5:15 PM - 7:15 PM
[SSS10-P09] Analysis of Source Characteristics of Earthquakes Potentially Induced by Wastewater Injection in Peace River, Alberta, Canada
Keywords:wastewater injection, induced earthquake, stress drop, source characteristics
The Peace River in Alberta, Canada, is actively engaged in oil sands development. During bitumen extraction, a mixture of bitumen and water is produced, necessitating underground wastewater injection for disposal. Near these injection wells, seismic activity has been observed in swarms, and on November 30, 2022, the largest earthquake ever recorded in Alberta's history, Mw5.2 (ML5.6), occurred. This earthquake is considered highly likely to be induced (Schultz et al., 2023), and wastewater injection has continued since then, with seismic activity remaining high.
In this study, we analyze the seismic activity in the Peace River, estimate stress drop values, and investigate the relationship between injection volume and injection rate to examine differences and similarities between induced and natural earthquakes. After the November 30, 2022, earthquake, the University of Alberta installed ten seismic stations near active injection wells. This study uses seismic data recorded by these stations at a sampling rate of 250 Hz, covering 2,214 earthquakes with magnitudes ranging from -1.97 to 5.04, occurring between December 6, 2022, and April 13, 2023. However, due to operational constraints, there were two periods during which no seismic data were recorded.
Near the three active injection wells, there are a pre-existing fault and the fault responsible for the Mw5.2 earthquake, with many earthquakes occurring along these two faults, forming major seismic clusters (Sun et al., 2023). For analysis, we selected 16 events with magnitudes of 2.5 or greater and estimated their source parameters using the Empirical Green’s Function (eGF) method. Smaller events, typically about one magnitude unit lower, were used as eGFs. The eGF method is an effective technique for accurately extracting source parameters by assuming that a small earthquake occurs in the immediate vicinity of a larger event, thereby eliminating the effects of path propagation and instrument response to isolate the source characteristics. In this study, we applied a bandpass filter of 0.5–2.0 Hz to the waveforms, calculated their correlation, and selected the three events with the highest average correlation values as eGFs.
The analysis results showed that the estimated stress drop values ranged from approximately 1 to 10 MPa, which is comparable to those of tectonic earthquakes. This suggests that the earthquakes analyzed in this study were likely triggered by stress perturbations caused by the Mw5.2 earthquake. However, as wastewater injection has continued, the spatial expansion of seismicity has been observed. Additionally, seismic activity increased significantly after March 2022, when injection volumes sharply increased, suggesting that wastewater injection also contributes to ongoing seismic activity. In the future, we plan to analyze smaller earthquakes and data from other seismic networks recorded before December 6, 2022, to further investigate detailed source characteristics and examine the relationship between wastewater injection and induced seismicity in greater detail.
In this study, we analyze the seismic activity in the Peace River, estimate stress drop values, and investigate the relationship between injection volume and injection rate to examine differences and similarities between induced and natural earthquakes. After the November 30, 2022, earthquake, the University of Alberta installed ten seismic stations near active injection wells. This study uses seismic data recorded by these stations at a sampling rate of 250 Hz, covering 2,214 earthquakes with magnitudes ranging from -1.97 to 5.04, occurring between December 6, 2022, and April 13, 2023. However, due to operational constraints, there were two periods during which no seismic data were recorded.
Near the three active injection wells, there are a pre-existing fault and the fault responsible for the Mw5.2 earthquake, with many earthquakes occurring along these two faults, forming major seismic clusters (Sun et al., 2023). For analysis, we selected 16 events with magnitudes of 2.5 or greater and estimated their source parameters using the Empirical Green’s Function (eGF) method. Smaller events, typically about one magnitude unit lower, were used as eGFs. The eGF method is an effective technique for accurately extracting source parameters by assuming that a small earthquake occurs in the immediate vicinity of a larger event, thereby eliminating the effects of path propagation and instrument response to isolate the source characteristics. In this study, we applied a bandpass filter of 0.5–2.0 Hz to the waveforms, calculated their correlation, and selected the three events with the highest average correlation values as eGFs.
The analysis results showed that the estimated stress drop values ranged from approximately 1 to 10 MPa, which is comparable to those of tectonic earthquakes. This suggests that the earthquakes analyzed in this study were likely triggered by stress perturbations caused by the Mw5.2 earthquake. However, as wastewater injection has continued, the spatial expansion of seismicity has been observed. Additionally, seismic activity increased significantly after March 2022, when injection volumes sharply increased, suggesting that wastewater injection also contributes to ongoing seismic activity. In the future, we plan to analyze smaller earthquakes and data from other seismic networks recorded before December 6, 2022, to further investigate detailed source characteristics and examine the relationship between wastewater injection and induced seismicity in greater detail.