In this contribution we present numerical simulations of the development of faults in extensional environments, in rifts with coupled extension and dyking as well as in scenarios with only dyking. The numerical model allows for the study of fault initiation and propagation with dynamic development of faults and couples fluid dynamics for the dyking-induced with tectonically-induced stresses. Results show that faults nucleate at a depth of around 250 m in hybrid extensional-shear mode under pure extension when the material has a Young's Modulus range between 5 and 20 GPa and as mode I cracks at shallow depth of around 100 to 80 m at a Young's Modulus of 40–80 GPa. Following nucleation, faults propagate into vertical fissures towards the Earth's surface and into shear fractures at depth resulting in listric geometries. Continued extension leads to a complex network of conjugate faults and to central collapse structures. Dyking into an extensional system produces at least two nucleation points for faults, one on top of the dyke and a second point between dyke and the Earth's surface. Both of these nuclei develop into curved faults but with opposite curvatures forming fissures or mode I fractures at the Earth's surface and at the top of the dyke. Further extension of these coupled dyke and extension systems leads to relatively localized collapse structures on top of dykes with rhomboid blocks that are subsiding. Thin and shallow dyking leads to more concentrated collapse structures. In cases where dykes are the only structures producing stresses faults on top of the dykes propagate upwards as mode II shear fractures and develop shallow branches when they become close to the Earth's surface. Overall the models indicate that the most common and concentrated collapse structures develop when dyking and extension are both taking place and that the collapse structures develop complex zones with opening fissures at the Earth's surface, rhomboid collapsing blocks and faults with both normal and reverse movement.