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Read Full Article (file size: 3784293 bytes) Cited by
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,
VOL. 6,
Q01009,
doi:10.1029/2004GC000838,
2005
Structure and mechanics of the San Andreas–San Gregorio fault junction, San Francisco, California
Tom Parsons
U.S. Geological Survey, Menlo Park, California, 94025, USA
Terry R. Bruns
U.S. Geological Survey, Menlo Park, California, 94025, USA
Ray Sliter
U.S. Geological Survey, Menlo Park, California, 94025, USA
Abstract
The right-lateral San Gregorio and San Andreas faults meet west of the Golden Gate near San Francisco. Coincident seismic
reflection and refraction profiling across the San Gregorio and San Andreas faults south of their junction shows the crust
between them to have formed shallow extensional basins that are dissected by parallel strike-slip faults. We employ a regional
finite element model to investigate the long-term consequences of the fault geometry. Over the course of 2–3 m.y. of slip
on the San Andreas-San Gregorio fault system, elongated extensional basins are predicted to form between the two faults. An
additional consequence of the fault geometry is that the San Andreas fault is expected to have migrated eastward relative
to the San Gregorio fault. We thus propose a model of eastward stepping right-lateral fault formation to explain the observed
multiple fault strands and depositional basins. The current manifestation of this process might be the observed transfer of
slip from the San Andreas fault east to the Golden Gate fault.
Received 8
September
2004;
accepted 3
December
2004;
published 29
January
2005.
Keywords: faults;
finite element model;
San Andreas;
seismic reflection;
structure.
Index Terms: 8110 Tectonophysics: Continental tectonics: general (0905); 8150 Tectonophysics: Plate boundary: general (3040); 8164 Tectonophysics: Stresses: crust and lithosphere.
Read Full Article (file size: 3784293 bytes) Cited by
Citation: Parsons, T., T. R. Bruns, and R. Sliter
(2005),
Structure and mechanics of the San Andreas–San Gregorio fault junction, San Francisco, California,
Geochem. Geophys. Geosyst.,
6,
Q01009,
doi:10.1029/2004GC000838.
This paper is not subject to U.S. copyright. Published in 2005 by the
American Geophysical Union.
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