15 April 2016
Colonnata: a large collapse in a Carrara marble quarry in Italy
Firefighters were searching for two quarry workers missing on Thursday after a wall of rock at a quarry in the Apuan Alps collapsed. A third quarryman who was reportedly left hanging by a rope in the quarry in Tuscany’s Colonnata basin was rescued and taken to hospital. Another worker was taken to the quarry’s own first aid centre after feeling ill due to shock.
In this age of global news, the Shanghai Daily has the most detailed report that I can find in English.
The accident happened in a large quarry in the Apuan Alps, a mountain range in Tuscany region which contains immense deposits of marble, named “marble of Carrara” after the name of a nearby city, and considered as one of the most precious marbles in the world. According to first reconstructions, the three men were on top of a mountain to check the marble cutting when a wall of rock, almost 2,000 tons of marble, suddenly crumbled, and two of them who were not wearing a harness fell down for about 30 meters along with their cutting machine. The two quarrymen, aged 55 and 46, were reportedly buried by marble slabs and other debris.
The Corriere Fiorentino site has a gallery of images of the rockfall at Colonnata, including this overview of the deposit:
Paolo Forlin, who leads the amazing ArMedEa project, pointed out this tragic accident to me. He also highlighted an extraordinary short film about the abseilers who enable the quarrying operations for Carrara marble. The film is in Italian but there are English subtitles. With a bit of luck you should be able to view this below (apologies for the advert – I cannot avoid this):
Carrara marble is a prized stone worldwide. Michalangelo carved his famous sculpture of David in Carrara marble, and buildings constructed from it include the Pantheon in Rome, the Marble Arch in London, the Harvard Medical School buildings and Oslo Opera House. I suspect that few people realise the human cost of this most beautiful rock.
13 April 2016
Landslide damage to the Karakoram Highway
The Karakoram Highway has been closed for traffic since 2nd April, the day torrential rainfall triggered hazards wreaked havoc across the Gilgit-Baltistan region, killing 16 people, mostly in the Diamer District. The Karakoram Highway was blocked at more than a hundred locations, which has now been cleared for most part, save for two major blockades in the Kohistan District of KPK. A portion of the KKH was completely destroyed by a landslide in the Chuchang area of Dassu, Komila, while a major landslide blocked the treacherous highway in Kiyal area…The government of Gilgit-Baltistan has said that opening the road for traffic can take up to one more week.
After the rainfall reports suggest that the highway was blocked in over 200 places by landslides, but most of these have now been cleared. However, the remaining blockages do seem to be extremely serious. This is the landslide at Chuchang (sometimes spelt Chochang), posted to the twitter account of Wasif Shakil:
The challenges of clearing this landslide, and making the road safe, are clear. The Pamir Times article has an image of the attempts to create a new road across this landslide:
The other site appears to be at Kiyal. Gilgit News Time posted images of this landslide on 8th April:
Given that the slide surface is solid rock and passes through the level of the road this is going to be extremely challenging to repair quickly.
The impact of these closures is serious. The Pamir Times reports shortages of food and fuel, with many areas also without electricity. But perhaps the biggest impact of the landslides is on the irrigation system:
The lands across Gilgit-Baltistan are irrigated by using glacial water brought to the human settlements by digging channels through vulnerable mountain sloped and rocks. These water channels have been damaged to a very large extent across the region, posing a serious threat to the livelihood means of thousands of farmers.
In a landscape that is genuinely astonishing, these channels are incredible feats of engineering. This is an example, cutting across a steep, unstable rock slope. that I photographed in Gilgit in 2010 when I was working on Attabad:
The loss of these channels, and the work that will be needed to restore them at a key point in the agricultural year, is very significant.
12 April 2016
The Renfrew County Landslide
At about 2 am on 29th March 2016 the Renfrew County landslide occurred near to Horton Township, west of Ottawa in Canada. This landslide, which is reported to have had a surface area of 10 hectares, slipped into and blocked the Bonnechere River. Various local news agencies have images, of which the best overview is on the Ottawa Citizen:
The level of the impounded water rose by 7 m, damaging a cottage, a hunting camp and a hydroelectic plant, amongst other impacts. After about seven hours the dam breached, releasing a flow at a rate of about 250 cumecs (cubic metres per second).
