Improved Local Magnitude Estimation of Induced Earthquakes in the Kiskatinaw Seismic Monitoring and Mitigation Area, British Columbia, Canada

Abstract The Kiskatinaw Seismic Monitoring and Mitigation Area (KSMMA) in northeastern British Columbia, Canada, has experienced increasing induced seismicity from hydraulic fracturing and fluid injection, prompting regulatory measures requiring the suspension of industrial operations for earthquakes of local magnitude (ML) 3.0 or greater. Accurate magnitude estimation is therefore critical, yet a widely used regional ML scale may misestimate shallow, near-source events typical of KSMMA. To address this limitation, we developed a KSMMA-calibrated ML scale using continuous seismic records during 2020 from 15 stations of the Earth-System Observing Network–Réseau d’Observation du Système terrestrE (EON-ROSE) dense array and eight stations of the Geological Survey of Canada (GSC)–British Columbia Oil and Gas Commission (BCOGC; now BC Energy Regulator, BCER) Induced Seismicity Study network. Event information from an existing catalog was used to supplement the dataset, but waveforms were reprocessed and Wood–Anderson amplitudes were remeasured uniformly. Earthquakes were detected using the phase-picking, association, location, and matched-filter (PALM) algorithm, which combines the ratio of short-term to long-term average, kurtosis, association, and matched-filter methods. Hypocenters were located with both absolute (HYPOINVERSE-2000) and relative (hypoDD) methods. The ML was developed following Richter’s definition, with distance corrections referenced to 17 km. Station corrections and attenuation coefficients were derived through generalized linear inversion. Amplitudes were measured on vertical-component Wood–Anderson simulated seismograms using a 1 Hz high-pass filter. The final dataset consisted of 4043 earthquakes, with ML values ranging from −0.53 to 3.04. Compared with previously used scales, the new calibration systematically yielded magnitudes approximately 0.3 units lower on average. Application of a KSMMA-specific ML scale, together with station corrections, yielded more consistent network-wide ML estimates and reduced scatter in event–station magnitude residuals. This regionally tailored ML scale improves characterization of induced seismicity in the KSMMA and supports more reliable seismic hazard assessment and risk management.