Fault Active within the Quaternary, California (2010)

The 2010 Fault Activity Map of California presents a much more detailed depiction of faults in California than previous versions. In order to preserve as much of the original detail as possible, most faults active in the Quaternary (2.6 Ma) were digitized from their original sources (geologic maps ranging from 1:12,000 to 1:250,000 scale). However, due to limitations associated with printing the map at the 1:750,000 scale, some of the fault traces have been simplified or omitted. For a complete, unsimplified database of Quaternary faults, refer to the Digital Database of Quaternary and Younger Faults from the Fault Activity Map of California, Version 2.0 (Bryant, 2005; http://www.conservation.ca.gov/cgs/information/publications/Pages/quaternaryfaults_ver2.aspx).

A significant difference from the 1994 version of the Fault Activity Map of California is the method of fault compilation. Almost all of the Quaternary faults shown in the 2010 version of the Fault Activity Map have been digitally compiled from original-scale source maps (1:12,000 to 1:250,000) used for the 1975 and 1994 maps, as well as more recent mapping when available. This compilation method insures that locations of these faults are more accurate than those depicted on previous editions of the Fault Activity Map. The Pre-Quaternary faults remain the same as in the 1994 version.

The geographic information system (GIS) files in this data package were created using ESRI ArcGIS. The *.gdb file is an ESRI File Geodatabase, version 10.1. The *.shp files are ESRI Shapefiles which were exported from the file geodatabase using ArcMap's "export" functionality. The *.dbf, *.prj, *.sbn and *.shx files support the *.shp files and contain necessary and important data that are referenced by the *.shp file. The *.mxd file is an ESRI Map Document file, which controls the display of data from the ESRI geodatabase, in this case using the same colors and symbols as the printed map. The Map Document file can be opened only with ESRI ArcGIS 10.1 or later. The ESRI Shapefiles can be opened with a wide variety of commercial and open-source GIS software, including Geomedia, GRASS GIS, MapInfo and Quantum GIS. The Shapefiles and Geodatabase contain the same geologic data.