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2 December 2022

BR-376: a deadly highway landslide in Brazil

BR-376: a deadly highway landslide in Brazil

On Monday 28 November 2022 a large landslide occurred on the BR-376 highway in western Brazil.  The image below captures will the aftermath of the landslide:-

The aftermath of the 28 November 2022 landslide on the BR-376 highway in Brazil.

The aftermath of the 28 November 2022 landslide on the BR-376 highway in Brazil. Image by CBMSL via MetSul.

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The image below, from the state news agency of Parana, shows the general set up of the slope that failed.  This image was collected after much of the debris had been removed from the slope:-

An alternative view of the aftermath of the 28 November 2022 landslide on the BR-376 highway in Brazil.

An alternative view of the aftermath of the 28 November 2022 landslide on the BR-376 highway in Brazil. Image by Albari Rosa / AEN via Parana Governo do Estando.

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There is a good gallery of images on the MetSul website.  Reports indicate that there were two failures.  The first occurred at about 3:30 pm on Monday, blocking one side of the BR-376.  Four hours later a second, larger, failure occurred whilst traffic was queueing to pass the spot.  This is the reason why so many vehicles were caught up in the failure.

At the time of writing two fatalities had been confirmed, whilst rescue operations continue.  Early fears were that there might have been as many as 30 fatalities, but thankfully this now seems unlikely.

The site was known to have stability issues, and reports indicate that work had been ongoing.   The failure was triggered by heavy rainfall – MetSul reports about 200 mm on the day of the failure.

I believe that the site of the failure is -25.874, -48.937.  This is the Google Street View image of the location, taken in March 2022:-

Google Street View image of the likely location of the BR-376 landslide in Brazil.

Google Street View image of the likely location of the BR-376 landslide in Brazil.

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It is notable that works were ongoing when this image was captured, although these appear to have been focused on a site a little further along the road.  The images in the aftermath of the landslide appear to show a temporary building (with a red roof), which is not present in the images from earlier this year.  Is this an indication of ongoing engineering works?

The rescue and recovery operations at this site are very complex.  Much of the debris and the vehicles are located off the road, below a large retaining wall.  Perhaps more importantly, there is a large displaced but stalled mass on the slope that is potentially unstable.  This is sufficiently large to pose a very substantial hazard to those in the debris field.

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29 November 2022

Cianjur: a deadly landslide from the 21 November 2022 West Java earthquake

Cianjur: a deadly landslide from the 21 November 2022 West Java earthquake

On 21 November 2022, a Mw=5.6 earthquake struck West Java in Indonesia.  The magnitude of the earthquake was comparatively low, but the event was exceptionally shallow (≈11 km), generating very high peak ground accelerations, albeit over a small but populated area.  At the time of writing it is estimated that at least 323 people were killed and over 62,000 homes were damaged.

In this environment. damaging earthquakes would be expected to trigger landslides.  Wikipiedia reports damage to roads and power infrastructure:

Landslides cut off roads.[28] A landslide along Puncak-Cipanas-Cianjur national road forced a traffic diversion. Toppled trees, uprooted power poles and downed power cables also occurred along roads.[29] The Ministry of Energy and Mineral Resources said two landslides occurred in Cugenang District. One measured 44 m (144 ft) and 16 m (52 ft) high while the latter measured 162 m (531 ft) and 45 m (148 ft) high.[30] A village in Cugenang with eight homes was completely buried under a landslide.[31]

The most spectacular landslide that I have seen occurred close to Cugenang, as noted above.  There are images of this landslide in a Tweet by GMA News, featuring images by Antara Foto/Raisan Al Farisi via Reuters:-

https://twitter.com/gmanews/status/1595347805232836609

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The second image is very revealing:-

Landslides close to Cugenang, triggered by the 2022 West Java earthquake.

Landslides close to Cugenang, triggered by the 2022 West Java earthquake. Image tweeted by GMA News, by Antara Foto/Raisan Al Farisi via Reuters.

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The location of the main landslide is -6.795, 107.079.  The image shows two other landslides, one just above the road on the far side of the main failure (also visible in the first image tweeted by GMA News), and the other on a bend in the river.  The material forming the landslides is deeply weathered and the failure at the head scarp is quite deep.  It is interesting that the crown of the landslide coincides with some buildings and a terrace.

