1 September 2017
Stunning, unbelievable, high resolution footage of the Zhangjiawan rockslide
Reader Fabien has kindly pointed out to me that Liveleak has new footage of the Zhangjiawan rockslide in Guizhou Province in China, which killed 26 people and left a further nine missing and presumed killed. This is the recording, which sadly has no further metadata. Frustratingly WordPress no longer allows me to embed Liveleak videos, so I have embedded the Youtube copy of the video:-
This is undoubtedly one of the best ever recordings of the development of a major rockslide, capturing the precursory rockfall activity as well as the final failure event. The impression is clearly of a progressively disintegrating rockmass, rapidly fragmenting as movement develops. This may well be associated with the development of rotation in the mass. I have captured three elements of the initiation of the final collapse below:-
This sequence shows that at the point of the development of rapid motion the rockslide was undergoing both toppling (i.e. the mass was rotating such that the upper section of the rockmass was moving more rapidly than the lower portion, and the whole mass is in effect tilting forwards) and basal sliding into the valley. This is a large-scale version of the motion that can be imagined from this simple block diagram, although obviously it was far more complex when on the scale of the Zhangjiawan rockslide:-
Meanwhile, in a comment on my previous post my good friend Tim Davies asked about the runout of the landslide, and in particular spectulated that the runout length might have been quite short. This ChinaNews image shows the full landslide track:-
This suggests that whilst not being hyper-mobile, the track was probably not very short. There are some signs that the portion on the right side of the image has transitioned into a flow I think. Xinhua reports that the landslide volume was about 600,000 m³, with a fall height (I assume of the initial failure) of about 200 m.
I have not yet been able to locate this landslide reliably. Has anyone else had any luck?