“There are definitely ancient, large landslides that are mapped in that area,” said Greg Brooks, a landslide expert with Natural Resources Canada. “This is another one…You can’t stop them. When they’re going to happen, they’re going to happen.” He said the land includes a lot of leda clay — the former bottom of the ancient Champlain Sea, which is prone to collapsing suddenly, especially when it is sodden. Early spring, while the ground is thawing, is prime time for these landslides. The size, though dramatic, isn’t a surprise, Brooks said. “Sensitive clay landslides can easily be that size, or larger.”
This appears to be the site of the landslide:
That bulge into the river might be the sign of some previous instability perhaps?
The best information and data about the landslide sits on the Twitter account of James Power, a Paramedic Drone Consultant (who knew there was such a job?) with Renfrew County Paramedics. His twitter handle is @IASF07. He, and his colleague Steve Osipenko (@osipenko_steve) have tweeted some great images and videos of the landslide, taken by his drone, including this photograph:
11 April 2016
The Tyndall Glacier landslide: images from from the University of Alaska Fairbanks
On 17th October 2015 the huge Tyndall Glacier landslide occurred on the flanks of Taan Fjord in Icy Bay in Alaska. I featured this landslide, which was detected via the seismic detection system developed by Goran Ekstrom and Colin Stark, in a blog post at the start of the year. This is the largest recorded landslide in North America, with a volume of about 72 million cubic metres and a mass of about 180 million tonnes. The landslide generated a large tsunami that caused extensive damage along the flanks of Taan Fjord. However, until now it has not been possible to get a good impression of the impacts of this event as the area has been covered in snow.
Chris Larsen from the Geophysical Institute of the University of Alaska Fairbanks has flown along Taan Fjord, and a press release has provided two images of the site and the effects of the displacement wave. So, first, this is an image of the landslide scar:
On the right side of the image some of the damage caused by the displacement wave is visible. This is much more clear on the other image released:
The removal of trees and the topsoil as the wave traveled down the bay is clear. In the press release, Chris Laren is quoted as saying:
“It almost blows away everything in the historical record except for Lituya Bay…It’s really a unique event to have a tsunami 100 meters high.”
The press release finishes as follows:
Icy Bay and places like it will have more landslides as time goes on, Larsen said. Warmer temperatures melt more glacial ice that buttress hillsides. When the ice melts, oversteepened slopes will fail. Sometimes it takes a big rain or an earthquake to shake them down. “These megatsunamis are infrequent in the historical record but will most likely increase,” Larsen said.
We live in interesting times.
7 April 2016
Five new landslide videos – two dashcam films from China, two rockfall films and a video from GNS about earthquake triggered failures
Three new landslide videos – two dashcam films from China and a video from GNS about earthquake triggered rockfalls
1. A dashcam film of a large landslide from China:
2. A dashcam video of a landslide near to Guilin in Sanjiang Dong Autonomous County, Guangxi, China
There is a little more information about this one. It is less dramatic, but still interesting. The driver was clearly rather wise in choosing not to proceed and pick his/her way around the rocks in the road. This illustrates one of the hidden perils – the precursory falls cause vehicles to slow down, which means they are in danger for much longer:
The full description from Youtube is as follows:-
Torrential rain over the Qingming Festival three-day weekend has triggered landslides in south China’s Guangxi Zhuang Autonomous Region. Footage shot by a car’s dashcam shows the moment a landslide took place on an expressway in Sanjiang Dong Autonomous County on Monday. Realizing the danger of the situation ahead, the car driver and a passing van stopped just in time and hurriedly reversed their vehicles.
3. What is it like to be caught in a rockfall?
The answer is truly terrifying. This was published on Youtube on 30th March. It occurred in Ancash, Huaraz in Peru:
This could have had a terrible ending.
4. A big toppling failure from India
This apparently happened in the Pangi Valley in Himachal, India. There is no time stamp:
And finally, a video from GNS Science about their response to the most recent Christchurch earthquake
This is a very nice video about how Geonet / GNS Science responded to the Valentines Day earthquake in Christchurch. The first part of the film features the rockfall team, including my friend and former student, Chris Massey.
