What happened on the Nepal/Tibet border is awful. A glacier basically breaking off, speeding down a mountain, and just erasing everything down a river valley. Basically a million-ton iceberg acting like a roller-coaster car and a bunch of villages disappearing under it.
I had watched a video a few months about about a big damn breaking the moment it got to it's max fill point on the reservoir side in Idaho, maybe back in the 60s. It flooded a number of towns, but was relatively tame compared to the radical acceleration the steep valley caused in Nepal/Tibet.