Abstract. Subsurface reservoir fractures and deformation bands are capable of significantly affecting fluid flow and storage in a variety of ways. In terms of flow effects, we typically encounter an unchanged or increased permeability when considering flow parallel to a fracture, whereas we expect a noticeably reduced permeability when considering flow across (perpendicular to) a deformation band. For this paper, we refine our efforts and focus on the flow effects of deformation bands. In order to explore the uncertainty effects of deformation bands, an idealized stochastic model for multi-component flow is used. The main assumption is that the width of the band is a random (uncertain) variable that follows a certain statistical distribution from which a number of realizations can be generated. Monte Carlo simulations can then be performed to obtain expectations of the saturation solutions in relation to the nature of uncertainty. As analytical expressions for the expectations can be derived in both cases, we are able to compare them with the Monte Carlo results. Furthermore, numerical solutions from a related stochastic perturbation model can be compared with Monte Carlo.