There are those who can afford to live on the edge. In this case, the edge of a steep hillside, overlooking Puget Sound. Many of those also enjoy a large, flat lawn from which to enjoy the view. These two things are compatible, normally, only with some intensive engineering of structures to stabilize the hillside.
This very nice older lady was concerned that her property was in danger of sliding downhill – and in fact, that is possible. The nice, flat yard you see in the photo is created by building a retaining structure some way down from the edge of the steep hillside, and filling behind that retaining structure with soil.
Decades ago, no one really thought about the effects such construction has on the hillsides. As it happens, the extra weight of soil reduces the stability of the underlying native soil, sometimes leading to slides. Decades ago, this was not really a problem, because even when such slides occurred, they usually did not affect anyone. But as the population density increases, and people build closer to the edge, the number of slides increases.