Landslide problems on roads in Vietnam

The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.

On 13 July 2024, a terrible landslide occurred on a road in the mountainous province of Ha Giang in Vietnam. A minibus travelling along a road in Bac Me District at 4 am was struck by a landslide. Eleven people were killed and a further six were critically injured. The failure was large – 50,000 m³ is the estimated volume – and of course the timing (in darkness when escape is very difficult) was terrible.

Nguyễn Tất Thắng has posted a video of the landslide site on to Youtube:-

This includes the view below of the site:-

The failure appears to have occurred in deeply weathered soil / regolith. Note the quite planar back scar, and the deep-seated nature of the main scar. The terrain is steep, so the landslide has had quite high mobility.

An interesting aspect is that the landslide occurred on a sharp bend in the road, which makes me suspect that the toe of the slope might have been cut quite intensely to create the space for the bend. The area around the main landslide scar has also been cleared of he natural woodland.

The landslide, which occurred in heavy rainfall, has brought into focus concerns about the safety of mountain roads in this part of Vietnam. VNExpress has published a really good pictorial article about this issue, which includes images and videos of the problems along a variety of roads. The article highlights a wide range of issues, including the failure of slopes below the road level, sometimes associated with river erosion and sometimes with fill slopes; rockfalls from cut slopes; and landslides in deeply weathered soil and regolith.

All of these failures are avoidable with good quality engineering, although I recognise the challenges that this poses. As rainfall intensities continue to increase, the problems in these mountain environments are getting steadily worse in many places. In the last few days alone, we have seen the dreadful landslide on a road in Nepal, which killed over 60 people; the landslide in Vietnam highlighted in this post; and today a landslide on a road in Karnataka in India, which is believed to have killed ten people.

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