During the last four years, the InSight mission has recorded more than 1,300 seismic events on Mars. The first surprising observation was the detection of a localized seismic activity along one of the youngest structures around the landing site: Cerberus Fossae. We jointly present results of a tectonic analysis of this giant fracture network of ~1200 km long, and the inversion of seismic moment tensors for nine marsquakes situated in Elysium Planitia. The refined cartography derived from high-resolution images (HiRISE, CTX) and Digital Elevation Models, enables us to describe a wide range of morphologies associated with dike activity at depth. Width and throw of the fossae are linearly correlated, and decrease eastward, suggesting a long-term direction of propagation of the dike-induced graben system, possibly from Elysium Mons. Cerberus Fossae are laterally segmented into a similar number of segments and sub-segments at different scales, as observed along faults and fractures on Earth. This property allows us to highlight local and regional areas of higher stress concentrations along the fossae (i.e., inter-segment zones and fracture tips). In addition, the moment tensor analysis reveals that seismic events are mostly characterized by extensional slip motion with strikes and dips in good agreement with surface fracture traces. They originated at 15-36 km depth, suggesting a possible reactivation of crustal faults and fractures in the vicinity of the dike network below Cerberus Fossae. Altogether, our results confirm that the internal dynamics of Mars are still operating, and that other regions on Mars could also be active.