5 April 2016
Heavy rainfall brings extensive landsliding to Kohistan and other parts of northern Pakistan
In the last few days another belt of exceptional rainfall has swept across northern Pakistan, including Kohistan, triggering large numbers of landslides as well as avalanches and floods. The most destructive incident appears to have occurred at Othar Nala village in Kandia, Kohistan district, where a large landslide destroyed a number of houses. It has been widely reported that 14 bodies have been recovered from the ruins, together with 13 injured people. Reports vary on the number still missing, but 24 people seems to be the most likely number. If so, with a probable final toll of 38 people, this is a significant event.
Elsewhere across Khyber-Pakhtunkhwa there are multiple reports of landslides, as well as house collapses and floods. One report for example is of two girls being killed in a flash flood or debris flow Hattian Bala, 50 km from Muzaffarabad. Hattian Bala was the site of the largest landslide, a giant rock avalanche, triggered by the 2005 Kashmir earthquake. The landslide dam subsequently breached in a large rainfall event.
The most graphic illustration of the impact of these rains lies on the Pamir Times website, which has an excellent photo report of landslides on the new section of road built with Chinese assistance to bypass the Attabad landslide in Hunza. These tunnels were opened last year. These two images show the magnitude of the problems:
Whilst the damage from the landslide in the second image is less obvious than in the first, I have concerns about the material that this tunnel is built upon and is crossing. Is this an old landslide?
There are reports of many other landslides blocking the Karakoram Highway.
1 April 2016
Landslides in Art Part 25: Richard Humphrey
Richard Humphrey began his formal art education at the Art Center College of Design in Los Angeles in 1972. He then joined the staff of the Aerospace Corporation as a graphic designer, which provided him with a comprehensive background in design, illustration, and computer graphics. As a fine artist, Humphrey has focused on painting en plein air, concentrating on the area in which he was raised, California’s Palos Verdes Peninsula. Since 1997, Humphrey and fellow local artists have created hundreds of paintings to benefit the Palos Verdes Peninsula Land Conservancy in the preservation of the still undeveloped acreage in the area. California Museum exhibitions include: The Autry National Center, the Natural History Museum of Los Angeles County, the Bowers Museum in Santa Ana, the Carnegie Art Museum, the Pasadena Museum of History, the Pasadena Museum of California Art and the State Capitol Building in Sacramento. He is a Founding Member of the Portuguese Bend Artists Colony and a Signature Member of the California Art Club, where he was awarded the Edgar Payne Award for landscape painting in 2007.
The work I am featuring is a watercolour entitled ““Morning at Bluff Cove”, which was selected for the California Art Club’s 105th Annual Gold Medal Exhibition:-
The location is, I think, Bluff Cove on the Palos Verdes Estates Shoreline Preserve in California. The bluffs of this section of coastline are renowned for active landslides. The painting captures beautifully two examples. On the leff the landslide appears to be a shallow translational slide, whilst on the right is a deeper seated landslide, perhaps with an element of rotational failure.
31 March 2016
Pakistan: a highly destructive landslide caught on video
A new video has appeared on Youtube and Liveleak showing a landslide in Pakistan. The slide appears to have started high up on the slope, but unfortunately the video quality is not good enough to ascertain properly what is happening. It appears to accelerate rapidly down the lower slopes – but see below because the mechanism is more complex than it appears – and then crashes through a series of houses:-
Taking a look at the video in a little more detail, clearly before the landslide appears on the lower slopes something is going on in the plateau area beyond the view of the camera. The people around the camera were aware of this, and appear to be trying to warn those on the slopes below of the danger. There is a lot of dust in the air at the top of the slope:-
It looks to me like the slope above the plateau is failing and moving, but it is hard to tell. Could this be a quarry?. About 27 seconds into the video, material starts to travel over the break of slope that marks the edge of the plateau, and it travels down the main slope. Compare the image below with the one above:-
But what happens next is the most interesting element. The debris flowing down the lower slope triggers another failure, probably in the deep soil and weathered rock that forms this area. This is just happening in the still below:
It is this secondary failure that destroys the houses, leaving the deep landslide scar behind:-
Technically this is a combination of an induced failure and a rapid entrainment event. It illustrates beautifully the complexity of landslides, and why it is so hard to forecast their behaviour.
