CRUSTAL DEFORMATION ASSOCIATED WITH 2-DIMENSIONAL THRUST FAULTING

The effect of the source-depth and the dip of the fault on the surface displacement field due to a long thrust fault embedded in an elastic half-space is studied. It is found that, for small dip angles, the displacement field is highly asymmetric about the fault strike, the displacement of the footwall is very small, and the horizontal displacement of the hanging wall shows a wavy pattern. The vertical displacement of the hanging wall is an uplift near the fault. For small dip angles, this uplift is maximum at a point almost vertically above the upper edge of the fault. As we go away from the fault strike, the vertical displacement changes sign, i.e., it becomes subsidence. For small dip angles, this subsidence is maximum at a point roughly vertically above the lower edge of the fault. Steeper fault dips decrease the subsidence relative to the uplift. For a vertical dip-slip fault, the horizontal displacement is completely symmetric about the fault strike and the vertical displacement is completely antisymmetric. The variation of the coseismic and postseismic shear stresses and shear strains for a surface-breaking long thrust fault with depth is studied for a viscoelastic half-space. It is found that, while the coseismic and postseismic shear stresses are of opposite signs, the coseismic and postseismic shear strains are of the same sign.