Regional landslide-hazard assessment for Seattle, Washington, USA

Landslides are a widespread, frequent, and costly hazard in Seattle and the Puget Sound area of Washington State, USA. Shallow earth slides triggered by heavy rainfall are the most common type of landslide in the area; many transform into debris flows and cause significant property damage or disrupt transportation. Large rotational and translational slides, though less common, also cause serious property damage. The hundreds of landslides that occurred during the winters of 1995–96 and 1996–97 stimulated renewed interest by Puget Sound communities in identifying landslide-prone areas and taking actions to reduce future landslide losses. Informal partnerships between the U.S. Geological Survey (USGS), the City of Seattle, and private consultants are focusing on the problem of identifying and mapping areas of landslide hazard as well as characterizing temporal aspects of the hazard. We have developed GIS-based methods to map the probability of landslide occurrence as well as empirical rainfall thresholds and physically based methods to forecast times of landslide occurrence. Our methods for mapping landslide hazard zones began with field studies and physically based models to assess relative slope stability, including the effects of material properties, seasonal groundwater levels, and rainfall infiltration. We have analyzed the correlation between historic landslide occurrence and relative slope stability to map the degree of landslide hazard. The City of Seattle is using results of the USGS studies in storm preparedness planning for emergency access and response, planning for development or redevelopment of hillsides, and municipal facility planning and prioritization. Methods we have developed could be applied elsewhere to suit local needs and available data.

[1]  William H. Schulz,et al.  Landslides mapped using LIDAR imagery, Seattle, Washington , 2004 .

[2]  Robert E. Kayen,et al.  Landslides and liquefaction triggered by the M 7.9 denali fault earthquake of 3 November 2002 , 2003 .

[3]  R. Soeters,et al.  Slope instability recognition, analysis, and zonation , 1996 .

[4]  W. Z. Savage,et al.  TRIGRS - A Fortran Program for Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Analysis, Version 2.0 , 2002 .

[5]  Richard M. Iverson,et al.  Landslide triggering by rain infiltration , 2000 .

[6]  N. Caine,et al.  The Rainfall Intensity - Duration Control of Shallow Landslides and Debris Flows , 1980 .

[7]  C. Westen,et al.  An approach towards deterministic landslide hazard analysis in GIS. A case study from Manizales (Colombia) , 1996 .

[8]  Mark S. Wigmosta,et al.  Land use and watersheds : human influence on hydrology and geomorphology in urban and forest areas , 2001 .

[9]  E. Harp,et al.  Landslides and Landslide Hazards in Washington State Due to February 5-9, 1996 Storm , 1969 .

[10]  R. D. Miller.  Map showing relative slope stability in part of west-central King County, Washington , 1973 .

[11]  Chen Chen-lung,et al.  DEBRIS-FLOW HAZARDS MITIGATION: MECHANICS, PREDICTION, AND ASSESSMENT , 2007 .

[12]  A. F. Chleborad,et al.  Preliminary evaluation of a precipitation threshold for anticipating the occurrence of landslides in the Seattle, Washington, area , 2003 .

[13]  Nicola Casagli,et al.  Rainfall patterns and related landslide incidence in the Porretta-Vergato region, Italy , 2004 .

[14]  Lorenzo Marchi,et al.  Assessment of shallow landsliding by using a physically based model of hillslope stability , 2002 .

[15]  Robert A. Crovelli,et al.  Probabilistic Assessment of Precipitation-Triggered Landslides Using Historical Records of Landslide Occurrence, Seattle, Washington , 2004 .

[16]  R. Baum.  Map showing recent and historic landslide activity on coastal bluffs of Puget Sound between Shilshole Bay and Everett, Washington , 2000 .

[17]  L. Highland,et al.  An Account of Preliminary Landslide Damage and Losses Resulting from the February 28, 2001, Nisqually, Washington, Earthquake , 2003 .

[18]  R. H. Campbell.  Isopleth map of landslide deposits, Point Dume quadrangle, Los Angeles County, California; an experiment in generalizing and quantifying areal distribution of landslides , 1973 .

[19]  Sarah B. Christian,et al.  Gravitational stability of three-dimensional stratovolcano edifices , 2000 .

[20]  E. E. Brabb.  Innovative approaches to landslide hazard and risk mapping , 1985 .

[21]  Rex L. Baum,et al.  Modeling regional initiation of rainfall-induced shallow landslides in the eastern Umbria Region of central Italy , 2006 .

[22]  Rex L. Baum,et al.  Rainfall characteristics for shallow landsliding in Seattle, Washington, USA , 2006 .

[23]  A. F. Chleborad,et al.  Preliminary method for anticipating the occurrence of precipitation-induced landslides in Seattle, Washington , 2000 .

[24]  Rex L. Baum,et al.  A model for spatially and temporally distributed shallow landslide initiation by rainfall infiltration , 2003 .

[25]  E. E. Brabb,et al.  Landslide susceptibility in San Mateo County, California , 1972 .

[26]  A. K. Turner,et al.  Landslides : investigation and mitigation , 1996 .

[27]  John A. Michael,et al.  Hazard analysis of landslides triggered by Typhoon Chata'an on July 2, 2002, in Chuuk State, Federated States of Micronesia , 2021, Open-File Report.

[28]  H. H. Waldron,et al.  Stratigraphy and chronology of late interglacial and early Vashon glacial time in the Seattle area, Washington , 1965 .

[29]  Lowland.  High-Resolution Lidar Topography of the Puget Lowland, Washington , 2003 .

[30]  Randall W. Jibson,et al.  A Method for Producing Digital Probabilistic Seismic Landslide Hazard Maps: An Example from the Los Angeles, California, Area , 1998 .

[31]  William A. Bryant,et al.  Probabilistic seismic hazard assessment for the state of California , 1996 .

[32]  David J. Harding,et al.  High-resolution lidar topography of the Puget Lowland, Washington - A bonanza for earth science , 2003 .

[33]  G. Wieczorek,et al.  Effect of rainfall intensity and duration on debris flows in central Santa Cruz Mountains, California , 1987 .

[34]  Jordi Corominas,et al.  Integrated Landslide Susceptibility Analysis and Hazard Assessment in the Principality of Andorra , 2003 .

[35]  Jonathan P. McKenna,et al.  Hydrologic monitoring of landslide-prone coastal bluffs near Edmonds and Everett, Washington, 2001-2004 , 2005 .

[36]  C. Chung,et al.  Probabilistic prediction models for landslide hazard mapping , 1999 .

[37]  Calvin F. Schmid,et al.  Basic Problems, Techniques, and Theory of Isopleth Mapping* , 1955 .

[38]  Marco Borga,et al.  Analysis of topographic and climatic control on rainfall-triggered shallow landsliding using a quasi-dynamic wetness index , 2002 .

[39]  Victor R. Baker,et al.  Surficial geology : building with the Earth , 1981 .

[40]  D. Varnes.  SLOPE MOVEMENT TYPES AND PROCESSES , 1978 .

[41]  David M. Cruden,et al.  LANDSLIDE TYPES AND PROCESSES , 1958 .

[42]  Robert A. Crovelli,et al.  Preliminary map showing landslide densities, mean recurrence intervals, and exceedance probabilities as determined from historic records, Seattle, Washington , 2000 .

[43]  Denys Brunsden,et al.  The nature, use and problems of historical archives for the temporal occurrence of landslides, with specific reference to the south coast of Britain, Ventnor, Isle of Wight , 1996 .

[44]  E. Harp,et al.  A method for producing digital probabilistic seismic landslide hazard maps , 2000 .