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The 2016 Mw5.1 Fareview, Oklahoma earthquakes: Evidence for long-range poroelastic triggering at >30 km from disposal wells

Thomas H. Goebel, Matthew Weingarten, Xiaowei Chen, Jackson Haffener, & Emily E. Brodsky

Published August 12, 2016, SCEC Contribution #6657, 2016 SCEC Annual Meeting Poster #202

Much of the surge in seismic activity in the central United States has been linked to injection induced pressure changes on pre-stressed faults. This type of pressure-induced seismicity requires a direct hydraulic connection between injection wells and faults, which is complicated when earthquakes are located several kilometers beneath the injection zone and 10s of kilometers away from the injection well.

Here, we employ numerical and analytical models to resolve triggering mechanisms within the greater Fairview region, Oklahoma. The study region shows strong evidence for injection-induced seismicity, including an obvious lack of seismicity before 2013, followed by a rapid increase in background rates between 2014 and 2016. Most of the injection activity was concentrated toward the northwest of the study region resulting in a relatively cohesive zone of high-pressure perturbations between 0.1 and 1 MPa. This zone has a diameter of 10 to 20 km and produced much seismicity most likely by direct pressure effects and fault assisted pressure migration to larger depth.

Outside of the high-pressure zone, we observed two remarkably detached, linear seismicity clusters at 30 to 60 km distance. Our semi-analytical models reveal that poro-elastically-induced Coulomb stress changes surpass pressure changes at these distances, providing a plausible triggering mechanism beyond direct pressure effects. Our results indicate that both pressure and poroelastic stress changes can play a significant role in triggering deep and distant earthquakes by fluid injection and should be considered for seismic hazard assessment beyond the targeted reservoir.

Goebel, T. H., Weingarten, M., Chen, X., Haffener, J., & Brodsky, E. E. (2016, 08). The 2016 Mw5.1 Fareview, Oklahoma earthquakes: Evidence for long-range poroelastic triggering at >30 km from disposal wells. Poster Presentation at 2016 SCEC Annual Meeting.

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