State of stress near the San Andreas fault: implications for wrench tectonics

Journal Article · Tue Dec 01 00:00:00 EST 1987 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1987)15<1143:SOSNTS>2.0.CO;2· OSTI ID:5340328

Mount, V S; Suppe, J

Borehole elongations or breakouts in central California show that the direction of regional maximum horizontal stress is nearly perpendicular to the San Andreas fault and to the axes of young thrust-related anticlines. This observation resolves much of the controversy over shear-stress magnitude in the crust and around the San Andreas fault specifically. A low shear stress of 10-20 MPa (100-200 bar) or less on the San Andreas fault, suggested by heat-flow and seismic observations, is compatible with a high regional deviatoric stress (100 MPa, 1 kbar) when the observed principal stress directions are considered. Therefore, the San Andreas fault is a nearly frictionless interface, which causes the transpressive plate motion to be decoupled into a low-stress strike-slip component and a high-stress compressive component. These observations suggest that standard concepts of transpressive wrench tectonics - which envisage drag on a high-friction fault - are wrong. The thrust structures are largely decoupled from the strike-slip fault.

• Research Organization: Princeton Univ., NJ (USA)
• OSTI ID: 5340328
• Journal Information: Geology; (United States), Vol. 15:12
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CALIFORNIA
GEOLOGIC FAULTS
STRESS ANALYSIS
CONTINENTAL CRUST
FRICTION FACTOR
HEAT FLOW
SEISMIC SURVEYS
SHEAR
STRESSES
TECTONICS
EARTH CRUST
FEDERAL REGION IX
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
NORTH AMERICA
SURVEYS
USA
580201* - Geophysics- Seismology &amp; Tectonics- (1980-1989)