Deciphering the Stress State of Seismogenic Faults in Oklahoma and Southern Kansas Based on an Improved Stress Map

Abstract

Fault location and geometry are critical considerations in the reactivation of preexisting faults. Here, we combine relocated earthquake catalogs and focal mechanisms to delineate seismogenic faults in Oklahoma and southern Kansas and analyze their stress state. We first identify and map seismogenic faults based on earthquake clustering. We then obtain an improved stress map using 2,047 high‐quality focal mechanisms. The regional stress map shows a gradual transition from oblique normal faulting in western Oklahoma to strike‐slip faulting in central and eastern Oklahoma. Stress amplitude ratio shows a strong correlation with pore pressure from hydrogeologic models, suggesting that pore pressure exhibits a measurable influence on stress patterns. Finally, we assess fault stress state via 3‐D Mohr circles; a parameter understress is used to quantify the level of fault criticality (with 0 meaning critically stressed faults and 1 meaning faults with no applied shear stress). Our results indicate that most active faults have near vertical planes (planarity >0.8 and dip >70°), and there is a strong correlation between fault length and maximum magnitude on each fault. The fault trends show prominent conjugate sets that strike [55–75°] and [105–125°]. A comparison with mapped sedimentary faults and basement fractures reveals common tectonic control. Based on 3‐D Mohr circles, we find that 78% of the faults are critically stressed (understress ≤0.2), while several seismogenic faults are misoriented with high understress (>0.4). Fault geometry and local stress fields may be used to evaluate potential seismic hazard, as the largest earthquakes tend to occur on long, critically stressed faults.

Correlation Between Poroelastic Stress Perturbation and Multidisposal Wells Induced Earthquake Sequence in Cushing, Oklahoma

“…Zoback and Townend (2001) suggested that intraplate crust is in a state of failure equilibrium based on worldwide borehole observations. Based on a high-resolution stress map for Oklahoma (Qin et al, 2019), the orientation of the Cushing fault that hosted the M5 earthquake is optimally oriented for failure ( Figure 1).…”

Basement‐controlled deformation of sedimentary sequences, Anadarko Shelf, Oklahoma

“…Furthermore, the structural inheritance of basement fault systems by the sedimentary sequences may explain the recent widespread seismogenic strike‐slip reactivation in north‐central Oklahoma, attributed to sedimentary‐to‐basement migration of fluids (e.g. Kolawole, Johnston, et al, 2019; Qin, Chen, Carpenter, & Kolawole, 2018; Qin et al, 2019).…”

Basement-Controlled Deformation of Sedimentary Sequences, Anadarko Shelf, Oklahoma

“…First, the area hosts the occurrence of sporadic and widespread wastewater injection-induced seismicity (e.g., Kolawole et al, 2019b). The Arbuckle Group is the primary zone of wastewater disposal, and the Precambrian Basement hosts most of the resulting induced seismicity (e.g., Kolawole et al, 2019). Second, the shelf area hosts the STACK ("Sooner Trend, Anadarko, Canadian and Kingfisher") and Mississippi Lime Plays, which are currently some of the most active unconventional hydrocarbon exploration plays in North America (e.g., Yee et al, 2017).…”

“…However, we do not rule out the possibility. Both sub-horizontal (sill) and sub-vertical (dike) mafic sheet intrusions occur in the outcrop exposures of the Oklahoma basement, where the sills commonly branch out from the dikes (e.g., Lidiak et al, 2014;Kolawole et al, 2019). However, the absence of dike-related reflections in our seismic dataset may be explained by the inherent difficulty of seismic reflection imaging of dikes (e.g., Zaleski et al, 1997;Wall et al, 2010;Phillips et al, 2018).…”

“…In other basins where basement-rooted transpressional faults exist, near-fault diagenetic hydrothermal alterations can localize "light-bulb" structures and influence the local petroleum system and metallic-ore mineralization trends (e.g., the Appalachian foreland basins of Eastern US, Evenick, 2006;Evenick & Hatcher, 2006;Smith Jr & Davies, 2006). Further, the structural inheritance of basement fault systems by the sedimentary sequences may explain the recent widespread seismogenic strike-slip reactivation in north-central Oklahoma, attributed to sedimentary-to-basement migration of fluids (e.g., Qin et al, 2018Qin et al, , 2019Kolawole et al, 2019b).…”