It is not clear at present as to the number of other landslides that have been triggered by this earthquake, and clouds make satellite imagery hard to collect.  Some reports indicate that 18 bodies were recovered from a landslide, but I am unsure as to the particular failure to which this refers.

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28 November 2022

Casamicciola: drone footage of the deadly landslide at Ischia in Italy

Casamicciola: drone footage of the deadly landslide at Ischia in Italy

The deadly 27 November 2022 landslide at the town of Casamicciola Terme on the island of Ischia in Italy is now known to have killed seven people, whilst a further five remain missing.  Those confirmed to have died include a three week old baby and two other children. Four people were injured.  Rescue operations have continued through the night, but the prospects of anyone being recovered alive are low.

Ischia is a volcanic island with steep slopes.  Landslides have occurred on manyy previous occasions, and the risk has been greatly exacerbated by unplanned urban development in locations that are simply inappropriate.  Much of this development has occurred over the last three decades.

The most revealing imagery that I have seen of this landslide is a drone video that has been published on the 3B Meteo website.  It shows the full length of the landslide at Casamicciola.  This is the upper portion:-

A still from a drone video showing the 27 November 2022 landslide at Casamicciola in Italy.

A still from a drone video showing the 27 November 2022 landslide at Casamicciola in Italy. Drone footage by 3B Meteo.

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The path of the landslide has then run straight through the town.  The still below shows the section of the upper part of the urbanbised area with the landslide track:-

A still from a drone video showing the track of the 27 November 2022 landslide at Casamicciola in Italy.

A still from a drone video showing the track of the 27 November 2022 landslide at Casamicciola in Italy. Drone footage by 3B Meteo.

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The path of the landslide reached the sea in the lower part of the town, with vehicles and the remains of buildings being dumped into the water.

In Hong Kong this would be termed a natural terrain landslide.  The drone footage appears to indicate that it initiated on the very steep upper reaches of the slope as a comparatively small failure in weathered rock.  The channelised flow has then entrained large volumes of debris to generate a highly destructive flow.

In Italy, these types of events tend to generate a great deal of concern about the high levels of vulnerability to landslides.  I expect that there will be many statements urging the need to deal with the risk.  On previous occasions little action has actually been taken.

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23 November 2022

High resolution Planet Labs images of the Kusiong landslides in the Philippines

High resolution Planet Labs images of the Kusiong landslides in the Philippines

Earlier this month I posted Planet Labs PlanetScope imagery of the Kusiong landslides in the Philippines.  Rob Simmon has now acquired on my behalf a high resolution SkySat image of the area that shows the full extent of the devastation that the landslide have caused:-

Planet Labs SkySat image of the Kusiong landslides in the Philippines.

Planet Labs SkySat image of the Kusiong landslides in the Philippines. Image copyright Planet Labs, used with permission, captured on 12 November 2022.

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This is just a part of the area affected by the landslides – see my original post for the full extent.  In this area multiple shallow landslides can be seen, clustered on the slopes in the upper part of the catchments:-

Planet Labs SkySat image of a cluster of the Kusiong landslides in the Philippines.

Planet Labs SkySat image of a cluster of the Kusiong landslides in the Philippines.  Image copyright Planet Labs, used with permission, captured on 12 November 2022.

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In this image alone there are over 50 landslides.  Note that they are all shallow, that they originate high on the slope (which is likely to indicate failure driven by saturation caused by very intense rainfall) and they connect to the river system.  Thus, as I noted previously, this is a tragic, textbook example of shallow failures transitioning to channelised debris flows.

Elsewhere in the image the impact of the debris flows on communities is clearly visible:-

Planet Labs SkySat image of a destructive debris flow, part of the Kusiong landslides in the Philippines.

Planet Labs SkySat image of a destructive debris flow, part of the Kusiong landslides in the Philippines. Image copyright Planet Labs, used with permission, captured on 12 November 2022.

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Note the inundation of the houses and the damage to the land at this site.  It is notable that at the time of acquisition the road remained covered in debris.

