Seismic Swarm S20230407.1 Near Carney, Oklahoma

A seismic swarm designated S20230407.1 occurred 3 km east-southeast of Carney in Lincoln County, Oklahoma. The sequence began at 06:19 on 6 April 2023 and concluded at 22:23 on 8 April 2023, spanning 64 hours and 4 minutes. During this period, 36 earthquakes were recorded, with hypocentral depths consistently between 6 and 7 km.

The swarm featured a mainshock of magnitude 4.0 at 08:57 on 6 April, followed by a magnitude 3.2 event at 09:16 the same day and a magnitude 3.3 event at 13:36 on 7 April. Additional notable events included a magnitude 2.5 earthquake at 14:44 on 7 April and a magnitude 2.1 event at 09:08 on 6 April. The remaining events ranged from magnitude 0.6 to 1.9, illustrating a typical swarm pattern of clustered, moderate-to-small shocks without a single dominant mainshock-aftershock sequence.

Oklahoma lies within the stable continental interior of North America, where natural seismicity is low. The regional geology is characterized by Precambrian basement rocks overlain by Paleozoic sedimentary strata. The area near Carney sits near the Wilzetta Fault system and other minor structures associated with the Nemaha Uplift. Since 2009, central Oklahoma has experienced a marked increase in seismicity, largely linked to wastewater injection from oil and gas operations that elevates pore pressure on pre-existing faults.

Historical records maintained by SeismoSight indicate three prior swarms in the Carney vicinity since 2000: one event in 2013, one in 2020, and one in 2021. The 2023 swarm represents the fourth such episode, reinforcing the pattern of episodic clustered activity in this localized zone.

The shallow focal depths of 6–7 km place the events within the crystalline basement, consistent with induced seismicity observed elsewhere in Oklahoma. No surface rupture or significant damage was reported from this swarm, although the magnitude 4.0 event was felt locally.

References

SeismoSight internal swarm catalog S20230407.1
Oklahoma Geological Survey earthquake database
United States Geological Survey Earthquake Hazards Program