Landslides and Engineering Geology of the Seattle, Washington, Area

Abstract

Seattle is a large city beset by the effects of ongoing urban development and redevelopment of a huge but fragile “pile-like” mantle of late Pleistocene glacial debris, exacerbated by considerable topographic relief, high rainfall, and a serious, yet incompletely understood, Holocene-aged regional seismotectonic regime. The editors—from the U.S. Geological Survey's (USGS's) remnant Denver cadre of engineering geologists—have delivered a timely update of Galster and Laprade's 1991 summary of Seattle's engineering geology. Six years after Galster and Laprade's summary, the Seattle area was subjected to record snowmelt and rainfall intensities, which caused damage sufficient to commission a long-term mitigation-based multi-hazards study by the USGS, in cooperation with the City of Seattle. This volume— Reviews in Engineering Geology XX —is just one publication from that effort. The text benefits from contributions by local practitioners who also had been dealing with various compelling elements of the overall threat. Taken together, all of the papers constitute a celebration of sorts, a “coming out” party for the new geologic map. For the first time, Seattle now has a geologic map rooted in the traditional mapping style of engineering geologists and serving the needs of the community. The Editors' Preface is followed by these articles: 1. Geology of Seattle and the Seattle Area, Washington ; by Kathy Goetz Troost and Derek B. Booth, 35 p. 2. Landslide mapping in Seattle, Washington ; by William T. Laprade and Donald W. Tubbs, 28 p. 3. Elevation errors in a LIDAR digital elevation model of West Seattle and their effects on slope-stability calculations ; by William C. Haneberg, 10 p. 4. Shallow landslide hazard map of Seattle, Washington ; by Edwin L. Harp, John A. Michael, and William T. Laprade, 15 p. 5. Assessing deep-seated landslide susceptibility using 3-D groundwater and slope-stability analyses, southwestern Seattle, Washington ; by Dianne L. Brien and Mark E. …