19 April 2023
Torkham – a large rockslide in Pakistan
Posted by Dave Petley
Torkham – a large rockslide in Pakistan
On 18 April 2023, a large rockslide occurred at Torkham in Pakistan, very close to the border with Afghanistan. The landslide, which occurred in the early hours of the morning, struck a line of trucks waiting to cross the border. It is thought that about 20 trucks were buried in the accident. At the time of writing, three people are known to have been killed and a further eight people have been injured. Rescue operations continue, led by the army.
The best image that I have found of this landslide has been tweeted by Pakistan Armed Forces News:-
The 18 April 2023 landslide at Torkham in Pakistan. Image tweeted by Pakistan Armed Forces News.
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The image shows a rockslide – based upon the scar it appears that the landslide has mobilised a set of discontinuities inclined parallel or sub-parallel to the slope. The debris appears to have bulldozed the trucks, and there is some evidence of the aftermath of a fire. Rescue operations will be very challenging as the boulders are large and of course removal of debris at the toe risks creating instability in the debris pile.
The location of the landslide is [34.115, 71.102]. This is a Google Earth image of the landscape, collected in October 2021:-
Google Earth view of the site of the 18 April 2023 landslide at Torkham in Pakistan.
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Of interest here is the indication that the toe of the slope has been cut as part of construction works. By comparison, here is an image from 2016:-
Archive (2016) Google Earth view of the site of the 18 April 2023 landslide at Torkham in Pakistan.
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I have created a slider to allow the two images to be compared:-
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It is unclear as to what has happened at the site since 2021 – there may be some evidence of the creation of concrete structures for the road – but a reasonable starting hypothesis could be that the cutting of the toe has enabled the instability.
News reports indicate that the landslide was triggered by a lightning strike. In most cases, such reports are erroneous, with the actual trigger being the very rainfall that accompanies the thunderstorm.
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
The slope to the left also looks problematic. Possibly it is starting to move and develop a tension crack. But it could be the different lighting. Certainly a problematic area with the daylighting wedding planes.
Any idea of the bedrock type? First glance to me said “exfoliation slabs”. If plutonic with a high quartz content, a lightning strike isn’t unreasonable. Quartz has piezoelectric properties (will flex when voltage is applied, and visa versa), and (more likely) the heat of a strike could’ve made the rock expand and converted whatever water was in the joints to steam instantly.