Spatiotemporal Analysis Of Seismotectonic State Of Injection-Induced Seismicity Clusters In The Western Canada Sedimentary Basin

The observations of spatiotemporal distribution of seismicity in western Canada indicate that the occurrence of earthquakes is tied to the hydraulic fracturing operations and disposal of coproduced wastewater. In this study, we investigate the temporal changes in the frequency-magnitude distributions for multiple clusters of induced events in regions where the level of background seismicity is low. The induced events are clustered into six major groups using density-based spatial and soft clustering algorithms based on their epicenters. Each cluster is identified by different distributions of earthquake magnitudes and injection scenarios. The linear relationship between the number of induced earthquakes and cumulative injection volume enables us, on a regional scale, to quantitatively characterize the seismotectonic conditions of the clusters using the estimates of the seismogenic indices. The seismogenic index provides a means to estimate the occurrence probability of earthquakes with a given magnitude induced during injection. The calculated seismogenic indices agree very well with the expected seismic response to hydraulic fracturing and wastewater disposal and show a strong correlation with tectonically accumulated strain energy. Statistical models based on the seismogenic index can be employed to mitigate the potential risk of large magnitude induced events.