It has been demonstrated recently that local magnetic field enhancement can originate from roughness (e.g. steps at grain boundaries) . We are willing to investigate if the quench site detected in superconducting niobium cavities can be related to such morphological defects. We recently developed a replica technique which allows to reproduce the internal surface of cavities (non destructive testing). Modeling of local increase of the magnetic field has been done in accordance with the morphological characterization. In particular we could observed the displacement of the quench location, and the evolution of the former quench site before and after chemical etching.