Subsurface faults inferred from reflection seismic, earthquakes, and sedimentological relationships: Implications for induced seismicity in Alberta, Canada

Given the recent induced seismic activity in Alberta, identification of subsurface faults and areas of structural complexity has become increasingly important in improving our understanding of the controls on induced seismic events. Using a 3D geological model supplemented with 2D and 3D reflection seismic data, several basement-bounded and basement-rooted faults, which extend upward and into the Devonian strata, are identified in areas coincident with increased seismic activity. The presence of faults in the study area was confirmed through a statistically significant correlation of high-quality seismic event data from historical and recent (1970-2016) induced earthquakes in Alberta to the edge of the Devonian-aged Swan Hills platform. Along with the identification of faults using reflection seismic and earthquake hypocenter data, a review of the role of preexisting structure on depositional patterns that has been previously used to infer deep structure in this area, is also presented in this study. Several pre-existing extensional and/or transtensional style faults in the deeper strata and shallow basement of the study area are consistent with structure influencing the sedimentation of the overlying stratigraphy. Therefore, a better understanding of genetic fault-reef associations and the relationship to overlying strata may aid in identification of fault locations, style, and orientation. Considering the advancement of proper avoidance strategies during the planning stages of unconventional resource development or storage, this paper demonstrates the use of geological knowledge and relationships to identify areas comprising faults that may be prone to reactivation.