31 March 2016
Pakistan: a highly destructive landslide caught on video
A new video has appeared on Youtube and Liveleak showing a landslide in Pakistan. The slide appears to have started high up on the slope, but unfortunately the video quality is not good enough to ascertain properly what is happening. It appears to accelerate rapidly down the lower slopes – but see below because the mechanism is more complex than it appears – and then crashes through a series of houses:-
Taking a look at the video in a little more detail, clearly before the landslide appears on the lower slopes something is going on in the plateau area beyond the view of the camera. The people around the camera were aware of this, and appear to be trying to warn those on the slopes below of the danger. There is a lot of dust in the air at the top of the slope:-
It looks to me like the slope above the plateau is failing and moving, but it is hard to tell. Could this be a quarry?. About 27 seconds into the video, material starts to travel over the break of slope that marks the edge of the plateau, and it travels down the main slope. Compare the image below with the one above:-
But what happens next is the most interesting element. The debris flowing down the lower slope triggers another failure, probably in the deep soil and weathered rock that forms this area. This is just happening in the still below:
It is this secondary failure that destroys the houses, leaving the deep landslide scar behind:-
Technically this is a combination of an induced failure and a rapid entrainment event. It illustrates beautifully the complexity of landslides, and why it is so hard to forecast their behaviour.
Sadly there is no further information about this landslide – does anyone know any more?