2022 MW5.0 Range Hill earthquake, Midland Bain; reactivation of Precambrian fault within Midland Basin

Jeongung Woo, & William L. Ellsworth

Submitted September 10, 2023, SCEC Contribution #13252, 2023 SCEC Annual Meeting Poster #027

Fluid injection and the resulting pore pressure changes during unconventional hydrocarbon development and production have caused an increased level of seismicity in many oil plays, including in the Midland Basin in west Texas. Precise determination of induced earthquake hypocenters aids in the evaluation of potential causes when thousands of vertical and horizontal wells operate at different depths across the Basin. In response to growing numbers of felt events in the Midland-Odessa metropolitan area, the Texas Railroad Commission created the Gardendale Seismic Response Area (SRA) with mandated limits on both deep and shallow wastewater disposal. The surge of earthquakes that culminated in the MW 5.0 earthquake at the border of the SRA at Range Hill in December 2022 raised concerns about the influence of wastewater disposal in unregulated areas. In light of this event, the Gardendale SRA was expanded to encompass the Range Hill event. To delve into the specifics of the Range Hill earthquake, we extended our existing earthquake catalog to cover 2022 near the Range Hill sequence. This catalog facilitated a comprehensive investigation into event locations, magnitudes, focal mechanisms, and the seismogenic fault associated with the Range Hill earthquake. Eight pre-shocks were identified prior to the mainshock in 2022. Utilizing waveform inversion techniques, faulting mechanisms for both the Range Hill earthquake and its aftershocks were determined to be on basement normal faults with focal depths ranging from 4 to 6 km. The precision hypocenters define east-striking fault planes dipping to the north that are optimally oriented in the tectonic stress field. Considering the proximity of the Range Hill earthquake sequences to deep injection wells that continued to operate near the epicenter, we hypothesized that the primary driver for the Range Hill event was pore pressure diffusion from deep injection wells. Ongoing investigations suggest that regulation on permitted daily injection volumes within the SRA holds the potential to mitigate seismic risks in the region.

Key Words
Induced earthquake

Woo, J., & Ellsworth, W. L. (2023, 09). 2022 MW5.0 Range Hill earthquake, Midland Bain; reactivation of Precambrian fault within Midland Basin. Poster Presentation at 2023 SCEC Annual Meeting.

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