The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
Following my post last week about the 10 September 2024 Lang Nu landslide in Vietnam, the first author of the paper, Pham Tien of the Institute of Geological Sciences, Vietnam Academy of Science and Technology, has highlighted another really interesting failure. This is the 13 September 2024 Ba Thau landslide, which occurred in Xuan Thuong commune, Bao Yen district, in Lao Cai province of Vietnam. This landslide was also triggered by Typhoon Yagi.
The location of this landslide is [22.23164, 104.52894]. This is a Planet image of the site, captured before Typhoon Yagi on 6 September 2024. I have draped the image over the Google Earth DEM:-
Image copyright Planet, used with permission. Image dated 6 September 2024, before the failure.
Whist this is the same site on 3 October 2024, after the typhoon
Image copyright Planet, used with permission. Image dated 3 October 2024, after the failure.
As the image shows. this is a reasonably deep-seated translational rockslide that transitioned into a channelised flow. Fortunately, the runout was limited to about 800 metres, meaning that there were no fatalities. However, the Ba Thau landslide did destroy a large water tank that supplied clean water to several villages and schools.
Here is an image compare:-
Note that the satellite image also shows a number of other fresh landslides in the same area, albeit on a smaller scale.
Pham Tien has kindly provided this drone image of the head scarp of the landslide:-
The red dashed line highlights a tension crack, indicating a further failure could occur. This is similar in many ways to the situation that led to the dreadful 2024 Wayanad landslide in India.
This is a site that is going to need close monitoring in the future.
