Blowout landslides, part 2: Material movement, and did anything actually “blow out?”

I have not personally witnessed one, but I think that a look at details of failure surface shape and the behavior of saturated soil during failure can be used to figure out why blowouts appear to “blow out” instead of just slide. In a second rare move for this page, I again link to an original post on the Appalachian Landslide Consultants site, which presents a host of sketches, a GIF of the model above, and a link to YouTube video of the actual New Zealand slide screenshotted below, which offers insight into the details of blowout material movement. The scar left by this blowout also provides a look at the flat area that creates a lip at the base of blowout failure scars.