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Open-File Report O-16-02, Landslide susceptibility overview map of Oregon, by William J. Burns, Katherine A. Mickelson, and Ian P. Madin.
Look up landslide susceptibility information for your neighborhood
with DOGAMI interactive maps HazVu and SLIDO.
1. Use the “enter address” field at the top of the map to enter your location:
2. Select the “landslide hazard” box in the Map Contents layers.
Open-File Report publication includes:
GIS data consist of one georeferenced raster file in .tif format. The data in this raster depict statewide landslide susceptibility at 10-m2 (32.8 ft2) resolution. We created the data by using Oregon Lidar Consortium (OLC) data and USGS NED data where OLC data were not present. We then converted elevation data into slopes and used a multi-pronged analysis process on the slopes, geology, and mapped existing landslides to create the 10-m2 raster. There are four classes of landslide susceptibility: Low, Moderate, High, and Very High. These data correspond to the zones shown on Plate 1.
Geographic Coordinate System: GCS_North_American_1983_HARN
O-16-02_report.pdf - 48-page text report in PDF format.
Summary from the report:
This project provides a generalized (1:500,000 data scale; ~32 square ft grid) landslide susceptibility overview map of the entire state. The intended use of this overview map is to help identify regions (cities, counties, communities, portions of lifelines, watersheds, etc.) that may be at risk for future landslides. The map is designed to provide landslide hazard information for regional planning and specifically to identify areas where more detailed landslide mapping is needed.
The landslide susceptibility overview map of Oregon uses three statewide data sets: 1) geologic map (a pre-release version of the Oregon Geologic Data Compilation, release 6), 2) landslide inventory (Statewide Landslide Information Layer for Oregon [SLIDO], release 3.2), and 3) slope map (lidar-derived data and U.S. Geological Survey national elevation data). We combined generalized geology and landslide inventory to determine landslide area per geologic unit area and to establish classes of low, moderate, and high landslide density. Then we calculated spatial statistics of the slope map to determine classes of low, moderate, and high slopes prone to landsliding within each geologic unit. Using a hazard matrix, we combined these two data sets, landslide density and slopes prone to landsliding, with the original landslide inventory to establish final landslide susceptibility overview map zones.
The statewide overview map zones classify Oregon into the following susceptibility zones: 37% low, 28% moderate, 30% high, and 5% very high (the very high zone by definition consists of mapped landslides). Most areas classified as moderate or higher landslide susceptibility are located in the Cascade Mountains, the Coast Range, and the Klamath Mountains and portions of central and northeastern Oregon.
We used the SLIDO-3.2 historic landslide point data set (9,997 points) to test the landslide susceptibility overview map. We found approximately 80% of the landslide points in the high and very high classes. We examined correspondence between landslide susceptibility and the 242 cities, 36 counties, and 536 watersheds (average watershed size of 170 mi2) in Oregon (Appendix C). In the counties, high and very high susceptibility percentages range from less than 10% in Deschutes County to greater than 80% in Tillamook County. Note, however, that a high percentage of landslide susceptibility for county, city, or watershed does not mean there is an equivalent high risk, because risk is the intersection of hazard and assets. For example, Tillamook County has greater than 80% high and very high landslide susceptibility, but if the majority of assets (people, buildings, infrastructure, etc.) are located in the other 20%, which is ranked moderate to low susceptibility, this indicates a relatively high overall susceptibility for the county, but a relative low risk for the county.
Files in PDF format are duplicates of the appendices in the text report. Files in Microsoft Excel format (.xlsx) are spreadsheets of the same data as shown in the appendices of the text report.
O-16-02_plate1.pdf - map plate in PDF format. Scale 1:750,000, 55 x 35 inches.
Plate 1. Landslide susceptibility overview map of Oregon, scale 1:750,000: