As underground hydrogen storage (UHS) is expected to play a key role in future renewable energy systems, understanding the potential geomechanical risks, such as induced seismicity, is essential. Therefore, this study aims to assess the probability of induced seismicity associated with the prospect of large-scale UHS plans. We commence by developing simulation models with increasing complexity, starting from the basic characteristics of the salt formation, salt cavern, and operational conditions, and progressing to the inclusion of structural features within the salt formation as well as in the overburden and sideburden. A 2D finite element simulator is used to incorporate deformation and simulate creep behaviour, which is subsequently coupled with a rate-and-state Coulomb threshold model to compute the seismicity rate from stress changes. The developed framework accounts for the geological and mechanical characteristics of the heterogeneities that influence local stress fields, allowing us to identify conditions that may increase seismic risk or enhance stability.