ON THE INITIATION OF UNIDIRECTIONAL SLIP

A 2‐D model of a fault plane with inhomgeneous slip resistance is investigated using a finite element method. Slip is nucleated at a weak spot, and propagates initially in both directions. At one side of the nucleation point, the resistance to slip is assumed to increase along the fault. This causes the slipping edge to reverse its direction. In this way unidirectional slip with one leading and one trailing edge emerges. At the leading edge slip is assumed to propagate according to a critical shear stress criterion combined with a slip weakening law. At the trailing edge, where the process of healing occurs, slip is assumed to be arrested in an energy‐neutral way. The simulations indicate that a steady state unidirectional slip is approached. The edge velocities can be very high and even overshoot the shear wave velocity. Copyright © 1990, Wiley Blackwell. All rights reserved