The California Geological Survey (CGS) has developed the Landslide Inventory Map Series to provide additional information to geotechnical professionals, local government personnel, as well as property owners and developers who use Seismic Hazard Zone Maps. Earthquake-induced landslide zones of required investigation include inventories of known landslides, but previously these inventories were only available as small-scale plates in seismic hazard zone reports.

Landslide inventory maps show locations and characteristics of landslides that have moved in the past but generally do not indicate the mechanism(s) that triggered them. The geologic, terrain and climatic conditions that led to past slope failures often provide clues to the locations and conditions of future slope failures. Therefore, inventory maps provide useful information about the potential for future landsliding. In addition, recognizing the type and recency of landsliding can also facilitate the scope and design of site-specific geotechnical investigations and guide slope remediation strategies.

Inventory maps are prepared primarily by geomorphic analysis of aerial photographs and secondarily by field reconnaissance, interpretation of topographic map contours and review of previous mapping. Landslides shown on the Landslide Inventory Map Series were compiled at a scale of 1:24,000 on the U.S. Geological Survey topographic map and several key characteristics are shown through cartographic symbology. Each map in this series contains an explanation of the map symbology as well as a brief description of the geology and landslide occurrences in the map area.

These landslide inventory maps are the first of many to be released in the San Francisco Bay and Southern California regions.  This series is a new addition to the list of publications that CGS currently distributes.  If you would like to purchase a printed Landslide Inventory Map you may do so by contacting CGS Publications.

How to download maps
To download a Landslide Inventory Map move your curser over a named quadrangle inside the colored region of the map and click on the quadrangle.  Alternatively, you can also download a map using an alphabetized list that is located at the end of the page.  All maps are in an Adobe Acrobat (PDF) file and you will need Adobe Acrobat Reader to view them.  Download Adobe Acrobat Reader.

(NOTE: The Landslide Inventory Maps have been integrated in to a statewide Landslide Map Index and can be accessed in CGS's Information Warehouse.)