San Andreas fault trace, old and new

Simple illustration of a map of a bay and lines to show where tectonic faults are located offshore of the bay.

Detailed Description

High-resolution aeromagnetic data illuminates the geometry of the San Andreas fault offshore of the Golden Gate. Interpretation of the data by Jachens and Zoback (1998) and Zoback et al. (1999) indicated that the San Andreas fault makes a 3 km right step north of Lake Merced and a smaller 1 km left step south of Bolinas Lagoon, as shown by the red line. The orange line shows the trace of the San Andreas if it were a continuous tectonic feature, which is an older interpretation.


Image Dimensions: 351 x 421

Location Taken: San Francisco, CA, US


Eric Geist, USGS
For more info, see:

Jachens, R. C.,  and Zoback, M. L. (1999) The San Andreas Fault in the San Francisco Bay Region, California: Structure and Kinematics of a Young Plate Boundary, International Geology Review, 41:3, 191-205, doi: 10.1080/00206819909465139

Zoback, M. L.,  Jachens, R. C., and  Olson, J. A. ( 1999) Abrupt along‐strike change in tectonic style: San Andreas Fault zone, San Francisco Peninsula, Journal of Geophysical Research, 104:B5, 10719–10742, doi: 10.1029/1998JB900059.