I was doing a little google-fu after seeing a local map of the area and saw something quite disturbing. Admittedly, I googled what appeared to be the address where the mudslide happened based on a news report and I can't get confirmation the address is accurate. My original intent was to see the neighborhood density of the area using a satellite view on google maps, however, while looking at the satellite view I noticed what appears to be a scarp indicating previous movement of this same section of land that slid. If so, with just a little basic geology knowledge, this whole thing could have been foreseen well in advance (like decades in advance).

Note the roughly north/south scarp along the left side of the photo (you can google east Steelhead Drive, Arlington, WA to see the actual image you can zoom into). That's a classic warning sign I learned about in my Geology 101 class in college 20+ years ago.
From National Geographic
I have no intent to point fingers here, just noting that this might have been a tragedy that could have been foreseen well in advance if the right person in the right position had stepped up and said something.
Also, back to my original mission, it looks like there's about 25-30 or so homes that were in what appears to be the impact area. That obviously jives with the current missing count of 108. This whole thing is just beyond tragic.