For comparison, this is between 4 and 5 times larger than the Osceola Mudflow (<a href="https://en.wikipedia.org/wiki/Osceola_Mudflow" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Osceola_Mudflow</a>) that formed the 550km² of fertile plains around the south end of Puget Sound (near Seattle) and knocked a huge chunk out of Mount Rainier. If you drive from Auburn to Enumclaw, for example, notice how flat the land is and think about how that was hilly Cascade foothills and glaciated drumlins until 5500 years ago. The Osceola event was way bigger than Mt St Helens, and this one in the Himalayas was way bigger even that that.<p>Back-of-envelope, that Osceola event released about 10^19 Joules of energy*. The scale of these things is absolutely incredible.<p>According to my father, until around the time he was doing Geology at university (late 1960s), the consensus was that these kinds of events (and mass wasting more generally) were geologic processes that no longer happened (and hadn't really happened throughout the Holocene). I don't know the history in detail there, but it does seem true that only relatively recently we've had a real appreciation for how active Earth's geology still is.<p>* 4e15 cubic centimeters of material, 2 g per cc mix of rock and ice, mean elevation change 1000m