Discrete Fault Network Modeling of Induced Seismicity

Kyungjae Im, & Jean-Philippe Avouac

Published September 10, 2023, SCEC Contribution #12889, 2023 SCEC Annual Meeting Poster #118

Numerical simulations of earthquake sequences in a discrete set of finite size faults governed by rate-and-state friction can successfully reproduce earthquake phenomenology (e.g., seismic and aseismic slip, the Gutenberg-Richter law, the Omori and the inverse-Omori laws; Im and Avouac, 2023). Such simulations allow, in addition, to account for realistic complex fault geometries. Here we use such a 3-D Discrete Fault Network (DFN) model to simulate injection-induced earthquakes. The simulator is successfully benchmarked against BP5-QD, which is a simulation of quasi-dynamic ruptures for a planar fault that was designed for benchmarking simulations of earthquake sequences (Jiang et al., 2022). We next simulate the response to a point injection taking into account poroelastic coupling and assuming an initial stress field with a depth gradient. We tested three fault geometries: (i) a planar fault with a wide range of initial stress, (ii) a random network of interacting discrete faults, and (iii) a fault network similar to the fault network that was activated during the 2011 Prague earthquake sequence in Oklahoma. The simulations produce realistic sequences consistent with (i) a power-law evolution of maximum magnitude with total injection volume and (ii) the Gutenberg-Richter frequency-magnitude distribution. The discrete fault simulations accommodate fault criticality resulting from the applied stress field and fault orientation. We use these simulations to show how the initial stress and injection rate influence the maximum magnitude at a given injection volume. The earthquake simulations can be tuned to fit actual observations, such as the sequence of cascading events observed in the Prague earthquake sequence, by adjusting the model parameters and initial conditions.

Citation
Im, K., & Avouac, J. (2023, 09). Discrete Fault Network Modeling of Induced Seismicity. Poster Presentation at 2023 SCEC Annual Meeting.

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