Geologic map of the Hayward fault zone, Contra Costa, Alameda, and Santa Clara Counties, California: A digital database

This digital map database, compiled from previously open- filed U.S.
Geological Survey reports (Graymer and others, 1994, Graymer,
Jones, and Brabb, 1994) and unpublished data, represents the
general distribution of rocks and faults in the Hayward fault zone.
As described in this report, the Hayward fault zone is a zone of
highly deformed rocks which trends north 30 degrees west from an
area southeast of San Jose to the San Pablo Bay, and ranges in
width from 2 to 10 kilometers. Although historic earthquake
activity has been concentrated in the western part of the zone, the
zone as a whole reflects oblique right-lateral and compressive
deformation along a significant upper crustal break over the past
10 million years or more. Together with the accompanying text file
(hfgeo.txt), the database provides current information on the
distribution and description of faults and rock types within the
fault zone. In addition, the text file discusses the development
of the fault zone in the past 10 million years, the relationship of
the Hayward and Calaveras fault zones, and the significance of the
creeping strand of the Hayward fault (as most recently defined by
Lienkaemper, 1992).