A new paper in the journal Landslides has presented a review of a large landslide that killed 29 people in Sichuan Province.
On 8 February 2025, a large rock avalanche occurred in Junlian County in Sichuan Province, China. I wrote about this event, now known as the Junlian rock avalanche, at the time. With remarkable and commendable pace, Bo Zhao and colleagues have published an initial review of the event (Zhao et al. 2025) in the journal Landslides. Whilst the paper is behind a paywall, this link should allow readers to access the full text.
The landslide is located at [27.99885, 104.60801]. The Google Earth image below shows the site in 2020 – the marker is on the source area of the Junlian rock avalanche:-
The image below, published by Xinhua, shows the aftermath of the landslide:-
Zhao et al. (2025) have determined the key statistics for this landslide. The initial failure was 370,000 m3, increasing to 600,000 m3 through entrainment. The landslide had a runout distance of 1,180 metres and a vertical elevation change of 440 m, giving a landslide mobility index of 0.37. This is a typical value for a rock avalanche of this volume.
Zhao et al. (2025) show that the initial failure was structurally controlled, which is no surprise. It occurred in a Triassic interbedded sandstone and mudstone formation. They estimate that the average velocity was 19.3 m/second.
The authors consider in some detail the triggering event. The site experienced 10 days of low intensity rainfall prior to the failure. Zhao et al. (2025) suggest that this led to the build up of pore water pressure, initiating the failure. Total rainfall in the month proceeding the collapse was in the order of 85 mm. This rainfall seems somewhat unexceptional, suggesting to me that a progressive failure mechanism was in play.
The Junlian rock avalanche killed 29 people and left two people injured. It is a fascinating example of a major failure with high consequences in a remote mountainous area. Anticipating such events remains a major challenge in landsldie research. Many thanks to the authors for providing such a rapid description of this event.
Reference
Zhao, B., Zhang, Q., Wang, L. et al. 2025. Preliminary analysis of failure characteristics of the 2025 Junlian rock avalanche, China. Landslides. https://doi.org/10.1007/s10346-025-02556-1.