Sunday 23 April 2023

Eight confirmed deaths following landslide on the Pakistan/Afghanistan border.

Eight people have now been confirmed dead following a landslide close to the town of Torkham on the Pakistan/Afghanistan border on Tuesday 18 April 2023. The majority of the deceased are understood to be Afghan truck drivers who were cooking beside their trucks while waiting for a border crossing to open. The landslide buried about fifteen container trucks, carrying goods from Pakistan into Afghanistan, with several people being injured as well as those killed. Initial rescue attempts are understood to have been hampered by a fire triggered by the landslide crushing a gas cylinder used for cooking, while later in the week further problems were caused by heavy rainfall and a secondary landslide.

Rescue workers searching the remains of trucks destroyed by a landslide on the Pakistan/Afghanistan border on 18 April 2023. Rescue 1122 Khyber Pakhtunkhwa.

The immediate cause of the landslide appears to have been heavy rainfall falling in the area. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. Flooding and landslides are common at this time of year in northern Pakistan, where rising temperatures at the start of summer lead to thawing snow and ice in the mountains of the region. However the area does not typically receive large amounts of rainfall at this time of year, although such events seem to be becoming more common with the changing climate.

A huge landslide on the Torkham Export Road, close to the Torkham border crossing linking Pakistan and Afghanistan. Pakistan Armed Forces News/Twitter.

The Himalayan provinces of Pakistan are extremely prone to landslides, due to a number of active faults in the area, these being driven by the northward movement of the Indian Plate, which is pushing into Eurasia at a rate of 40 mm a year. This causes earthquakes on both plates, as well as the folding and uplift that has created the Himalayas and the Tibetan Plateau.

Block diagram showing how the impact of the Indian Plate into Eurasia is causing uplift on the Tibetan Plateau. Jayne Doucette/Woods Hole Oceanographic Institution.

However, the area around Torkham is not generally prone to large landslides, even at times of year when high rainfall is expected, suggesting that something else may have contributed to this event. Landslide expert Dave Petley has suggested on his blog that this may relate to road widening activity at the landslide site, which may have undermined a section of rock above an unconformity in the rockface, leading to a plane of weakness along which the rock could fail.

Google Earth images of the site of the Torkham landslide in 2016 and 2021. Dave Petley/The Landslide Blog.

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