Fig. 2: Numerical models setup.
a Map view: domain geometry and boundary conditions. The red dashed line indicates the imposed shear direction. The green arrows indicate the imposed velocity, while the blue arrows exemplify the two end-member velocity fields resulting from the application of Navier-Slip condition when the strain rate is distributed (left) or localized (right) in the solution of the Stokes equation. b Vertical cross-section showing the initial rheological stratification. The initial geotherm is in red. The initial yield stress envelope is in black. The grey curve shows the yield stress for the fully softened material at initial conditions. c Map view: initial plastic strain distribution. The red dashed lines indicate the shear direction passing by the centers of the two Gaussian functions. α is the angle between the shear direction and the weak zones, and Δ is the distance taken perpendicularly to the shear direction between the two weak zones.
