Flash flood

The tragic and terrifying Himalayan flash flood was caused by a chunk of mountain collapsing into a narrow gorge, sending a tsunami of mud and rock that gathered mass as it shot down the steep Trisuli river valley. More than that is not yet clear. Did a breakaway hanging glacier take a rock face with it or was it the other way round? Was there time for the debris to dam the valley and form a lake that burst or did the 60-metre flood of mud come from ice, river water, rock and soil that accumulated in the valley as the tsunami descended? Some people are already certain they know what caused this. Either climate change did it or China did it. Assorted greens rushed to blame global warming with confidence bordering on certainty.