Performance Evaluation of the Regional Seismograph Network in Northeast British Columbia, Canada, for Monitoring of Induced Seismicity

摘要

An important factor in mitigation of seismic hazard from induced seismicity is properly established seismic networks suitable for consistent identification of small-to-moderate events (magnitudes less than four). Here, we evaluate the performance of the newly established regional broadband seismic network in northeast British Columbia, Canada. The seismic network was designed for monitoring of induced seismicity due to oil and gas operations related to hydraulic fracturing and fluid injection in the region. We use regional and local earthquake catalogs for the period 1985-2015 to analyze magnitude of completeness and epicentral uncertainty. We also perform a theoretical assessment of minimum detectable magnitude across the study region based on analysis of ambient noise and simulated ground motions. From the frequency-magnitude distribution of the reported events in the regional earthquake catalog, the magnitude of completeness has decreased similar to 1 magnitude unit from similar to 3 in the periods 1985-2013 to similar to 2 in the period 2013-2015 as a result of the establishment of new stations. The minimum detectable magnitude in the region is 1.6-2.6 based on the signal-to-noise ratio (SNR) of 10 and higher at four or more stations. By comparing the regional and dense array catalogs, we determine that the error in epicentral location in well-constrained areas by seismic stations is below 3 km in both east-west and north-south directions. However, location uncertainties can be up to 10 km in the east-west direction in areas where the current regional network is sparse. The magnitude detection threshold in the Montney Play, where most of the current oil and gas activities are taking place, can be further reduced by up to 1 magnitude unit with the addition of four new stations.