Displays areas of landslide events based on a Seattle Landslide Study completed by Shannon and Wilson.A polygon feature class showing 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.Updated as needed.