Dave Petley, an expert in the field of landslides, is the author of The Landslide Blog and is highly regarded for his knowledge and skills in researching and handling landslides.
In the past, I have seldom shared information about landslides in South Africa. However, during the weekend of September 23-24, 2023, heavy rain from a storm caused numerous slope failures in the country. The largest amount of rainfall (299 mm) was recorded in Franschhoek, located at coordinates -33.897, 19.152.
As a consequence, numerous landslides were set off in Franschhoek, impacting both transportation routes and structures. Franschhoek life shared a series of aerial photographs of these landslides on Twitter, captured by Jean Tresfon and shared on Facebook.
One of the most fascinating sites with numerous landslides can also be seen in the Facebook images provided below.
The image above displays multiple debris flows that seem to have taken place at the coordinates [-33.880, 19.091]. The location can be seen on the Google Earth image below:
These appear to be excellent illustrations of minor, superficial landslides in eroded rock that have carried material downhill. In Hong Kong, they are known as open hillslope flows because they have not formed a defined channel. The distance of the debris flow is quite significant. It is evident that the incline has been cleared of trees in recent times. The landslides began above this location, but I am curious if the deforestation played a role in the distance the debris traveled. There is a substantial amount of material being carried along this section of the slope.
In other areas of Franschhoek, there were reports of landslides. According to a News 24 article, a well-known person had to leave a building due to a mudslide at the MontMartre estate. The article also contains pictures of the chalet’s destruction.
Text © 2023. The authors. CC BY-NC-ND 3.0
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