the eastern coasts of Latin America; and a wave 100 m high has struck the western coast of Africa; and a wave has just wiped out western coasts of France, Portugal, Ireland, and the UK, all within six hours, then a wave 6 m high hitting Hinckley Point is going to be a pretty small part of the overall equation.
It really is time that this event was presented for what it is, which is an absolutely extreme scenario based on a very highly unlikely combination of events that is without precedent. There are lots of credible hazard scenarios that deserve our attention; this one does not.
19 September 2016
Piz Cengalo landslide video
On 11th September a significant rockfall occurred on Piz Cengalo, a peak located in the Swiss alps on the border with Italy in the canton of Grabunden. This is a peak that has had significant landsliding in recent years, most notably in 2011 when a large landslide involved about 1.5 million cubic metres of rock.
The landslide on 11th September was caught on video from a number of different angles. Probably the best was collected by Roman Christoffel:
This is an unusually clear video of such an event that captures in particular the transition from free fall to rock avalanche beautifully:-
The landslide was also captured from two other angles. This angle in particular is fabulous in the way that it shows the evolution of the rock avalanche and associated dust cloud:
Whilst this one shows the latter stages of the runout of the Piz Cengalo rock avalanche:
And finally a more distant view of the same event:
I cannot really think of another landslide that has been caught so well from so many different angles simultaneously.
Il Grigione Italiano has a nice article (in Italian though Google Translate does a good job) about the landslides. This suggests that the 11th September landslide on Piz Cengalo had a volume of about 100,000 to 150,000 cubic metres. As such this is small compared with the events of five years ago, and the runout meant that the damage was limited. Nonetheless, the authorities are clearly (and rightly) mindful of the continued landslide activity at this site and are maintaining the closure of some local hiking trails.
Posts on a similar topic:
- The Val Strem rockslide – a dramatic long run out landslide in Switzerland
- Wolhusen: an interesting river-blocking rockfall in Switzerland
- The remarkable Preonzo landslide in Switzerland last week
- The Randa rockslide – a spectacular new video
Thanks to my former student Dr James Glover for the heads up about this event.
8 September 2016
A Platform for Regional-Scale Earthquake induced landslide hazard assessment
Develop a planning and operational tool to forecast the number, volume and runout distance of landslides generated by different types and magnitudes of earthquakes in the varying materials and slopes around New Zealand.
Forecasting the location and size of earthquake-induced landslides as well as the distance they might travel down a slope are each complex process. Currently most approaches use statistical models, based on data from landslides triggered by past earthquakes located around the world. Many of these approaches focus on landslide susceptibility only, by identifying where landslides are more likely to occur in the terrain, rather than hazard, which also incorporates the downslope area affected by the debris should the landslide occur. In addition, few such statistical susceptibility relationships are calibrated to New Zealand geology and terrains. Many of the larger landslides triggered by recent earthquakes have a strong structural geological control and are not well predicted by the statistical models. A sub-component of this research will be to investigate relationships between geological structure, landslide-failure mechanisms and volume.
In this project, the PhD candidate would aim to address these issues by developing a computational GIS-platform to enable high-resolution regional-scale landslide hazard identification for different regions of New Zealand. This will comprise two components:
- A national probabilistic coseismic landslide hazard map (including runout), driven by the probabilistic seismic hazard model (PHSM) and with hazard related to susceptibility parameters calibrated with NZ and overseas landslide distributions and other information. This can be updated as the PHSM is updated, and will inform management of earthquake emergencies and other planning
- A rapid-assessment routine driven by the magnitude, location and depth, and shaking intensity of a specific earthquake. This will be based on 1 (above), and calibrated against known NZ earthquakes; it will inform initial response operations for a specific event.
The candidate will have access to new earthquake-induced landslide datasets captured for some recent earthquakes in New Zealand. The research is timely and will be used to develop the national New Zealand landslide forecast system being developed by GNS Science and others over the next five years.
We are looking for a PhD candidate so that we can apply for a fully-funded PhD scholarship, including University fees and living allowance. The candidate, if successful, would be enrolled at the University of Canterbury, New Zealand, and work in close collaboration with GNS Science and QuakeCoRE. The candidate would be expected to spend time in both Wellington and Christchurch, two of New Zealand’s more interesting cities.
If interested, please send firstname.lastname@example.org your CV before the 23rd September 2016.
Other blog posts of relevance regarding earthquake induced landslide hazard assessment in New Zealand:
- Sumner rockfalls – videos from the M=5.7 earthquake near Christchurch yesterday
- Rockfall and landslide damage in the Port Hills from the Christchurch earthquake sequence
- Port Hills, Christchurch: demolishing the rockfall threatened houses
- Rockfall risk assessment reports for the Port Hills, Christchurch, New Zealand
- Away from AGU – images of rockfalls as they occurred during the June 2011 Christchurch earthquake
- Images of landslides from the Christchurch earthquakes part 1: boulder damage to a house
- Images of landslides from the Christchurch earthquakes part 2: evil dancing boulders
- Images of landslides from the Christchurch earthquakes part 3: topographic amplification at the cliff tops
- Landslides from the Christchurch earthquakes part 4: large-scale cliff collapses
- Landslides from the Christchurch earthquakes part 5: landslides that involve sliding