Between 4 and 6 August 2023, intense rainfall triggered at least 346 landslides in the area around Ho Bon commune in Mu Cang Chai district, Yen Bai province in Vietnam
I have written frequently on this blog about clusters of rainfall-induced landslides. Another really interesting example has been highlighted in a paper (Toan et al. 2025) in the journal Landslides. Between 4 and 6 August 2023, intense rainfall triggered at least 346 landslides in the area around Ho Bon commune in Mu Cang Chai district, Yen Bai province in Vietnam.
Frustratingly, the paper does not give a lat / long location for this event (it continues to amaze me that this is not mandatory), but I believe the location is: [21.87657, 103.91738]. The exact nature of the rainfall event that triggered these landslides is uncertain as the loacl rain gauge was destroyed during the event. However, in the hour before the loss of data (6-7 pm on 5 August 2023), the rain gauge recorded 62.6 mm of precipitation.
The two Planet Labs images below show the outcome. The first was collected on 22 May 2023, before this event:-
The marker is situated on Ho Bon commune. And this is the aftermath of the event:-
This image highlights the landslides to the south of Ho Bon commune:-
Toan et al. (2025) do not claim that their mapping is comprehensive – and I think this is right as there appears to be more failures in the imagery than they have described. They note that the majority of the landslides that they mapped were debris flows, but I would probably characterise most of the failures in the imagery as shallow, disrupted landslides. They note that areas without forest cover were most seriously affected by landslides.
A really interesting aspect of this event is the number of failures that originate from the ridge line – this is commonly the case for earthquake initiated failures, but not for those triggered by rainfall. But Toan et al. (2025) note that this area has water traps on the ridgelines to feed water for rice field irrigation, so it is likely that these increased the rate of saturation, triggering failure.
In some locations, multiple shallow landslides combined to generate channelised debris flows. Parts of Ho Bon commune itself were damaged by such an event.
In total, Toan et al. (2025) document 88 damaged or destroyed houses, and extensive damage to the main road (NH32) through the area. They do not document any fatalities.
References
Planet Team 2025. Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/
Toan, D.T., Duc, D.M., Quynh, D.T. et al. 2025. Extreme-rainfall-induced series of landslides and large flow-like landslides in Ho Bon commune, Mu Cang Chai district, Yen Bai province, Vietnam, in August 2023. Landslides. https://doi.org/10.1007/s10346-025-02544-5
Text © 2023. The authors. CC BY-NC-ND 3.0
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