Formula for a Landslide

The landslide tragedy in Oso, Washington, occurred in a region of North America that is especially prone to such events.  Landslides generally occur in areas where porous, poorly-compacted sediments, lying on steep slopes, are subjected to a period of heavy precipitation.

Across the Pacific Northwest,  Late Tertiary and Pleistocene volcanic debris and glacial till are spread across older ranges of the Cascades and, as most of us know, that region is subject to episodes of copious rain and snow, courtesy of the Pineapple Express and other Pacific storm systems.  In most other parts of our Continent, loose volcanic and glacial sediments were deposited across relatively flat terrain or are not in the path of moisture laden storm systems; exceptions might include mountainous sections of the Northeast and hilly terrain near the Great Lakes.

While we cannot change the geology or topography of our regional landscapes, we can choose to avoid constructing homes and industrial plants in areas prone to natural catastrophe (floodplains and barrier islands come immediately to mind).  Yet, almost every region of our planet is subject to some form of disaster, from wildfire to flood or from earthquakes to hurricanes.  In the end, we choose to live in areas that appeal to us and accept the risk that comes with that choice.