The 2016 NASA InSight lander is the first planetary mission designed to study the deep interior of Mars. InSight's Seismic Experiment for Interior Structure (SEIS) package will quantify global and regional seismic activity and determine parameters like core properties, mantle composition, and Martian lithospheric thickness. An improved understanding of the location, magnitude, and frequency of potential seismic sources is essential for optimization of instrument design, sampling strategy, and interpretation of mission data. We focus on forecasting seismic activity for the Cerberus Fossae of the Elysium Planitia, chosen for their proximity to the proposed landing site and their recent formation and assuming these are active tectonic grabens. The minimum age we determine for the units around the Fossae, using Context Camera and High Resolution Imaging Science Experiment imagery for crater density surveying, is 10 Ma, placing them in the Late Amazonian. We are able to determine the rate of motion from measurements of observed throw, assuming that the faults remain active. Digital terrain models, made from stereo-image pairs from the High Resolution Stereo Camera (HRSC), are used to determine the maximum throw on four graben systems. Using these measured throws to estimate a length-averaged slip and assuming an inferred slip rate from surface age, we estimate an annual moment release of . From this we calculate an annual size-frequency distribution of events using the Gütenberg-Richter relationship. We estimate that between 1.5×100and 1.9×105events per year will have an amplitude greater than the peak band noise and so will be detectable at the InSight landing site.