Hydrologic Monitoring of Landslide-Prone Coastal Bluffs near Edmonds and Everett, Washington, 2001-2004 Open file rept

摘要

Landslides on coastal bluffs between Seattle and Everett, Washington, have posed a major safety hazard to transportation since the 1800s. Large numbers of landslides in 1996 and 1997 resulted in damage to property and temporary disruption of railroad service; the January 15, 1997, Woodway landslide derailed several cars of a freight train (W.A. Hultman and D.N. McCulloch, Shannon and Wilson, Inc., written commun., 1997; Baum and others, 1998). With the exception of the Woodway landslide, the vast majority of these landslides were shallow. In 2001, a cooperative monitoring effort between the U.S. Geological Survey (USGS), the Burlington Northern Santa Fe Railway (BNSF), BNSFs geotechnical consultant, Shannon and Wilson, Inc., and the Washington Department of Transportation was begun to determine whether near-real-time monitoring of rainfall and shallow subsurface hydrologic conditions could be used to anticipate landslide activity on the bluffs. Monitoring currently occurs at two sitesone near Edmonds, Washington, and the other near Everett, Washington. During initial planning, the USGS proposed to evaluate the monitoring results at the end of 3 years. This report summarizes site conditions, methods, system reliability, data, and scientific results, and identifies possible future directions for development of monitoring and early warning of impending landslide activity.