Modeling Fault Activation and Seismicity in Geologic Carbon Storage and Shale-gas Fracturing - Under what conditions could a felt seismic event be induced? Summary Coupled fluid flow and geomechanical modeling with explicit and physics based modeling of fault activation is employed to investigate under what conditions a felt seismic event could be induced during deep injection activities associated with Geologic Carbon Storage (GCS) or shale gas fracturing. The analysis shows that for the case representative of GCS, felt seismic events (e.g. In any case, the initial stress field as well as the rock properties, whether more ductile or brittle, are important conditions that will determine whether a felt seismic events could be induced. Introduction The potential for fault reactivation and induced seismicity are issues of concern related to both stimulation of shalegas reservoirs and geologic carbon storage (GCS) (National Research Council, 2012; Zoback and Gorelick, 2012; Rutqvist, 2012; Davies et al., 2013).