The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
Back in February I highlighted a Sixth Tone article about the extraordinary landslide cluster that was triggered by Typhoon Gaemi in Hunan Province in China between 26 and 28 July 2024. A paper (Zhao et al. 2025) has now been published in the journal Landslides that provides a more detailed documentation of the event.
As a reminder, this is a Planet satellite image of the aftermath of Typhoon Gaemi in Zixing County, the worst affected area:-
Zhao et al. (2025) have recorded 19,764 landslides from this single event, an extraordinary number. It is worth looking in a little more detail at the density of landslides in this area. The marker in the centre of this image is located at [23.13507, 95.78573]:-
Zhao et al. (2025) note that 128,000 people were affected, with 1,714 houses being destroyed and 65 people killed.
A key issue in an event such as this is the rainfall conditions that can cause such an impact. During Typhoon Gaemi, Zixing County averaged 412.7 mm of rainfall, but one weather station recorded 673.9 mm. The maximum 24 hour rainfall was 642.5 mm; the previous record 24 hour rainfall in Hunan Province was 365.4 mm. Thus, this event broke the record to an extraordinary degree. In a landscape with many slopes, multiple landslides were inevitable. I would however be very interested in the peak hourly rainfall, which is likely to have been a key factor, if this data is available.
The failures were mostly small, shallow landslides. The landslide rate was higher in areas in which there had been excavation of the slope for roads or houses.
These types of intense landslide clusters are not in any way unprecedented, but the number of events globally in 2024 was unusually high. This is driven by extreme rainfall associated with the exceptionally high atmospheric temperatures last year.
It is a sign of what is to come in the years ahead.
Reference
Zhao, J., Feng, W., Yi, X. et al. 2025. Clustered shallow landslides caused by extreme typhoon rainstorms in Zixing County, Hunan Province, China, from July 26 to 28, 2024. Landslides. https://doi.org/10.1007/s10346-025-02508-9
Planet Team. 2025. Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/