Oso Washington Landslide Risk Goes Back Decades

In March, 2014, 40 people perished in a landslide in Oso, Washington.  Based on research from the University of Washington, many landslides in the same place may have occurred many times in the past.

Since the 1950s, geological reports on the hill that buckled have pessimistic analyses and the occasional dire prediction.  But no language seems more prescient than what appears in a 1999 filed with the U.S. Army Corps of Engineers, warning of "the potential for a large catastrophic failure".   The hill that collapsed in referred to by geologists with different names, including Hazel Landslide and Steelhead Haven Landslide, a reference to the hillside's constant movement.

According to Howard Coombs, "It is almost impossible from a practical standpoint to stabilize the slide in its present position.  The slope will continue to slide and the area will increase."  Coombs concludes the statement by adding that any earth retaining structures within the slide would give at best a temporary relief.  The structures would need constant repair and replacement."