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A comprehensive earthquake catalogue for northeastern British Columbia and western Alberta, 2014–2016

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Abstract

To gain a better understanding of induced seismicity in northeast British Columbia and western Alberta, we conducted an intensive analysis of seismic data to locate earthquakes that occurred within the area of 52˚N–61˚N, 126˚W–115˚W for the years of 2014 through 2016. Continuous seismic waveforms from as many as 43 stations operated by various organizations in the region were used in this study. A total of 5478 events were identified and located; but only 4916 solutions were deemed acceptable by our quality criteria. The number of earthquakes in our final catalogue is approximately three times the base level of the Canadian National Seismograph Network catalogue. In this report, we describe in detail our location procedures and how each source parameter (origin time, epicenter, focal depth, and magnitude) is determined. The earthquake catalogue is summarized in a table, while the phase picking data for individual events are presented in an ASCII file as a supplement to this report. The total numbers of events in 2014, 2015, and 2016 are 1287, 1575, and 2057, respectively. The overall magnitude of completeness of our catalogue is ML 1.8, an improvement from the value of 2.3 for the CNSN catalogue.
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... Second, coupled matrix poroelastic effects during HF in a fractured rock cause stress changes. 34 and Visser et al. 8 . Not all these earthquakes are within the Montney Formation; the colored circles outside of the area of the Montney Formation are natural tectonic earthquakes. ...
... This fact is important in assessing fault/ fracture stability because, in overpressured regions where the difference between the minimum and maximum principal stresses is smaller, a fault in the optimum orientation is likely to slip more easily. Of the 15,609 induced earthquakes presented by Visser et al. 34 and Visser et al. 8 , only 13 are located in stress area 1, whereas more than 13,000 occurred in stress area 4, where the mean pore pressure gradient is 13.5 MPa/km. Around Grande Prairie, where the Montney Formation's pore pressure gradient is around 7 MPa/km, no significant and large seismicity (M ≥ 4) has been reported even though more than 680 HF wells (represented by black circles in Fig. 5) have been stimulated with around 9 × 10 6 m 3 cumulative fluid injection (geoLOGIC™ Systems) into both the Duvernay and Montney Formations. ...
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... For example, three M4.5+ HF earthquakes occurred since 2015 in the Western Canada Sedimentary Basin (WCSB) [4][5][6][7] , as well as the 2017 M W 4.7, 2018 M L 5.7, 2019 M L 4.9, and 2019 M L 5.3 earthquakes in the Sichuan Basin, China [8][9][10] . Studies suggest many M3+ events near HF wellbores are generated on seismogenic faults that are critically stressed, where injection facilitates rupture by shifting the stress state toward failure through pore pressure increase 11,12 or poroelastic stress transfer 10,13,14 . ...
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