City of Seattle ArcGIS OnlineThis group layer includes point, line, and polygon symbology to display the landslide event inventory. Used to implement and regulate the City of Seattle's Environmentally Critical Areas (ECA) policies. This layer includes a more comprehensive collection of slide events maintained by Shannon and Wilson via the Seattle Landslide Study which included slide data through June 1999. The Known Slide layer was most recently updated under SDCI Director's Rule 12-2019 . For more information about the definition of known slide areas, see Seattle Municipal Code section 25.09.012 , Environmentally Critical Areas (ECA) definitions. Updates as needed. ECA - Known Slide (Affected Property) : A polygon feature class showing landslide event inventory. ECA - Known Slide (Initiation Point) : A point feature class showing landslide event inventory. ECA - Known Slide (Scarp) : A line feature class showing landslide event inventory.ArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/f353794bcd1e4ddfa04097c9052e07df_2engSeattle GeoDataPublicECA - Known Slide (Initiation Point) [Washington (State)--Seattle]Web servicesWashington (State)--SeattleWashington (State)Last Modified: 2026-02-17