The most serious damage, and many of the fatalities, occurred in a settlement on the upper slopes at 7.142, 124.088.  This is the location of the photograph that I originally posted.  The magnitude of the destruction at this location is laid bare in the imagery:-

Planet Labs SkySat image of the destruction caused by the Kusiong landslides in the Philippines

Planet Labs SkySat image of the destruction caused by the Kusiong landslides in the Philippines. Image copyright Planet Labs, used with permission, captured on 12 November 2022.

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Many houses were destroyed in this community.  Interestingly, Google Earth imagery from September 2019 shows no community at this site, and from December 2020 show just a small number of houses.

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Reference and acknowledgements

The images are from the wonderful people at Planet Labs.  Thanks in particular to Rob Simmon,

Planet Team (2022). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

 

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22 November 2022

Rubaya: at least 32 people killed in landslides in the Democratic Republic of Congo

Rubaya: at least 32 people killed in landslides in the Democratic Republic of Congo

There are various reports that landslides occurred in the towns of Rubaya and Bihambwe in the Masisi (North Kivu) part of the Democratic Republic of Congo on 18 November 2022, killing 32 people.  Of these 26 people were killed at Rubaya, whilst six were killed at Bihambwe.  It is not clear as to whether this was a single landslide that affected both sites, or two separate landslides.  Radio Kapi has an image of a large landslide, but again it is not clear as to whether this is the event that cost so may lives at Rubaya:-

A landslide at a mining site near to Rubaya in the Democratic Republic of Congo.

A landslide at a mining site near to Rubaya in the Democratic Republic of Congo. It is unclear as to whether this is the event that cost 26 lives. Image from Radio Kapi / Denise Lukesso

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The landslides were triggered by heavy rainfall, but appear to have been associated with illegal and/or unregulated mining activities.  Floodlist reports extensive flooding and landslides in the Democratic Republic of Congo since early November, including four deaths in Bunyakiri in the territory of Kalehe in South Kivu.

A freelance journalist, Baraka Munyampfura Héritier, has tweeted a short video of a landslide destroying houses in the area.  The interesting part happens in the first 15 seconds:-

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There is little information at present as to the circumstances of this event.

The mines at Rubaya are described in Wikipedia.  They appear to be focused on the extraction of coltan (tantalite), from which niobium and tantalum are extracted.  These mines are in the vicinity of -1.55828.884.  The Google Earth imagery of the area does not present a pretty picture:-

Google Earth imagery of the Coltan mines in the area of Rubaya in the Democratic republic of Congo.

Google Earth imagery of the Coltan mines in the area of Rubaya in the Democratic Republic of Congo.

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There is a lack of detail about landslides of this type in parts of Africa.  It seems likely that events are substantially under-reported.

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20 November 2022

Satellite imagery of the El Molino landslide in Norte de Santander, Colombia

Satellite imagery of the El Molino landslide in Norte de Santander, Colombia

The Planet Labs PlanetScope satellite instruments have captured imagery of the 10 November 2022 El Molino landslide in Colombia.  This is a cloudy area at this time of year, so obtaining images can be a challenge.  This is the site as of 11 November, with the track of the landslide clearly visible:-

The 10 November 2022 El Molino landslide.

The 10 November 2022 El Molino landslide. Planet Labs PlanetScope image, copyright Planet Labs, used with permission. Image captured 11 November 2022.

For comparison, this is an image of the same location on 3 October 2022:-

The site of the 10 November 2022 El Molino landslide.

The site of the 10 November 2022 El Molino landslide. Planet Labs PlanetScope image, copyright Planet Labs, used with permission. Image captured 3 October 2022.

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To allow comparison I have created a slider, which should allow you to see the site before and after the landslide:-

The 10 November 2022 El Molino landslide.The site of the 10 November 2022 El Molino landslide.

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There are two really interesting aspects of this site.  First, the landslide has picked out rather well the deforested area in the upper catchment.  I am unsure as to whether this indicates that the loss of vegetation may have been a factor or that there was a strong topographic control on both the farmland and the landslide.  I would tend towards the latter, but would be interested in views.

Second, it appears that there was an earlier, smaller but quite long runout landslide at this site, as shown in the October satellite image.  I have enlarged this below:-

The earlier landslide at the site of the 10 November 2022 El Molino landslide.

