It appears that the side of a 6000m (20000 ft) mountain collapsed. Clearly this has happened many times through the geological history of the Himalaya - which

It appears that the side of a 6000m (20000 ft) mountain collapsed. Clearly this has happened many times through the geological history of the Himalaya - which is arguably the most extreme and dynamic mountain range on the planet - but on human timescales this is an extreme outlier event, so very hard to plan for.