Statistical Modeling and Characterization of Induced Seismicity within
the Western Canada Sedimentary Basin
Abstract
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 forecasting 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
inter-event space-time distance distributions of earthquakes were
studied using the nearest-neighbour distance (NND) method. Additionally,
the frequency-magnitude statistics and aftershock parameters of several
clusters were analyzed using the Gutenberg-Richter relation and the
epidemic type aftershock sequence 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.