About Quaternary Faults > How Was the Map of Quaternary-Active Faults Made?

How Was the Map of Quaternary-Active Faults Made?

This map was produced as a collaborative effort of the USGS, California Geological Survey, and geologists in the academic and private sectors, using a variety of mapping techniques, including LIDAR, interpretation of aerial photographs, and on-the-ground mapping of faults.

The map was compiled from three sources.  The first was detailed new mapping of faults throughout the region.  These contributions are listed below:

• Compressional faults, northeastern San Francisco Bay region—J. Unruh, William Lettis & Associates
• Concord-Green Valley Faults—B. Bryant and C. Wills, CGS
• Faults in Santa Cruz and northern Monterey County—L. Rosenberg, Tierra Geosciences
• Foothills Thrust System, Santa Clara and San Mateo Counties—D. Kennedy, Sanders & Associates
• Hayward Fault—J.J. Lienkaemper, USGS
• Northern and Peninsula segments of the San Andreas Fault—C. Prentice, USGS
• Northern Calaveras Fault—K. Kelson, William Lettis & Associates
• Rodgers Creek Fault—S. Hecker, USGS, and C. Randolph-Loar, Lachel Felice & Associates
• West Napa Fault—K. Hanson, Geomatrix (www.geomatrix.com), and J. Wesling, William Lettis & Associates

The second source was the map of Quaternary-active faults of California, prepared by B. Bryant, CGS, for the National Quaternary Fault Map Database.

The third source was the geologic map of the San Francisco Bay region.