Stress near geometrically complex strikeslip faults: Application to the San Andreas Fault at Cajon Pass, southern California
Abstract
Slip on an undulatory strikeslip fault induces predictable residual stresses in the adjacent crust. Elastic analytic and finite element models are developed to quantify these stresses for arbitrary fault geometries. Across faultparallel planes, domains of reverse, normal, rightlateral and leftlateral residual stresses are induced near the bends in the fault. These residual stresses increase in magnitude from one slip event to the next, typically reaching failure level after several events. A twodimensional analytic elastic plate model for slip on a sinusoidal fault provides general results on the scales and patterns of slipinduced stresses, and Fourier synthesis allows for the solution with arbitrary but small fault distortions. Maximum faultnormal residual stress is proportional to the square of the wavenumber of the sinusoidal trace and decays exponentially away from the fault, reduced to 2/e times the maximum value at a distance equal to 1/wavenumber. This faultparallel residual shear stress oscillates between dextral and sinistral along the fault, with maximum magnitude adjacent to the maximum excursions in the fault trace. Faultparallel residual shear stress is maximum at a distance from the fault of 1/wavenumber, where its magnitude is 1/e times the maximum normal stress on the fault. Two and threedimensional finite element analyses extend the analytic model; they account for depthdecaying fault perturbation amplitude and slip deficit and are valid for large fault undulations. Application of the model to the San Andreas fault in the Cajon Pass region produces the complex distribution of faultparallel normal, reverse, rightlateral and leftlateral structures recognized near the main trace. Leftlateral stresses on planes subparallel to the San Andreas fault at the Cajon Pass well are predicted by this model.
 Publication:

Journal of Geophysical Research
 Pub Date:
 April 1992
 DOI:
 10.1029/91JB02644
 Bibcode:
 1992JGR....97.5081S
 Keywords:

 Finite Element Method;
 Plates (Tectonics);
 San Andreas Fault;
 Stress Distribution;
 Geodynamics;
 Mathematical Models;
 Shear Stress;
 Geophysics;
 Tectonophysics: General or miscellaneous