Dr. Scott Anderson: Geotechnical Engineering Technical Service Team manager (retired) for the Federal Highway Administration (FHMA) |

Title: Technical Observations from the 2014 Oso (SR 530) Landslide Reconnaissance

Abstract: The Oso Landslide struck the community of Oso, Washington on Saturday, 22 March 2014, at approximately 10:37 a.m. on a clear, sunny day. It initiated within an approximately 200-m-high (650 ft) slope comprised of unconsolidated glacial and colluvial deposits and then transitioned to a catastrophic debris flow and rapidly inundated a neighborhood and, traveling more than a kilometer (0.6 mi), crossed a state highway (SR 530). Forty-three people in the neighborhood and on the SR 530 highway lost their lives. There are lessons of all types to be learned from this disaster and these lessons will be explored – with special emphasis on the technical ones, and the consideration of risk and resilience.