We propose a new method to track a seismic horizon with a discontinuity due to a fault throw assumed to be quasi-vertical. Our approach requires the knowledge of the two points delimiting the horizon as well as the discontinuity location and jump. We deal with a non linear partial derivative equation relied on the estimated local dip. Its iterative resolution is based on a Poisson equation with incremental Dirichlet boundary conditions. By exploiting a coherence criterion, we finally present an efficient method even when the discontinuity location and jump are unknown.