The earlier landslide at the site of the 10 November 2022 El Molino landslide. Planet Labs PlanetScope image, copyright Planet Labs, used with permission. Image captured 3 October 2022.

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The resolution of the imagery is not good enough to understand this slide properly.  It may well have played a role in the development of the main failure.

Meanwhile, as of three days ago the five victims of the landslide had not been recovered, and there is concern about the damming of the river as well as about the potential for a further landslide.  A small lake has developed.

The landslide destroyed 670 hectares of land, whilst 130 people have been rendered homeless.

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Reference and acknowledgements

The images are from the wonderful people at Planet Labs.

Planet Team (2022). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

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16 November 2022

Mizoram: a deadly quarry rockslide caught on video

Mizoram: a deadly quarry rockslide caught on video

On 14 November 2022 a significant rockslide occurred at Maudarh in Hnahthial district, in Mizoram, India.  Tragically, 12 workers were caught up in the landslide, alongside five excavators, a stone crusher and a drilling machine.  To date 11 bodies have been recovered; it is highly unlikely that the other victim will be recovered alive.

The event was captured on video – I was made aware of this in a tweet by SANDRPThe video is on Youtube:-

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India Today has a photograph of the aftermath of the landslide:-

The aftermath of the 14 November 2022 landslide at Maudarh in Mizoram.

The aftermath of the 14 November 2022 landslide at Maudarh in Mizoram. Image from India Today.

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The image below shows one of the first frames from the video of the landslide:-

The early phases of the 14 November 2022 landslide at Maudarh in Mizoram.

The early phases of the 14 November 2022 landslide at Maudarh in Mizoram. Still from a video uploaded to Youtube.

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The landslide appears to originate in residual soil high up on the slope above the quarry.  As both images above show , the landslide debris involves mostly weathered rock, although the video itself shows some failure of the rock that was being quarried too, especially on the right hand side.  So, a provisional interpretation might be that the quarry operations had not removed enough of the weathered material high up on the slope, which then failed due to the loss of toe support.  The debris then triggered some failure of the rock being quarried in the lower part of the slope.

It is interesting that the weather was sunny and dry at the time of the failure.

In general investigations of landslides like this conclude that they were avoidable accidents.  The quarry at Maudarh in Mizoram, which is being used to extract stone for the construction of a new national highway in the area, appears to be located at 22.915, 92.893.  A quarry at that location is visible on satellite imagery.

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15 November 2022

The impact of the Williamson Diamond Mine tailings breach

The impact of the Williamson Diamond Mine tailings breach

The high resolution Planet Labs SkySat satellite image of the Williamson Diamond Mine tailings dam breach, which I featured last week, also shows the impact of the mine waste on downstream communities.  This image shows the inundated and overtopped dam downstream of the tailings storage facility (TSF).  At the site of the spillway to the north, now filled with tailings, there is a small community that has been heavily affected by the waste:-

The impact of the mine waste plume from the Williamson Mine tailings dam failure.

The impact of the mine waste plume from the Williamson Mine tailings dam failure. Planet Labs SkySat image, copyright Planet Labs, used with permission. Image captured 9 November 2022 at 11:21 UT.

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Further to the northeast there is another set of properties affected by the tailings:-

The impact of the mine waste plume from the Williamson Mine tailings dam failure.

The impact of the mine waste plume from the Williamson Mine tailings dam failure. Planet Labs SkySat image, copyright Planet Labs, used with permission. Image captured 9 November 2022 at 11:21 UT.

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For these households the impact of the mine waste will have been devastating.  Reuters reports that 13 households have been displaced, whilst mining operations have been suspended for three months pending an investigation into the causes of the disaster.  The incident is being investigated by the National Environment Management Council (NEMC) in Tanzania.  Petra Diamonds itself has a statement on its website dated 10 November 2022, which includes this:

Impact on the environment and local community

From an initial assessment, supported by the use of satellite imagery, the main portion of the tailings have been contained by the New Alamasi water dam which sits within the Mine Lease Area to the north east of the TSF. A portion of tailings has flowed around the dam into a tributary to the north of the New Alamasi water dam. Flow below the dam consisted mainly of water and was largely contained by the topography.

