The geometry of an active fault onshore Taranaki Peninsula, New Zealand was evaluated from a 3D seismic reflection volume. The geologic history of Taranaki Basin explains the complex tectonic-related deformation in the subsurface. Interpretation of the studied 3D seismic volume shows clearly imaged normal faults dominating the shallow structure, faults at deep reflections are poorly imaged. Interpretation of the seismic data also reveals possible gas flow associated with permeable normal faults. Analysis of seismic attributes helps in detecting the gas presence along faults in the subsurface. Kinematic forward models were constructed in this study to predict the active fault geometry at depth where it may not be very visible. The models are based on concepts of extensional fault-bend folding and were constructed to resolve geometric ambiguities in the interpreted volume. The modeled major fault in this study has a flat-ramp-flat geometry which cuts through the basement at depth.