Maximum magnitude of Injection-Induced Earthquakes on a Fault Governed by Rate and State Friction

Kyungjae Im, & Jean-Philippe Avouac

Submitted September 8, 2024, SCEC Contribution #13712, 2024 SCEC Annual Meeting Poster #126

We use analytical and numerical investigations to understand how a fluid injection affects the evolution of rupture radius and maximum magnitude (Mmax) on a fault governed by rate and state friction. We distinguish the radii of the creep (Rc) and rupture (Rr) slip modes and derive an expression for the evolution of maximum magnitude. Our result indicates that, when the initial stress is near critical or the flowrate is sufficiently high, the moment M0 released by seismic slip evolves with Cf(Qt/wS)^3/2 (Q: flowrate, t: time, w: reservoir thickness, and S: reservoir storage coefficient), where Cf is a stress parameter that reflects fault criticality and Qt/wS is a scaled injection volume linked to the cumulative hydraulic energy. These findings are confirmed by numerical simulations conducted with varied initial states. The simulations show that Rr behaves as a rupture arrest radius and Rc as the minimum possible radius for a given injection volume. We also observe that a high flow rate leads to a high rate of seismic events, allowing us to identify the upper bound on maximum magnitude evolution. Conversely, a low flow rate allows for larger volume injection without seismic events, but sudden large events can occur without any precursory events. This research provides valuable insights into the fundamental relationship between the injection characteristics and the magnitude of induced earthquakes as a function of the reservoir stress and hydraulic properties.

Key Words
Induced earthquake

Citation
Im, K., & Avouac, J. (2024, 09). Maximum magnitude of Injection-Induced Earthquakes on a Fault Governed by Rate and State Friction. Poster Presentation at 2024 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)