Poroelastic stress triggering of the December 2013 Crooked Lake, Alberta, induced seismicity sequence

The Crooked Lake area in Central Alberta, Canada, became seismically active in December 2013 with a sequence of earthquakes M-w 2.0 and higher. The earthquakes are suspected to be induced by hydraulic fracturing in nearby horizontal wells due to their strong spatiotemporal correlation. To investigate the physical mechanism of the induced seismicity near Crooked Lake, we calculate stress and pore pressure perturbations resulting from high-rate multistage fluid injection in the framework of linear poroelasticity. The calculated perturbations are used for seismic risk analysis based on the Coulomb failure criterion. Results show that most seismicity is within a positive Coulomb stress change regime, indicating that failure is promoted by injection of fluid. By comparing Coulomb stress results for different parameter settings, we show that elastic response of the solid matrix, instead of fluid diffusion, is more likely the dominant factor for the induced earthquakes shortly after fluid injection.