29 August 2017
Zhangjiawan landslide: a massive rockslope collapse with 35 fatalities caught on a remarkable video
Whilst so much attention is focused on a very different, very serious disaster in Houston, another major landslide accident has occurred in China, this time in Zhangjiawan in Ghuizhou Province. Xinhua reports three known fatalities and 32 people missing; the likelihood of any further survivors is vanishingly small. The landslide occurred at 10:40 am yesterday (28th August) at Zhangjiawan Township, Nayong County. The slide buried 34 houses; seven people were recovered alive but injured.
Xinhua has two very impressive images of the landslide. This one provides a panoramic overview of the site:-
Whilst this one provides more detail of both the landslide source area and the deposit:-
Perhaps most amazingly, this landslide was captured on a video that has been uploaded onto Youtube by CCTV:-
This appears to be a massive rockslide, with a fair amount of toppling as the landslide developed. Unusually for a non-seismic slide the failure seems to have developed from the ridge crest and then to have entrained debris from lower on the slope. The result is a landslide with a morphology that is more reminiscent of an earthquake-induced slide. It is notable that there is a high proportion of highly weathered material in the landslide, especially in the scar, much of which seems to have fallen from the upper part of the slope (the deposit itself is mostly intact rock blocks with a mantle of weathered material). This suggests perhaps that there was a highly weathered zone high on the slope that provided the structural weakness for the failure.
The trigger for the landslide is not clear, but this is of course the rainy season in China