A transnational, valley blocking landslide in Africa – GWC Mag

The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.

On 23 February 2024, a large valley-blocking landslide was triggered by heavy rainfall in the Ruzizi Valley, to the south of the city of Bukavu, which is in the Democratic Republic of the Congo (DRC). There are some images of the landslide online, the best is on the La Prunelle Verte website – take a look if you can. The Chronicles has also tweeted a short video of the landslide:-

VIDEO – There has been a major landslide on River Rusizi, the actual border between Rwanda & DR Congo. River links L. Kivu & Tanganyika. An entire hillside has blocked path of the river about 15km north of Bukavu town. Flooding expected upstream & down when river eventually flows pic.twitter.com/xLHwzcJwCj

— The Chronicles (@ChroniclesRW) February 24, 2024

And Africa News has posted a video to Youtube as well:-

This is a fascinating landslide as it has occurred on the border between Rwanda to the east and the DRC to the west. In fact, the landslide itself is on the Rwanda side of the border, on Nyiratengo hill. The impacts of the landslide are thus occurring in two countries simultaneously, which is an unusual situation

I’ve downloaded a Planet Labs image of the landslide, and have imported it into Google Earth:-

The location of the landslide is [-2.5603, 28.8956]. As the image above shows, it has blocked the valley, although flow has been restored. However, a substantial volume of water remains impounded, which is a threat to downstream communities. News reports indicate that houses have been flooded by the impounded water.

This site needs careful monitoring.

The landslide has occurred on the site of a pre-existing failure – this is a Google Earth image from March 2023:-

The two arcuate shallow failures at the top of the slope are clear, but my interpretation is that these are more recent failures in the back scarp of an older, larger landslide. The crown of the main landslide mass is in the midslope area. It is this mass that appears to have failed in the most recent event, although this in turn has debuttressed the upper slope, which has also failed.

The stability of the site is not clear, so there is a risk of further failures, which could block the valley again.

BNN has a nice overview article about the landslide, which includes the following:-

“As the region grapples with the aftermath of this calamity, there is a pressing need for a coordinated response to address both the immediate needs of the affected communities and the broader security concerns. Strengthening infrastructure, enforcing stricter controls at border crossings, and implementing comprehensive disaster management strategies are critical steps toward mitigating the impact of such events in the future. The interconnectedness of natural disasters across borders, as exemplified by this incident, underscores the importance of regional cooperation in disaster preparedness and response”

I agree.

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