Slip Characteristics of Induced Earthquakes: Insights from the 2015 Mw 4.0 Guthrie, Oklahoma Earthquake

Colin N. Pennington, Takahiko Uchide, & Xiaowei Chen

Published April 16, 2022, SCEC Contribution #11846

To better quantify how injection, prior seismicity, and fault properties control rupture growth
and propagation of induced earthquakes, we perform a finite-fault slip inversion on a Mw 4.0 earthquake that
occurred in April 2015, the largest earthquake in an induced sequence near Guthrie, Oklahoma. The slip
inversion reveals a rupture with slip patches that are anti-correlated to the locations of prior seismicity. The
prior seismicity driven by low pore pressure changes and static stress changes occurred on weaker portions
of the fault, while the Mw 4.0 earthquake likely ruptured relatively stronger portions of the fault. To resolve
if pore pressure changes or the initial underlying stress distribution and fault strength controlled the final
slip distribution of the Guthrie Mw 4.0 earthquake, we compare strike-slip events of similar magnitude from
tectonically active regions and previously inactive regions. Earthquakes on reactivated faults exhibit different
slip distributions than active regions, they have more prominent and well separated slip patches, a behavior
often associated with faults of lower fault maturity. Pore pressure shows little effect on the distributions. These
observations suggest that the initial underlying stress distribution and fault strength of reactivated faults in low
deformation regions is the primary controlling factor of the slip distribution with pore pressure perturbations
and earthquake interactions being secondary. Therefore, Guthrie Mw 4.0 earthquakes slip distribution was
enhanced by pore-pressure perturbations and earthquake interactions by creating an optimal stress state for its
failure, but the slip distribution itself is controlled by its fault's initial stress and strength state.

Citation
Pennington, C. N., Uchide, T., & Chen, X. (2022). Slip Characteristics of Induced Earthquakes: Insights from the 2015 Mw 4.0 Guthrie, Oklahoma Earthquake. Journal of Geophysical Research: Solid Earth,. doi: 10.1029/2021JB023564.