[Williamson Diamonds Limited – WDL] WDL is working closely and collaboratively with local, Regional and National authorities to assess the environmental damage and to  put in place and implement remediation plans as soon as possible. WDL and Petra appreciate the prompt response and assistance that has been provided by these authorities.

A total of 13 dwellings have been affected and the emergency response teams’ immediate priority has been to provide accommodation and humanitarian aid to those affected. A socio-economic survey has been initiated, supported by an external social impact specialist, to determine additional social impact. Extensive and ongoing engagement with communities will continue to take place, together with the Government, to ensure that key stakeholders are kept appraised of WDL’s response, including planned remediation activities.

I will leave it to the reader to judge as to whether they feel that this is an adequate response to an accident of this scale.

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Reference and acknowledgement

Thanks to Rob Simmon at Planet Labs for acquiring and posting the image.

Planet Team (2022). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

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14 November 2022

El Molino: a very large landslide in Colombia

El Molino: a very large landslide in Colombia

On 10 November 2022 a large landslide occurred at El Molino in Villa Caro, Norte de Santander in Colombia.  Landslides are increasingly common in Colombia, but this is an unusually large event.  Caracol has an article in Spanish about the landslide, whilst Semana has this before and after image of the site:-

Before and after image of the landslide at El Molino in Colombia.

Before and after image of the landslide at El Molino in Colombia. Image from Semana.

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It is very difficult to appreciate the scale of this landslide from photographs, but Noti Cucuta has tweeted this helicopter footage of the aftermath of the event:-

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There is also another video that has been tweeted by Diario La Opinión:-

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And Segunda División del Ejército Nacional has a further helicopter video, which shows the long runout of the landslide:-

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The landslide was triggered by prolonged heavy rainfall.  It has resulted in 28 families being rendered homeless, and five people from a single family are reported to be missing, presumed to have been killed.

This landslide is quite reminiscent of the 16 December 2017 Villa Santa Lucia landslide in Chile.  I will need to use satellite imagery to understand it properly.  The landslide was captured on a Planet Labs image on 11 November 2022, so this will be possible in the coming days.  The crown of the landslide is at 7.949, -73.025.  It has a total runout distance (crown to toe) of about 5 km.

I will provide more details in the coming days.

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10 November 2022

High-resolution SkySat imagery of the Williamson Mine tailings dam breach

High resolution SkySat imagery of the Williamson Mine tailings dam breach

My good friends at Planet Labs have very kindly captured a high resolution SkySat image of the aftermath of the major Williamson Mine tailings dam breach in Tanzania.  I will post further images over the next few days.  To start off, the image below shows the site of the breach itself:

The breach that caused the Williamson Mine tailings dam failure.

The breach that caused the Williamson Mine tailings dam failure. Planet Labs SkySat image, copyright Planet Labs, used with permission. Image captured 9 November 2022 at 11:21 UT.

The breach is large as I noted yesterday.  It appears that some of the original tailings wall material, including intact blocks, have been deposited on the downstream edge of the breach, especially on the south side.  There appears to be a step in the tailings at the site of the breach, suggesting a lower layer of denser tailings.  This indicates that further releases could occur in rainfall.

The tailings that have escaped appear to have been very fluid – note the flow patterns in the sediments.

I can see so signs of any works occurring at the site to manage further releases. Indeed, there are no vehicles or people visible in the image, as far as I can tell.

The SkySat image has also captured the downstream impacts of the tailings dam breach.  This is the tailings plume:-

The mine waste plume from the Williamson Mine tailings dam failure.

The mine waste plume from the Williamson Mine tailings dam failure. Planet Labs SkySat image, copyright Planet Labs, used with permission. Image captured 9 November 2022 at 11:21 UT.

The images show that the plume hit a water retention structure downstream from the mine, filling the reservoir.  Some tailings appear to have overtopped, but most have followed the spillway to the north, inundating the basin of an incised channel.  I will try to post further imagery of this area in the coming days.


Reference and acknowledgement

Thanks to Rob Simmon at Planet Labs for acquiring and posting the image.

Planet Team (2022). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

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