I had wondered about an earthquake possibly being involved with causing this; and now it does appear that this might indeed have been at least a part of what happened here.
There is an earthquake fault line (Devil's Mountain fault line) that runs right along the area where the mudslide occurred, and this might have been responsible for the slides that have occurred near there. Apparently, there was also one about a year ago, just not a bad one.
Another reason that could have been a cause of the slide, is that there was apparently logging in the area, either recently, or in the past.
When they log in Western Washington, they do what is called "clear-cutting", which means that every single tree is taken down (making it easier for the loggers) which then leaves ugly bare hillsides like this with no trees and root systems to help hold the land in place. The slide started from the bottom of the mountain, which left nothing to support the top, so it came crashing down on top of the rest of everything, creating mud piles said to be up to 180' deep in some places. It is no wondr they can't get in there to find missing people !
Plus, the area where the slide came down was exactly where a little community of houses once was. If you look at the google map of the area, you can see the homes happily nestled in the curve of the river right at that point.
The map below shows the area where the slide happened, and you can see the red fault line on the right side of the picture, where it crosses the river, right at the same place as the landslide occurred.
I read that they are supposed to be sending in the National Guard to help tonite. I only wish they could have gotten more help there sooner, and saved more lives.
