This mudslide was actually predictable, I did a little research and there have been other slides at the same spot in the past.
Anyone who lived there had to know that they were living on borrowed time.
People who decide to live at dangerous locations put the lives of those who will have to rescue them or recover their bodies at risk.
I've bought 2 houses here in the greater Seattle area and I MADE SURE I wasnt on a cliff, under a cliff, on a beach (couldnt afford that anyway but didnt want it either), on or near a river or even in a floodplain. I also made sure I didnt buy a brick or mostly stone house as they do very poorly in earthquakes. Neither of my houses had huge trees directly over them. (And our trees are huge...in windstorms, branches bigger than trees in other places come down on your houses and cars).
I actually have some drop-dead views from my place...but just peek a boo from the house...you have to go out to the pasture for clear views of the mts....
The danger I will face in the future is wild fire or forest fire...because I do eventually want to move further out...that's going to be a tough call.
You can clearly see from the aerial views that there were historically and prehistorically the same types of slides. See the same (overgrown) cuts in the ridges and where the slides pushed the river off course.
But they are not predictable as you seem to imply.