The behavior of seismic faults depends on response of the microconstituents trapped in the region between plates, which is usually termed gouge. The gouge is a discrete particle region composed of amorphous grains subject to high confinement pressure. Conversely, the regions surrounding the gouge can be conceptualized as two continuum domains. The study of such system requires the understanding of several scales, from micro meters (particle size) to meters and above to properly account for loading conditions. Simulating this system numerically remains a challenge, as, in order to capture proper physics, both the continuum and discrete aspects of the system must be harmoniously incorporated and coupled into the model. An energy-based coupling strategy between Finite Element Method, used to resolve the continuum portions, and Discrete Element Method, to model the granularity of the interface, is introduced. Two different coupling strategies are considered: "strong" and "weak" coupling. The strong coupling is a generalization to granular material of the Bridging Method [1] used for continuum domain and regular lattice. The limitations of such coupling when it comes to connect continuum to amorphous (not-ordered) discrete media are highlighted. The Weak coupling is then introduced to overcome these limitations. As a practical example, we consider a secondary fault and analyze the passing through of pressure/shear waves (assumed to have been generated elsewhere) and analyze the new wave field that emanates from the fault as a consequence of grain rearrangement in the fault.