Connecting fluid-flow along faults to hydraulic fracturing induced seismicity: an integrated geoscience study

A swarm of moderate-magnitude earthquakes was induced by hydraulic fracturing (HF) in 2011, near Cardston, Alberta. Though the cause of the earthquakes was not in question, the mechanism(s) linking the HF to the earthquakes was not clear. This geoscience study combines insights from earthquake seismology, seismic geophysics, and geology to identify the factors that contributed to the seismicity observed in this case. We demonstrate that conduits of paleo-fluid-flow communicated HF pressure a great distance, triggering movement along a basement-rooted fault ~1.5 km below the Stettler—Big Valley Reservoir zone. The revelation that paleo-hydrology can influence present-day susceptibility to HF-induced seismicity suggests another geological factor that should be utilized to avoid earthquake hazards.