Statistical Modeling and Characterization of Induced Seismicity within the Western Canada Sedimentary Basin

In western Canada, there has been an increase in seismic activity linked to anthropogenic energy-related operations including conventional hydrocarbon production, wastewater fluid injection and more recently hydraulic fracturing (HF). Statistical modeling and characterization of the space, time and magnitude distributions of the seismicity clusters is vital for a better understanding of induced earthquake processes and development of predictive models. In this work, a statistical analysis of the seismicity in the Western Canada Sedimentary Basin was performed across past and present time periods by utilizing a compiled earthquake catalogue for Alberta and eastern British Columbia. Specifically, the frequency-magnitude statistics were analyzed using the Gutenberg-Richter (GR) relation. The clustering of seismicity was studied using the Nearest-Neighbour Distance (NND) method and the Epidemic Type Aftershock Sequence (ETAS) model. The obtained results suggest that recent regional changes in the NND distributions, namely a disproportionate increase in loosely and tightly clustered seismic activity over time, are unnatural and likely due to the rise in HF operations for the development of unconventional resources. It is concluded that both these loosely and tightly clustered earthquake subpopulations differ measurably from what may be the region’s tectonic seismic activity. Additionally, HF treatments have a greater probability of triggering swarm-like sequences that sharply spike the seismicity rate and are characterized by steeper frequency-magnitude distributions. Conventional production and wastewater disposal operations largely trigger loosely clustered activity with more typical magnitude-occurrence rates