Sadly there is no further information about this landslide – does anyone know any more?
30 March 2016
Rockfall triggering on warm days in exfoliating landscapes
Rockfall triggering is a complex process. It is an interesting intellectual problem with which to grapple – what causes a block to detach at a specific moment in time? Whilst the obvious suspects are of course water and wind; a less blatant factor is the growth of ice within a fracture or joint that can slowly widen the crack until detachment occurs. And of course we know earthquakes are a key issue in those areas that are seismically active, but in many ways that is a different problem.
In the literature there are some suggestions that heating from the sun might also be a factor in landscapes subject to exfoliation. For those who need a reminder, exfoliation occurs when the stress system allows joints to form that run parallel to the rock surface, allowing sheets or slabs of rock to detach. There is a good explanation of this process on the Geological Society webpage, although in my view this overplays the role of chemical weathering. However, the evidence for the strength of this thermally-driven process is not good, so its importance has been hard to judge.
Yosemite is a landscape dominated by exfoliation, creating spectacular landscapes and frequent, potentially hazardous, rockfalls. As such this is an ideal place to study thermally-driven crack widening in an exfoliating landscape. In a paper just published by Nature Geoscience, Brian Collins and Greg Stock (Collins and Stock 2016) have investigated this process by monitoring, over a period in excess of three years, the displacement of a crack forming a large exfoliation joint in Yosemite. This is excellent work using high precision crack meters, and sensors for other environmental conditions, shown below in a figure from the paper:
The results are fascinating. Collins and Stock (2016) show clearly that there is a strong daily cycle of temperature variation on the exfoliation surface as the block is heated by the sun. In response, the crack widens, before narrowing again as the rock block cools back down:
But the most exciting element of this is that a component of the deformation is permanent – i.e. at the end of each cycle (each loop in the figure above) the crack is a little wider. In fact the amount of permanent deformation in each cycle shown above is remarkably high – in the order of a millimetre on each occasion. This level of permanent damage will only occur under ideal situations – i.e. in the middle of summer (note the date above in relation to the solar cycle) on a near cloudless day, but nonetheless the role of solar heating in causing permanent displacements in exfoliating landscapes is clear. It is also worth noting the magnitude of the daily displacements, which are in the order of a centimentre. This is a remarkably dynamic environment.
These results are scientifically wonderful, and they have implications for landscape evolution and rockfall hazards in other high mountain areas. Whilst higher than expected levels of rockfalls have been observed in the summer months in many mountain landscapes, in general I think it has been assumed that this is mostly associated with the melting of ice in cracks. Whilst this ice driven process is undoubtedly still important, Collins and Stock (2016) has given us cause to think about other processes too.
Collins, B.D and Stock, G.M. Rockfall triggering by cyclic thermal stressing of exfoliation fractures. Nature Geoscience. http://dx.doi.org/10.1038/ngeo2686
29 March 2016
Sparmos Dam – a significant dam failure in Greece on Sunday 27th March
In Elassona, Greece the Sparmos Dam overtopped and breached in the afternoon of Sunday 27th March. Geotechpedia has a short article with some images. There is a better set of images on the Michanikos.gr website. An edited Google translation of the description is as follows:
Thousands cubic meters of water poured onto the plain of Elassona, destroying roads and fields with crops when the Sparmos dam broke on Sunday. The surge of water, indeed, was such that it even dismantled the pavement.
The breach in the dam itself is quite dramatic:
Fortunately downstream damage appears to be light. Note the shallow landslide on the inner face of the dam wall, on the right side of the embankment. I suspect that this is a drawdown landslide, triggered by imbalanced high pore water pressures in the embankment when the water level rapidly dropped. Michanikos.gr also has a close up of the breach itself:
It seems fortunate that the damage was not more serious. EPT reports (in Greek) that there are plans to rebuild the damaged portion of the dam to restore its capability to store water. It seems important to understand first how the overtopping event occurred.