British Columbia's (western Canada) induced earthquake focal mechanisms

Earthquakes caused by human activities have been documented in many regions worldwide. Since industrial activities could trigger earthquakes, the topic of induced earthquakes has embraced a great deal of scientific interest in recent years. There are indications to link the fluid injection/extraction to several damaging events (i.e., Mw > ۵) in different parts of the Earth. However, recognizing those events in naturally elevated seismic areas is challenging. Estimating the source parameters for induced earthquakes reveals essential properties of their nature and can improve the findings about the dynamics and tectonics of such events. In this study, we determined the parameters of the Eikonal model for eight more significant induced earthquakes in the Western Canada Sedimentary Basin (WCSB) using the KIWI tool. These events occurred from August ۲۰۱۴ to March ۲۰۱۹ with a moment magnitude range of ۳.۷ to ۴.۴ and relatively low depths associated with the energy activities like hydraulic fracturing (HF) operations in the area. We performed the Inversion process in three steps to determine the source parameters, including eight parameters related to the point source and five parameters of the extended source. We aim to evaluate the parameters for creating a robust and reliable inversion in both the frequency and time domains. Results show that the depths of chosen earthquakes are shallower than the depths of specific seismic events in the area. Results of the inversion process for the ۲۰۱۴/۰۸/۰۴, ۲۰۱۴/۰۸/۰۹, ۲۰۱۵/۰۶/۱۳, ۲۰۱۵/۰۸/۱۷, and ۲۰۱۸/۱۱/۳۰ events revealed a compressional focal mechanism on planes striking northwest-southeast. This solution is compatible with the orientation and mechanism of pre-existing faults in the Rocky Mountain fold-and-thrust belt. The ۲۰۱۴/۰۴/۰۳, ۲۰۱۶/۰۱/۱۲, and ۲۰۱۹/۰۳/۰۴ events revealed left-lateral strike-slip focal mechanisms, which are well-matched with the slip mechanism in central Alberta.

کلیدواژه ها:

Induced Earthquake ، Earthquake Focal Mechanisms ، Hydraulic Fracturing ، Inversion Process ، Eikonal model.