Within its mission to design and build an engineered storage facility for thehigh level radioactive wastes in the eastern Paris Basin, the French National Radioactive Waste Management Agency (Andra) is conducting innovative and extensive characterization of the Callovo-Oxfordian claystone formation (Cox) and surrounding Middle and Upper Jurassic shallow-marine carbonate formations. High resolution 3D seismic data are used to model the distribution of mechanical and hydrogeological properties, of the geological formations (1). Assessing the reliability of the modelling is crucial for making decision on the design of the radioactive waste facility. We show how first assessing the reliability of seismic stacked amplitudes that are input to the geophysical inversion is the cornerstone of the whole model reliability assessment process. Stochastic processing of the pre-stack amplitude gathers enables to compute Stochastic Quality Indexes (SQI) attached to stacked amplitude data. The computation and distribution of SQI results and its contribution to the mechanical and hydrogeological model is discussed.