NH-11:
The 22 March 2014 Oso, Washington Landslide
Tuesday, 17 June 2014
146B-C (Washington Convention Center)
Joseph Wartman1, Jeffrey R Keaton2, Anderson Scott3, Jean Benoit4, John delaChapelle5, Robert Gilbert6, David R Montgomery1 and Geotechnical Extreme Events Reconnaissance (GEER) Oso Landslide Investigation Team, (1)University of Washington, Seattle, WA, United States, (2)AMEC, Los Angeles, CA, United States, (3)Federal Highway Administration, Denver, United States, (4)University of New Hampshire Main Campus, Durham, NH, United States, (5)Golder Associates, Inc., Redmond, WA, United States, (6)University of Texas at Austin, Austin, TX, United States
Abstract:
The Oso (Snohomish County), Washington Landslide is among the most significant geologic disasters in recent U. S. history. The landslide occurred on a valley slope with a history of intermittent landslide occurrence dating back to the 1940s, with previous landslide movement in 2006 that blocked the river but did not affect any homes. The Oso Landslide is one of many landslides that have occurred on slopes in the valley of the North Fork of the Stillaguamish River. The 22 March 2014 Oso Landslide became a rapidly moving, unchannelized debris flow that spread out as it travelled about 1 km, damming the North Fork of the Stillaguamish River, destroying and carrying away about 50 homes, and burying about 1.5 km of State Highway 530. There are 45 confirmed deaths or missing persons. Developing and advancing strategies for adapting to climate-triggered earth surface processes requires that we understand what happened leading to the collapse of the slope so that communities and infrastructure systems can be designed for greater resiliency and enhanced public safety. We will report the findings of our National Science Foundation-supported Geotechnical Extreme Events Reconnaissance (www.geerassociation.org) investigation of the landslide, highlighting its impacts as well as important policy and risk communication aspects of the event.
