THE CALIFORNIA LANDSLIDE INVENTORY DATABASE

Landslide inventory maps are the most basic type of landslide hazard maps. They portray the location of past landslides, which are indicators of a region’s landslide susceptibility. Generally, landslide inventories represent a geomorphic interpretation of an area and identification of landforms that may have formed by landsliding. Inventory maps do not necessarily distinguish the age of landslide movement, but given a triggering event some of the mapped slides—or more frequently, portions of them—may become active. The California Geological Survey (CGS) is digitizing existing maps of landslides and has prepared a statewide landslide database that is now available online. The database shows many of the landslides mapped by CGS and others over the past 50 years. Individual landslide records reflect the standards of the project for which the landslide was mapped. Many maps show landslide source areas (scarps) separately from landslide deposits while others combine scarps and deposits into a single feature. The information recorded about each landslide has increased over time, so more information is available for more recently mapped landslides. Updates to the database are continuing, both to include more existing maps and to add or update current landslides as they occur. The landslide inventory, in combination with the map of susceptibility to deep-seated landslides (CGS Map Sheet 58) can give local planners, infrastructure owners, and the public a perspective on where landslides are most likely to be triggered by winter storms or by earthquakes in California.