Overview:
Overnight in early December, a series of landslides triggered by heavy rainfall hit two villages in Tanzania, killing at least 85 people.
The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
On 2 – 3 December 2023, very heavy rainfall struck the Northern Manyara region in Tanzania in Africa, triggering damaging landslides. Worst affected appears to be the area of Mount Hanang, a dormant volcano that extends to an elevation of 3,420 metres.
The most serious impact was on the towns of Katesh and Gendabi in Hanang district. The final loss of life is not yet clear, but at least 85 people were killed. A further 139 people were injured.
There are some videos of the landslides, most notably the one below, which shows the debris passing through Katesh:-
The President’s official Twitter account also posted these images of the landslides, which are clearly channelised debris flows:-
This is a very cloudy area, but Planet Labs has managed to capture some imagery of the landslides using their PlanetScope instruments. In the catchment above Katesh we see multiple shallow landslides that have transitioned into channelised debris flows:-
The location of this area is [4.45193, 35.41731].
Downstream, the landslide has impacted Katesh directly:-
News reports indicate that about 100 houses were destroyed. The location is [4.51201, 35.40233].
Meanwhile, Gendabi is located to the west of the mountain. There is currently no good imagery of the source area of these landslides, but the typology and impact downstream looks to be very similar to that of Katesh, suggesting that this was also a channelised debris flow:-
The location of this event is about [4.42429, 34.35194].
There is speculation that the rainfall that triggered these landslides might be associated with the current El Nino event, but further work is needed to confirm this.
Acknowledgement
Planet Team (2023). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/