ABSTRACT

We produce year‐by‐year probabilistic seismic hazard maps based on the seismicity from 2011 to 2018 for the western Canada sedimentary basin (WCSB) and compare them with corresponding maps of the baseline historical hazard levels through 2010. Rates of earthquakes across the WCSB, of moment magnitude (M)3.0, have increased in the past decade because of oil and gas development activities, especially hydraulic fracturing in long horizontal wellbores. The increased activity rates have elevated the hazard on a short‐term basis, dramatically in some locations. For example, in the area west of Rocky Mountain House, the 1/2500 per annum ground motions (peak acceleration and high‐frequency response spectra) are greater than those in the 2015 national seismic hazard model by more than a factor of 4; the 2015 hazard model was based on seismicity to 2012 and attempted to exclude induced earthquakes.

The intent of this study is to provide 1 yr hindcasts of the impact of induced seismicity on regional hazard. Such retrospective forecasts show how the observed seismicity in each specific year would translate into a seismic hazard map. This is a useful first step in developing earthquake hazard forecasts for the WCSB, which might eventually forecast future hazard based on the relationship between operational and geological factors and seismicity response.

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