Axen, G.J., Luther, A. and Selverstone, J. Paleostress directions near two low-angle normal faults PDF Print E-mail
Axen, G.J., Luther, A. and Selverstone, J. recently published Paleostress directions near two low-angle normal faults: testing mechanical models of weak faults and off-fault damage in the Geosphere Journal. "This paper uses paleostress inversions derived from minor shear fractures in the upper 30 m of the footwalls (fault core, fractured damage zone, and background sites) of two low-angle normal faults in southern California to test several published models of slip on "weak" faults and of damage accumulation along faults. We conclude that the maximum principal stress was oriented at high angles to both faults during slip, precluding models in which the maximum principal stress becomes rotated to to low to moderate angles to the faults due to elevated pore-fluid pressure or increased damage near the faults, and that near-fault damage did not occur due to stress fields controlled by slip gradients near the fault tip lines either during initial fault propagation or subsequent earthquake rupture propagation. Models are allowed in which slip in the seismogenic crust is aided by moderately elevated pore-fluid pressure and non-negligible tensile strength of the rocks around the faults, and in which the maximum principal stress plunges moderately in the brittle-plastic transition."
Created: ( Thursday, 05 November 2015 13:25 )
Last Updated: ( Thursday, 05 November 2015 13:26 )
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