AbstractThis paper develops a 2D time domain boundary element method (BEM) to solve the transient SH‐wave scattering from an inclusion with a unilateral frictional interface. The incident SH‐wave is assumed strong enough to break friction so that localized slip takes place along the interface. The present problem is indeed a non‐linear boundary value problem since the mixed boundary conditions involve unknown intervals (the slip and stick zones). In order to determine the intervals, an iterative technique is developed. As an example, we consider the scattering of a circular cylinder embedded in an infinite solid. The numerical results of the interface traction and relative slip velocity are presented. Copyright © 2003 John Wiley & Sons, Ltd.