Lessons from the Oso Landslide

Presented by Marvin R. Pyles, Ph.D., P.E., F. ASCE, professor emeritus of forest engineering, Oregon State University

Abstract: On March 22, 2014, in Washington State, a landslide of nearly 10 million cubic yards moved rapidly from the north side of the Stillaguamish river across the river, through the Steelhead Haven neighborhood, and across SR 530, demolishing all the homes in the neighborhood, engulfing automobiles on the highway, and killing 43 people – men, women, and children. Investigation of the landslide done under the authority of the Attorney General of Washington developed geotechnical data that suggests a convergence of factors as the likely cause of the landslide. This is not particularly surprising for a natural landslide. Perhaps more importantly, analysis of the landslide demonstrated the shortcomings of a number of geotechnical investigation and analysis methods, and pointed to the lack of a standard with respect to quantifying landslide hazard and risk. Further, the litigation that followed the landslide demonstrated a number of aspects of litigation that are incompatible with the author’s perspective about sound geotechnical professional practice.

Biography: Marvin Pyles is a professor emeritus of forest engineering at Oregon State. For 33 years, he taught geotechnical engineering in the forest engineering, civil engineering, and construction engineering management programs at Oregon State. Dr. Pyles is an Oregon State civil engineering alum, having received his BS and MS degrees from Oregon State. He received his PhD from the University of California, Berkeley. Over the course of his career he also taught at San Diego State University, and the University of Canterbury in New Zealand. He is a Registered Professional Engineer in California, Oregon, and Washington, and has maintained a consulting practice for the past 40 years.